Category: Environment

Post 2060: My life with a two-headed three-ton ductless mini-split.

 

I’m now the owner of a two-headed three-ton ductless mini-split.

And lovin’ it.

 

Pictured above:  Those boxes, on the wall, are the inside portion of my new ductless mini-split heat pump.

They blow hot air.  They blow cold air.  When you ask them to.  One per room is adequate, unless you dwell in a house of unusual size.  And one per room is required, if you want heat (and AC) in that room.

The outside, it’s about as attractive as you would expect, for a heat pump.  Slightly uglier than a standard system, owing to the need to run refrigerant and electrical lines up the outside of the house, to each of those interior boxes, connecting to the compressor unit at ground level.  Here, the line covers (the things that look like aluminum downspouts) blend right in with the electrical, phone, FIOS and whatnot already hanging off the vinyl siding at that end of the house.

For me, they were less expensive than my closest alternative. I paid $13K installed, $11K after the Federal tax credit.  If I’d replaced my dead ground-source heat pump, it would have been $25K, $17.5K net of (a much higher) tax credit.  I picked the contractor based on reputation, on a friend’s recommendation, and on the fact that we were immediately on the same wavelength, regarding a nice, simple installation.

Mine is a three-ton (36000 BTUH) compressor, hooked up to two 1.5 ton heads.  Took a day and a half to install, but the HVAC guy was training a couple of guys, so a one-day install would not have been out of the question if I’d been in a hurry.

These Mitsubishi units will produce heat down to 5F.  Below that, I think they automatically shut off.  At 5F, their heating efficiency will have fallen to the point that they were merely twice as efficient as an electric space heater (COP 2.1), instead of 3.5 times as efficient (COP 3.5) at 47F.

The same company (Mitsubishi) that makes these makes a “hyper heat” compressor that will run at outside temperatures down to -13F, but the outside pieces (the compressors) for those run about twice the cost of a standard compressor, near as I can tell.

We got a standard unit that’ll only function down to 5 degrees F.  But, thanks to global warming, that should do us, as this decade’s USDA hardiness zone maps bumped us from Zone 7A to 7B, meaning that 5 F is not a bad guess for the lowest temperature we’ll ever see here, ever again.  And if not, the old gas-fired hot water baseboards still work.

On paper, they’re as efficient as any other option I could get, including ground-source heat pumps.  I did an entire post on that earlier (Post #2032).  Once I got up an apples-to-apples comparison, the near-equality was obvious.

For typical winter temperatures around here, these ought to run at around COP 3.5, or, as noted, three-point-five times as efficient as an electric space heater.  In practice, they look like they’re going to do even better than I thought, owing at least to their “inverter” continous-speed technology.

I get the distinct impression that these heat pumps, with their variable-speed compressors and blowers, like being operated for long periods of time, at a relatively low load.  So I’m rethinking my life-long habit of nighttime temperature setbacks to save energy.  Don’t now what the outcome of that analysis will be.

The only thing you really need to install one is a place to put the compressor (near where the inside heads are), and some way to run a 220V electrical line there.  The electrical power for the interior heads is routed through the outside compressor unit.  So the electrical lines for the interior heads run right alongside the refrigerant lines.

And you need to have an empty 220V breaker in your electrical panel, of about the right size.  This three-ton unit needed a 25-amp breaker.  The installer just pulled the wires out of the breaker for the now-useless ground source unit, and put in the wires powering the new one.  The legally-required outside electrical cutoff comes with surge suppressor built in.

The refrigerant is R410A, which seems to be the only option for any HVAC equipment that I could buy.  It has greatly reduced ozone-depletion potential relative to old-school Freon (R22), but it’s still a potent greenhouse gas.  Less than ideal, but that’s what commodity heat pumps are using.

Some background follows.

 

Ductless mini-split.  A product clearly named by its competitors.

It’s just a normal heat pump.

The best way to describe it is by contrasting it with “normal” central heating/AC.  For a single-family home, the typical central heat/central AC set up is:

  • one hot/cold coil in the house
  • sitting inside a blower housing
  • typically in your basement or attic,
  • blowing conditioned air into your ducts, and from there to all the rooms of your house.

A mini-split is decentralized heating and AC, as far as the inside of the house is concerned.

  • one hot/cold coil in each room,
  • sitting in its own stand-alone blower cabinet,
  • blowing conditioned air directly into the room,
  • and so cooling or heating that one room.

Outside, by contrast, a typical mini-split system is more-or-less the same as central heating systems.  For reduced installation cost (and, I’d bet, better operating efficiency), you run multiple mini-split “heads” off one outdoor compressor unit.  This then requires you to run multiple sets of refrigerant lines to that one compressor, as opposed to the one set that would run to the compressor in central (ducted) forced-air system.

You pick the combination of outside compressor and inside head(s) to give you what you want.  My outside three-ton unit can take from two to four heads, as long as the total “ton” capacity of those heads is three tons of cooling (36000 BTUH).  Available compressors and heads both span a range of tonnages.

Nothing about the name “ductless mini-split” is even the tiniest bit helpful in understanding what it is.

First, it’s not mini.  It’s a full-sized HVAC unit, in terms of heat and cooling capacity.  Ours is a “three-ton” unit, meaning 36,000 BTUs/hour cooling capacity.  This is roughly the same as the heat pump it replaced.  In this climate, that’s enough for a small house, or, in our case, the first floor of a larger house.

The only “mini” part is that these units have compact, quiet outdoor part.  Two strong men can lift and carry one, and just bolt it down in place, as a unit.  So they are mini, in that the outdoor (compressor) piece of this isn’t a big louvered metal box that makes a hellacious racket when the AC or heat pump comes on.  Which is the tradition in the American ‘burbs.

Second, split just means “normal”.  As in, there’s an inside part, and an outside part, and some refrigerant lines and wires connecting the two parts.  Just like every suburban home central AC that you’ve ever seen.

Arguably, the only AC system you’ve ever seen that isn’t a “split” unit is a window air conditioner.  There, the outdoor and indoor components are in the same metal box.  But any home central AC you’ve ever seen is a split unit.

(And I now know why “split” is even a thing, for HVAC contractors.  For ground source heat pumps, you actually do have an alternative to split units, called “package” units, where the heat pump and the air handler (that blows the heated or cooled air into your duct work) are combined in a single box.  These units get a generally higher efficiency rating than split units, but I never did decide how real that was.  It almost seemed as if that might be a side-effect of the way these were tested.  Anyway, split versus packaged matters for ground-source heat pump options, but pretty much for nothing else having to do with home HVAC.)

Third “ductless” just means that the part that blows air around your house is a self-contained blower unit.  Typically, the “head” resides in a plastic cabinet, mounted high on a wall, as above.  But you can get them as console-type units.  Or as units that recess into the ceiling.  (And there are, in fact, ducted versions of these, where they are set up to be connected to a set of duct.  But that’s not their selling point.)

Not pushing air through ducts gives these a modest energy advantage, all other things equal.

But a downside of “ductless” is that there’s no air return in this system, as there is an a traditional central forced-air system.  Air does not flow out of the ducts, toward the return.  It just flows out into the room its in.  That limits these to heating essentially one open space per head.  OTOH, these units seem to have no problem throwing warm air for a considerable distance.

It’s a different heating and cooling gestalt

In the typical central forced-air heat or AC system, you blow air out the ducts, and suck it back up in some distant central air return.  This means that air flows through all the rooms, and you can count on that air flow both to mix the air, and to make the conditioned air travel the full distance from duct outlet to return inlet.  Ideally, the result is a uniformly heated or cooled living space, and no apparent breezes.

A ductless mini-split is a different beast entirely, and no nearly so elegant as central forced air.

There’s no air return.  This limits the “throw” of each unit to the space in which it can manage to blow its warm or cold air.  The result is that a) you definitely get a warm breeze if it’s really cranking, and b) the air temperature in the room is not as uniform as it is with central forced-air systems.

Neither of which bothers me in the least. I actually like both aspects.  And mine are strong enough to heat the living-dining room from one end to the other, which has to be 30-some feet.

The upshot is that if you want nice, uniform, breezeless heat throughout a room, these are not for you.  As far as the user is concerned, these are more like having the best space heater you’ve ever used, hanging on the wall of your house.  It works well, but not as nicely as a properly-configured central forced-air system.

(N.B., a 1.5 ton head is 18,000 BTUH, which equates to the heat you’d get from about a 5000-watt resistance space heater, where the biggest plug-in 120V space heater you can buy is 1500 watts.  The astute reader will recognize that 5000 watts at 120V would be … way more electricity than the entire compressor uses, if it sits on a 25-amp breaker.  Which is neither a violation of the laws of physics nor magic, but the whole point of using a heat pump, because the coefficient-of-performance (COP) is bigger than 1.0.  You do, in fact, get more heat out of it, than is embodied in the energy it takes to run it.  Because it’s not a heater, it’s a heat pump.)

 

The back story

In 2004, the previous owner of my house had a ground-source heat pump system installed.  Mile of pipe buried in the back yard, hooked up to two heat pumps, retrofit to the existing duct work, using the existing hot-water gas-fired baseboards as secondary heat for the heat pumps.

(Secondary heat is the additional heat source the system turns on if it looks like it’s taking too long for the heat pumps alone to bring the house up to temperature, or maintain temperature.)

In 2007 we bought the house thinking, neat, that’s the most efficient heating we can get.  Only after we lived with it for a while did we fully appreciate what a botched Frankenstein’s monster our heating system was.

This 1959 home was an energy use nightmare.  (Ah, bad dream, maybe.)  Rather than insulating the attic and ceiling spaces, or dealing with the huge air leaks, or the (believe-it-or-not) uninsulated walls, or the four big open fireplace chimneys, … the previous owner figured he’d just install his high-tech redneck heating system and be done with it.  And botched that install in several important ways, to boot.

For example, I ask you, what sane home buyer looks at a nice new high-end kitchen remodel, stone countertops, cherry cabinets, stainless high-end appliances and says, that’s a very nice kitchen, but, does that come with heating and cooling?

Because in my case, the answer was no.  They tore out the old hot-water baseboard heat and, to a very close approximation, replaced it with nothing.  Which, as the owner, you don’t really figure out until winter sets in, some time later.

What sort of person would do that, in their own kitchen remodel?  The same sort of person that did all the rest of the HVAC system.  Near as I can tell, absolutely no aspect of it was planned or executed well.  Let me omit the rest of the kvetching by saying that it has never worked well.  And the kitchen is always ass-freezing cold in the winter.  And that, upon closer inspection, that last problem seemed un-fixable.

So we let Frankenstein be.  And did a lot of baked goods in the winter.  Slow-cooker recipes.  And so forth.

FF to 2024.  The ground-source heat pump for the first floor is dead,and the one for the second floor is failing.  And I wasn’t shedding tear over its demise, given the miserable performance.

Until, that is, I found out it was going to cost me $50K to replace them.

But there’s nothing like a pending major expenditure to sharpen your focus, if not your wits.  For various reasons, my wife and I decided that it was stupid to spend $50K to repeat the previous owner’s mistakes with fresh equipment.  And that maybe, just maybe, for the first time since we moved in, we could actually have a warm kitchen.

Our solution was to ignore the dead ground-source heat pump, ignore the grossly under-sized duct work, the cobbled-up secondary heat, the @#@#$ wireless thermostat that worked sometimes.  Rather than try to work around the same problems that the last guy was unable to fix, we decided to start fresh with an air-source ductless mini-split that had nothing whatsoever to do with the existing Frankenstein of a system.

And that’s how we ended up here.

Post #2036: Replacing my heat pumps III: The tax angles.

 

Winter approaches. 

But no pressure, as I slowly work through the tax angles on this HVAC equipment replacement decision.  And bring somebody in for another quote for new equipment. And maybe, eventually, get everything working again.

If nothing else, this whole episode shows me that it’s good to have multiple heating systems in your home.

Even with one heat pump dead, we have some heat.

And that is way better than no heat. Continue reading Post #2036: Replacing my heat pumps III: The tax angles.

Post 2035: Oh for ducts’ sake!

 

This is a further installment in my two-dead-heat-pumps, gonna cost me $50K and up to fix it, saga.

Today’s punchline.  My 1959-vintage first-floor HVAC ducts are, objectively, way too small to work with a modern heat pump.  The main duct is roughly one-third the size (cross-sectional area) it needs to be.

We could put the best ground-source heat pump in the world at one end of those ducts, and the kitchen at the other end of the air duct would still freeze in the wintertime.

If feasible, we’re going to replace (one of) our dead ground-source heat pump(s) with a couple of ductless mini-split air-source heat pumps.  Just bypass the grossly undersized ducts entirely.

Sounds like a fundamentally stupid thing to do.  But not so, in this case.  I think.

Never make fun of the size of a mans ducts.

I finally got the bright idea to measure the size of my first floor ducts.  The ones that barely function. Admittedly, guessing about it was more fun.  And even if I knew the dimensions, figuring out the “right” size is an engineering black art.

But I had a hunch that a quick ballpark answer would be good enough.  The main duct measured out at 0.75 square feet in cross-sectional area.  The first floor of the house is about 1500 square feet.  Per two on-line rules of thumb, the original 1959 ducts are about one-third as big as they need to be.

That squares with the rest of it.  Not just their abysmal air delivery, but just by eye, the cross-sectional area of the main duct is about a third that of the plenum to which it is attached.

I can easily believe that the folks who originally installed my ground source heat pump installed a super-duper ground-source heat pump, then blithely hooked it up to grossly undersized duct work. It’s of-a-piece with the rest of the shoddy retrofit they did before selling the house.

But the ducts themselves appear to be much, much older.  They’re behind plaster walls, for one thing, and I’ll swear that plaster has never been disturbed.  They are in an unusual configuration, with both ground-level ducts, and ceiling-level ducts that must be fed by long risers.  The guy who built this house seemed to build pretty good houses.  How’d the original builder manage to put in such goofy undersized ducts in the first place?

I now think that these first-floor air ducts were originally designed and sized for use with a gas-fired hot air furnace.  The air coming out of one of those is very hot, and so quite energy-dense, compared to the lower-temperature air you would typically get with a heat pump.  Not only would you have to move less air to heat an area (thus requiring smaller ducts to move it),  you probably got a considerable “chimney” effect in the vertical risers that serve the many ceiling-level vents.  (Vents that, in the current system, seem to do absolutely nothing.)

In the end, it doesn’t matter.  A few simple checks all tell me that they are, in fact, just way too small for use with a modern HVAC system.   

Twenty years ago, they cut a major corner in the original ground-source installation.  For 20 years, system performance must have been sub-par as a result.  For sure, for 20 years, the kitchen has been freezing cold every winter.

It’s time to fix that as best I can.

Rule number 4:  Yes, they really can be that stupid.

 

A buddy of mine once gave me a little laminated list of rules for life.  Rule number 4 was as stated above.

At root, my biggest problem so far with this two-dead-heat-pumps fiasco is forgetting Rule #4.  Because, when I bothered to check, sure enough, the folks who retrofit this charming home with a super-expensive ground-source heat pump system then proceeded to hook one of those heat pumps up to grossly undersized ductwork. Which made the entire point of installing an efficient heat pump almost completely irrelevant.

And so it has remained for two decades.

And now, completely contrary to the conventional wisdom, it makes sense to  replace a worn-out ground source heat pump with an air-source heat pump.  If for no other reason than to bypass the undersized ducts.

Addendum:  Or duck the ducts.

I finally got it.  The story ends … and you can’t replace the duct, because a properly-sized main duct would stick down too far in the basement.  So not only didn’t they replace the ductwork, they couldn’t replace the ductwork without losing standing headroom right down the middle of the finished basement.

This situation is no-one’s fault.  It is what it is.  Deal with it.

Post 2032: Replacing my heat pumps, part II: How efficient are my ground-source and mini-split heat pump options?

 

The key question for this post is about as simple as it gets: If I have two choices for heat pumps, which one will use less electricity?

In my case, one option is the replacement ground-source heat pump that has been recommended, at a base installed price of about $25K per heat pump.  The other option is to replace my dead ground-source heat pump with a modern air-source mini-split heat pump, at somewhere around half that cost (call it 60% after adjusting for likely difference in equipment life, in my particular case).

This is a stupidly hard question to answer well.  As I explain at length below.

But, after doing all the homework that I care to do, for my house and my climate (with mild winters and an efficient gas-fired secondary heating system), the answer is that either style of heat pump (air-source or ground-source) will use roughly the same amount of electricity.  Or near as I can tell, based on published data.

That’s not due to the underlying physics of the situation.  If it were only about the physics, ground-source would win hands-down.  Instead, that appears mainly due to faster technological improvement in air-source units over the past decade or so, compared to ground-source units.  This seems to have fully offset the “natural” advantage of ground-source.  In effect, my real-world choice is between air-source using the current generation of technology, and ground source using older technology.  (The model of ground-source heat pump I have been offered was first introduced in 2016.)  Or, at least, using a less-efficient design for the heat pump itself, disregarding which heat sink (air, ground) is used.  That’s what makes it a tie ballgame, as of now.

This leads me to conclude that replacing one of my dead heat pumps with (e.g.) a name-brand air-source mini-split system:

  • Is substantially cheaper, even accounting for likely shorter equipment life.
  • Incurs no significant loss of efficiency compared to my ground-source option.
  • As a bonus, bypasses my house’s barely-functional 1959-era ductwork.

Ground source systems still have some clear advantages.  All the equipment is indoors, and so likely lasts longer.  They work well even extremes of cold or hot weather.

But the fact is, there just ain’t that many of them, particularly in a relatively mild climate like Virginia.  Of the roughly 4 million annual residential heat pump installations per year (in 2022), maybe 50,000 (call it 2.5%) were ground-source units.  That has big implications for how rapidly the units reflect improved technology, and how much choice you have for who installs and services your unit.

Unless some unforeseen problem arises, I will replace one three-ton dead ground-source heat pump with a pair of 1.5-ton mini-split air-source heat pumps.

And I will not feel the least bit guilty about doing so.

I was going to give full and excruciating details but the overall accuracy of the conclusion does not warrant that.  Below, I sketch out enough to summarize how I arrived at the numbers above.

SEER, EER, HSPF, COP, and all that jazz.

The efficiency of a heat pump varies, based on the how big a temperature difference it is trying to pump against, and how close you are to the maximum capacity of the system.  The bigger the temperature difference, and the closer to maxed out, the less efficiently the heat pump runs.

This means that, despite what you read from many internet sources, you cannot simply convert one heat-pump efficiency measure to another with a simple conversion-of-units number.  Yes, you must do that first, because some of these measures mix BTU/Hs and watts, and others don’t.  But in addition, you also have to make some sort of adjustment for how stringent the test is.

It’s very much like EPA mileage.  The MPG the EPA gets depends on how the car is driven.  Typically, EPA city mileage is much worse than EPA highway mileage.  If you compare the city MPG of one car to the highway MPG of another, you’re making a mistake.  So it is, in spades, with SEER, EER, COP, and HSPF.

Now we get to the hard part:  Things are hazy.

If you Google SEER, say, you’ll see the same zero-details definition everywhere:  It’s the ratio of the cooling power produced (in BTU/H), to the electrical power supplied (in watts).  But as to, how, exactly, that’s measured, it’s hard to find any information at all.  E.g., is the energy used to run the water pumps included, what indoor and outdoor temperatures were used for the test, how were ducts, water pumps, etc. factored in, and so on.

  • The details of the tests are proprietary and reside behind an expensive paywall.
  • For the same measure, ground-source and air-source heat pumps use different methods.
  • Certain aspects of overall energy use — duct system back pressure, water pump electricity use, and resistance electrical heating for backup heat — are either ill-specified, or not stated as to impact.

Among the things that I’ve seen hints for, but no definitive answer, is how these tests treat the waste heat of the electric motors themselves.  I saw at least one credible-looking website showing that ground-source heat pumps add the value of this waste heat to their heating output, as if that heat would make it into your ductwork.  But air source heat pumps do not.  That’s consistent with where the compressor is located (inside for one, outside for the other).  But it boils down to an assumption that the waste heat of the compressor motor somehow warms the air in your ductwork, which clearly isn’t the case for the units in my basement now.  I have yet to find a clear answer on that, and it matters materially to the comparison.

So you need to take the table above with a grain of salt.  My interpretation is that if there is a difference in efficiency across the three units I looked at, it’s small.

Definitions

Each of these measures compares output heating or cooling power, to input electrical power used.

EER (energy efficiency ratio).  Cooling.  Measured at a steady 35C outdoor air temperature, 26C indoor air temperature, and 50% relative humidity (for the outdoor air?).  Heat/cool is measured in BTU/H, electricity is in watts.  I think the test calls for the unit to run full-blast when this is measured.

SEER (seasonal energy efficiency ratio).  Cooling.  Near as I can tell, this is set up to simulate the range of temperatures you would see in a “standard summer”, so to speak.  Heat/cooling power output is measured in BTU/H, electricity input is measured in watts.

COP (coefficient of performance):  Heating:  Generically, COP is simply watts of heat out, divided by watts of electricity used.  Heat pumps have different COP values depending on the temperature tested, and how hard they were running.  But the EPA-reported COP appears to be for one temperature, and I think its with the unit running full blast.  Heat/cooling power is measured in watts, electrical input power is measured in watts.

HSPF (heating seasonal performance factor).  Heating.  Like SEER, this tests the units over a range of temperatures designed to be a sort of “standard winter”.  I believe that, where the unit has a resistance-heating secondary heater, if that clicks on during the testing, the electricity used in secondary heating is counted toward the total.  Heating power is measured in BTU/H, electrical use in watts.

The -2 suffixed versions of these appear to include a more realistic measure of the back-pressure of typical home ducts.  Best I can tell, in the typical situation, you’d expect the (e.g.) SEER2 rating of an appliance to be 5% to 10% lower than the SEER rating.

Accounting for test stringency:  SEER to EER conversion, units-adjusted HSPF to COP conversion.  Here, I found some sketchy internet sources suggesting that where you have SEER and EER for the same unit, SEER is typically 85% of the EER value, due to the more stringent testing cycle.  So I used that to adjust these all to a common EER-style basis.

Conclusion so far

Again, take this table with a grain of salt. There’s a whole lot I don’t know about the details of how each test is applied to each type of machine.  And probably never will know, particularly for the details of testing ground source machines, where tests specifying outdoor air temperature are irrelevant.

That said, if you adjust for the difference in units-of-measurement (BTU/H versus watt), and assume that the tests that use a broad range of conditions (SEER, HSPF) tend to run about 85% of the equivalent tests that use a single set of conditions (EER, and COP as EPA reports it), then you get the comparison above.

Which, honestly, is just about what I came up with, back-of-the-envelope, when I first looked into this some years ago.  The super-high-SEER Japanese-made heat pumps that emerged a decade ago seemed to eclipse (my estimate of) my existing ground-source heat pump’s efficiency.  SEER 25? Maybe I mis-recall.  But I do recall being startled with how high the available SEER ratings got, for air-source units.

Bottom line, efficiency-wise it’s a tossup.  If I weight each units two numbers by local degree-day (3x heating a cooling), I get my estimated all-year efficiency values of 3.6, 3.5, and 4.0 for the three heat pumps examined, respectively.)

If your location experiences lot of time at extremely cold or hot temperatures, ground-source heat pumps still seem to offer some significant efficiency advantages over air-source.  And, for sure, because the equipment is all inside, ground-source is likely to last longer.

But in my case — with a relatively mild climate, efficient (gas-fired) backup heat, and so on — it’s six of one, half a dozen of the other.

Finally, this pretty strongly suggests that the current tax law is out-of-date.  The huge advantage given to ground-source heat pumps might have made sense in 2004.  It appears to make no sense in 2024.

Once upon a time, ground-source heat pumps were king.  But not any more.  And the law has yet to catch up with that.

Post 2031: Both of my heat pumps have died? This should be interesting.

 

 

My house is heated and cooled by two ground-source heat pumps, installed by the previous owner almost exactly 20 years ago.

Well, “was heated and cooled”.  One died last spring.  The other has one foot in the grave, with its most recent repair involving some burned wiring (never a good sign).  Both heat pumps need to be replaced. 

No-brainer, right? Just replace them.

Well …

The only firm in my area that specializes in ground-source heat pumps quoted me a price of $50,000 to replace my two three-ton (ground-source) heat pumps.  That’s for the basic model.  Bells, whistles, and line sets extra.  I’m guessing the final cost would end up around $60K.

 

At this point, the only thing I know for sure is that no matter what, this home repair is going to be about like buying a new car.  Or two.

Minus the fun.

Follow along for the next several posts, as I get a handle on what to do next.

Am I a heat-pump heretic?

I drive an EV.  Cripes, it’s a made-in-USA Chevy EV, for that matter.

I re-calculate my family’s carbon footprint every couple of years.

And I bought my house specifically because it had efficient ground-source heat pumps.

But the world continues to change.  And I’m not sure I’m going to be replacing those with new ground-source heat pumps.

And the fact that I would consider not doing that makes me something of a heretic.  But I’m still in the process of gathering my facts.

  1. Twenty years ago, ground-source was the undisputed king of heat pumps.
  2. In part, that’s because air source heat pumps of the time weren’t very good.
    1. They worked inefficiently when it was cold out.  To the point of essentially not working.  That caused use of “secondary heating”, meaning, typically expensive and inefficient resistance electric heating.  In winter, your fancy heat pump spent too much time operating as more-or-less a big dumb electric space heater.
    2. And they weren’t any great shakes, efficiency-wise, the rest of the time.
    3. Plus, they just kind of generally sucked.  Comfort-wise.  In the winter, they always seemed to blow air that was, upon careful measurement, slightly warmer than the existing room air.  Or, at least, that’s how I recall my Maryland apartment of the mid-1980s.
    4. Basically, they were air conditioners that, in this climate (Virginia), could also put out some heat, for some of the winter.
  3. My impression is that this changed about ten years ago.  At some point, cutting-edge air source heat pumps appeared to be — by my calculation — at least as efficient as my 2004-vintage ground source heat pumps.
  4. That’s because air-source technology improved rapidly, while the technology of ground-source units … lagged?
    1. Part of the improvement was in finding a way for air source heat pumps to function well even at low outdoor temperatures.
    2. That went hand-in-hand with greater efficiency of operation.  E.g., modern air-source units might now have variable-speed compressors, fans, and so on.
    3. But not much seems to have happened to ground source heat pumps.
    4. The slower rate of improvement in ground source heat pumps is a side-effect of the vastly lower volume of ground-source (about 0.5% of the home market) compared to air-source (the other 99.5%).
  5. As a result, ground-source heat pumps are no longer a slam-dunk winner, compared to traditional air-source heat pumps.

    1. As a matter of basic physics, they should be.
    2. But because they seem to be behind the curve in efficiency improvements, they aren’t.
    3. The upshot is kind of a temporary tie:  The rapid adoption of more efficient technology in the air-source sector has offset (or nearly offset) the inherent physics-based advantages of ground-source heat pumps.  For now.
  6. There is no point number 6.
  7. But the tax laws still grossly favor ground-source heat pumps over air-source.  And the subsidies are large.
    1. For ground source, the Feds pick up 30% of the installed cost, no limits.
    2. For air source, if it meets certain efficiency standards, the Feds pick up a maximum of $2000 (or 30% of the installed cost, whichever is less).
    3. And Virginia offers an incentive system for ground-source that is beyond weird, and must be described in a separate posting.  At first blush it appears ludicrously generous toward ground-source units.
    4. Separately, I’m not sure they were thinking about replacements of worn-out old systems when they wrote the law.  Effectively, what I’m doing is repairing my existing system, by replacing the worn-out heat pumps. But, legally, that’s treated identically to putting in a brand-new ground source heat pump system.
  8. So, something is not right here.
    1. Is the law outdated, and out-of-step with the current state of technology?
    2. Or is the law a closet buy-American plan, as these ground-source units seem to be U.S.-made?
    3. Or am I dead wrong about the near-equivalence of air-source versus ground-source efficiency in the modern world?
    4. Or, some thing even weirder — geothermal versus ground source discussion to be added at some point.
  9. Curveball:  My first floor would be ideal for a couple of “ductless mini-split” systems.  These are little air-source heat pumps, but instead of being designed to hook up to your ductwork, they simply blow air around like a room air conditioner.  You pass the refrigerant pipe and condensate drain through an exterior wall, between the inside air-distribution cabinet, to the outside compressor.
  10. So, why not replace one of the dead ground source heat pumps with two mini-split air source heat pumps, half the size.
    1. Near as I can tell, I’d pay only a modest or no efficiency penalty for doing that.
    2. And it looks like it would be quite a bit less expensive, even accounting for likely shorter equipment life of an air-source system.
    3. Plus, we’d possibly have a warm kitchen for the first time since we moved here, because we could bypass our near-useless 1959 first-floor ductwork.
    4. Plus, it’s lower risk — more like an appliance, and less like a fixture in the house.  If one of those dies, I can just toss it and more-or-less just plug in a new one.  Not quite as convenient as a fridge, but not hugely different.
  11. But … but … but … the very thought of replacing a ground-source heat pump with an air-source heat pump is … heresy.  Particularly given that the actual “ground” portion of the ground-source system — the mile of plastic “slinky” pipe buried in my back yard — still functions perfectly.

Conclusion

That’s as far as I can take it in this first post.  I need to pin down some facts to go any further.

I bought this house in large part because it had an efficient ground-source heat pump.

But the world has changed since I bought it.

The next post takes the two real-world heat pumps — one a ductless mini-split air source heat pump, one the ground-source heat pump for which I have been quoted an installed price — and tries to get an apples-to-apples comparison between them, in terms of efficiency.

That turns out to be stupidly hard to do.

That’ll be the next post:  SEER, SEER2, EER, EER2, COP, HSDF and all the rest of that alphabet soup.  And how on earth they measure that, for ground-source heat pumps.

Post #2010: PFAs, the revenge of Freon

 

Per- or Poly-fluoro-alkyl substances (PFAs).  They’ve been in the news of late.

This post is a quick refresher on PFAs. For me.  I’m just trying to get my facts straight before seeing if a need to change anything in my life to try to avoid PFAs.

Short answer is no, but more from lack of information than for any positive reason.

Part 1:  An easily-digested chemistry lesson.

Source:  An on-line chemistry course from Western Oregon University.

Alkanes are chemicals consisting of nothing but carbon and hydrogen, where the carbon atoms are “saturated” with hydrogen.  (That is, there are no high-energy “double bonds” or “triple bonds” among the carbon atoms.)  The carbons can be arranged in a straight chain, a branched chain, or some form of circle.  You are already know the names of some common straight-chain alkanes, above.

Aside from the fact that we can burn them as fuel, most common alkanes are unremarkable.  These substances are produced routinely in nature (insert fart joke here) and will break down naturally.  For example, the half-life of methane in the atmosphere is somewhere around 10 years.

But if you can take those run-of-the-mill alkanes, and somehow substitute fluorine atoms for hydrogen atoms … magic happens.

For example, the single most-common plastic in the world — polyethylene — found in milk jugs world-wide, becomes the slickest substances in the world — Teflon.

 

The quick upshot is that whenever you substitute fluorine for hydrogen in these long-chain carbon compounds, there’s a good chance you’ll end up with something that’s pretty cool.  Something that is:

  • completely inert (Halon). or
  • works as a refrigerant (Freon), or
  • produces a nearly-frictionless surface (Teflon), or
  • makes fabric waterproof and oil-proof  (Scotchguard)

The root of all of that is this:

Source:  Chemtalk.

All these magical properties — inert, un-wettable, nearly frictionless — derive from the same source.  Fluorine is the most electro-negative element in the known universe.  That is, among all the elements, fluorine has the strongest attraction to electrons held by other atoms. 

The upshot is that if you can manage to get fluorine to bond with carbon, it stays bound.  It takes a large amount of energy to break that bond, precisely because fluorine wants to hold onto those carbon electrons more than any other element does.  Better yet, that property of being tightly bound spreads to the adjacent carbon atoms, to some degree, so that much of the entire molecule is really strongly stuck together. 

It is no small trick to create fluorocarbons in the first place.  It takes more energy to get a fluorine atom hooked onto a carbon than it takes to get any other suitable element to do that.

This is why there are almost no naturally-occurring fluorocarbons.  I just read that the count stands at 30 such, in all of nature.   And many of the naturally occurring fluorocarbons are produced by a single family of exotic tropical plants.  You are guaranteed scientific publication if you discover a new one.  Correspondingly, nothing in nature has evolved to digest or decompose or otherwise deal with fluoro-carbon compounds, which is why all the plants in that family are incredibly toxic.

Sometime, when you want to feel uncomfortable, read up up what happens if you have any significant contact with hydrofluoric acid.  That intrinsic property of free fluorine is part of the problem.

In short, once you manage to substitute fluorine for hydrogen in a carbon compound, you end up with something that doesn’t want to interact with any other chemicals.  Not water.  Not oil.  Not nothin.  The very properties that make PFAs desirable as industrial chemicals — inert, waterproof, oil-proof, slick — make them virtually indestructible in the natural environment.

In any case, given their properties, it’s not too surprising that we use a lot of them.  I see a 2021 estimate from the EPA that we produce at least 85,000 tons of PFAs in the U.S. annually (Source:  EPA-821-R-21-004, Page 5-3).  If I did the math right, that’s (85,000 x 2000/330,000,000 =) at least a half-pound per person per year, in the U.S.  And I’m pretty sure that was a partial inventory.

 

2: PFAs: The best of Freon and DDT.

Source:  Socratic.org

“If those chemicals don’t break down under ordinary conditions”, you might reasonably ask, “then where do they end up?”

Seems like modern industrial society has asked that question a number of times now.  And, somehow, the answer is never good.

Start with Freon.  Any flavor of Freon.  If Freon is inert, where does it end up?  The answer for Freon is that it only diffuses into the air, until, some decades after it was released at ground level, it gets broken up by high-energy UV-C radiation in the upper atmosphere.  There, the fragments of that former Freon turn out to be quite good at thinning out the earth’s protective ozone layer.

The twist for PFAs is that they start with the same near-indestructibility of Freon, and tack on the food-chain-accumulation properties of DDT. And in this case, we’re squarely at the top of that food chain.  In addition, PFAs are eliminated from the body quite slowly — I see casual estimates of two to ten years.  Given all that, it’s no surprise to find that 97% of Americans have detectable levels of PFAs in their blood, based on the National Health and Nutrition Examination Survey circa 2007.

Having high levels of this stuff in your blood — say from occupational exposure, or consuming something heavily contaminated — is undoubtedly bad.   I’m not so clear on what the expected health effects would be at typical population exposures.

Part 3:  Action items?

To cut to the chase, no, not really.

You can find advice in this area, but it all appears to be, of necessity, total guesswork.  The fundamental problem is that there is no good assessment of where typical population exposure comes from.  Not that I could find, anyway.  Which means that you have no way to know what’s actually worth avoiding, and what’s somebody’s list of things that might contain PFAs.

For some of these, though, it’s clear that when the Feds started getting them out of consumer products, the average concentration in the blood of Americans began to fall.  Like so, from the CDC, showing U.S. population blood levels of PFOS (perfluorooctane sulfonate, top line) after the EPA orchestrated a phase-out of use of that chemical in the US.

Source:  US CDC

On the typical list of things to avoid, you’ll see Teflon frying pans and stain-proof/waterproof fabrics. I’m not sure about the extent to which the PFAs in those types of products actually end up in your blood.

But there’s a surprising amount of common skin-contact and food-contact material that may have more mobile sources of PFAs in it.

Waterproof cosmetics and sunblocks are on everybody’s list.  Although I sure can’t find any that plainly contain -fluro- chemicals listed.  I just checked a couple of bottles here, and many examples on Amazon, and I see nothing that I would recognize as a PFA.  Plausibly, if those contain PFAs, they are inactive ingredients, and so typically aren’t listed?

But also grease-resistant food packaging, including pizza boxes, french-fry bags, hamburger wrappers, paper plates, microwave popcorn bags, and so on.  Basically, a whole lot of stuff associated with take-out food.  All because a lot of grease-proof paper/cardboard coatings contain PFAs. This Consumer Reports article was illuminating, and names names among fast-food restaurants.

Some cooking parchment paper has PFAs to make it extra slick.  Some cleaners and waxes have PFAs.

But aside from “don’t eat fast food”, none of that seems terribly actionable.

For drinking water, of course this stuff is in drinking water.  At least here, where around 10% of what’s flowing past the water intakes here in the Potomac River at Washington, DC came out of some sewage-treatment plant somewhere upstream.

It appears that either activated-charcoal or reverse-osmosis filters will remove PFAs.  (That makes sense, because both of those technologies are good at removing large organic molecules.)  No pitcher-type water filters remove PFAs.  Oddly, I read that distilling water doesn’t remove PFAs either, though I have no idea why not.

4:  Conclusion

My interest on PFAs was piqued by NY Times reporting that sewage sludge used as fertilizer passes PFAs from the sewage stream onto the land, to the plants grown on the land, to (in this case) the cows that eat those plants, and ultimately to people.

This is not news, really.  There have been several EPA actions on PFAs, including cajoling industry into phasing out what appeared to be the worst PFAs. Even a cursory look shows a long history of EPA interest in monitoring these chemicals.

What caught my eye is the case of a farmer whose land was condemned for food production, due to toxic levels of PFAs in the soil, toxic enough to sicken the cattle grazing on that land.  This, where the only plausible source for those PFAs is sewage sludge that has been spread on that soil.  And since PFAs don’t break down, for all intents and purposes, the land is forever condemned for food production.

That’s unusual.  Or, at least, you rarely hear of that out side of EPA Superfund sites.

But in terms of action items, for avoiding eating and drinking PFAs, I’m not seeing a lot of quantitative advice on what to do.

So, in the absence of any better information, I’m just going to put this one on my list of all the things I dislike about the modern world, but that I can’t do anything about.

Post #2004: Switching to sugar-free credit cards. I mean cutting boards.

 

This post is briefly explains why I’m tossing out my worn plastic cutting boards and mats, and rehabbing a few wooden cutting boards to take their place.

This, based on two absolutely ridiculous research findings regarding the amount of microplastic in the diet, as measured in credit cards per year.

This will all make sense by the time I’m done.

A ratio of credit cards.

A few weeks back,  you may have read that the average American eats a credit-card’s-worth of micro-plastic a week, on average.  The obvious click-bait potential for such a bizarre and gross assertion meant that it got lots of attention on the internet.  (The research has been around for a while, but for some reason, there was a recent resurgence of reporting on it.)

I’m not giving a reference for that, because, as discussed below, that’s total 💩.

But, because normal isn’t newsworthy, you’d be hard-pressed to find any internet mentions of the the debunking of that credit-card-a-week.  Other scientists have taken the same (~) underlying data and calculated a weight of microplastic in the diet of around one-millionth of a credit-card a week.  Just under five millionths-of-a-gram per week, not five grams per week.

(How?  To be as charitable as I can, it turns out to be difficult to take counts of a few dozens of microscopic plastic fragments, in a few samples of food, and extrapolate those data to come up with the total weight of microplastic in the diet.  As I read the scientific debate, the authors of the various “credit-card” studies simply made an exceptionally poor choice of extrapolation method.)

Now, you personally may have thought that that “credit-card-per-week” figure was implausible.  And yet, because “microplastic in the diet” is such a squishy entity (starting with, invisible), you really had no way to prove that your instincts were correct.

Now, thankfully, somebody has jumped the shark.  There’s a  new study claiming that, in addition to plastic in the food chain, the use of plastic cutting boards adds a further ten credit-cards a year of plastic to the diet.(?)(!).

FWIW, this is the cutting board analysis refernce  The piece that points out the problems with the 52-credit-cards-a-year analysis is this reference.

The cutting-board estimate estimate is also total 💩.  But it’s useful 💩

💩 ?  Yep.  Same reason as the credit-card-a-week study.  See above.

But its useful in the following ways.

First, this most recent “credit-card-consumption” study is self-debunking for the average user.  Because, while I’m not exactly sure what “microplastic in the diet” looks like, I for sure know what a plastic cutting board is.

Do the math, and at 5 grams per credit card, ten is just shy of two ounces a year.  This research is claiming that the average person’s plastic cutting boards erode from knife cuts at the rate of (~) two ounces/year/household member.

Really?  For your consideration, I offer Orange Cutting Mat (below), weighing in at a svelte 1.1 ounces:

If the erosion rate really were two ounces a year, the mat above would have been worn to shreds a decade or two ago.  It’s old.  Origins are lost in the mists of history.  It’s used more-or-less daily.  It’s obviously scratched from use.

And yet  this venerable cutting mat continues to serve.

Worse — and for shame — the authors of this 10-credit-cards-a-year study could have convincingly debunked their own finding with a day of work and a kitchen scale.  Weigh a cutting mat (per above, 32 grams).  Chop vegetables on that mat for five hours (300 minutes) to simulate 30 days of typical household chopping.  If the estimated two-ounces-per-year is correct, you’ll have lost about one credit-card’s-worth of plastic, or about 5 grams.  At the end of the day, if the erosion rate was as-stated, that plastic mat ought to weigh just 28 grams.  That amount of plastic weight loss should be easily detectable on a gram kitchen scale.

In other words, you can literally check their work by subtraction.  With a kitchen scale.  And a month’s worth of vegetable.  And some manual labor.  Just weigh the cutting mat pre- and post-  a marathon cutting session.

But as importantly, this study makes you realize that, yep, some of the plastic from those scratches is exiting as tiny fragments.  And you’re eating those tiny plastic fragments.  Some of them, anyway.  There’s no reason to think that the authors did their lab work incorrectly.

And, if you follow the thread here, because 10/52 =~ 20% based on the well-known Universal Law of Credit Card Accounting, using plastic cutting boards ups your dietary consumption of microplastic by 20%.  Or so.  Under the assumption that both studies embody the same degree of (gross) overstatement of the actual weight of plastic.

I don’t know whether the actual amount of microplastic in the diet causes significant harm or not.

On the one hand, humans have been using copious amounts of plastic for decades.  If there is some health hazard from microlastic in the diet, chances are good that it has already occurred.  I suspect we’re hearing a lot about microplastic due to some change in technology that makes it easier and cheaper to detect.

(Take that cynicism with a grain of salt, as my entire house is carpeted in cut-pile polyester wall-to-wall (Post #1943, carpet fiber burn test).  And, accordingly, I must surely live in veritable airborne-microplastic-polyester-fiber-fragment miasma.)

On the other hand, you at least have to recall the mechanism of action of asbestos for lung cancer.  My recollection is that it was a micro-fiber disruption argument, The fiber in question, thought to spur generation of lung cancer, was an eensy asbestos fiber fragment that got inside the lung cell.  And proceeded to screw up the works just enough, when that cell next divided.  That’s how I recall the theory of it.

So, durable microscopic fibers (or other plastic bits) can’t be readily dismissed.  Plausibly, it only takes a tiny amount of that stuff to cause whatever havoc it’s going to cause.

Conclusion:  Putting the ick in clickbait.

The upshot is that while the jury’s out on the dangers of microplastic in the diet, there’s no sense in force-feeding yourself with it.

Not when you can easily cut your food up on something else.

As final insult to injury, I note two things.

First, as I read it, based on the underlying data used, that 10-credit-cards-a-year from use of plastic cutting boards would be in addition to the estimated 52 credit-cards’-worth already supposedly in the diet.  So the purported total now stands at 62 credit-cards a year, for those who both eat food and use plastic cutting boards. 

Second, I infer from this glimpse of the literature that there’s a whole slew of scientific papers in the pipeline that use minor variants on this same (bad) extrapolation methodology.  So, changes are, there’s now going to be a string of articles showing the mind-boggling amounts of microplastic you eat due to fill-in-the-blank.  These will, of course, be rapidly popularized on the internet, because they put the “ick” in clickbait.  Literal accuracy is not required, only some plausible (i.e., science journal) source.

Post #1999: Power outages aren’t what they used to be.

 

A couple of days ago, we lost power for a few hours in the the aftermath of hurricane Debby, as it moved up the coast.  I took a walk during a break in the rain and found that a tree had split, bringing down some power lines a couple of blocks from my house.

Here are a few observations, sitting on my back porch, waiting for the power to come back on.

1:  It’s noisy around here when the power goes out.

Source:  Electricgeneratorsdirect.com

Used to be, power outages brought some quiet to the ‘burbs.  If nothing else, in the summer, all the AC compressors shut off.

But now, I can barely hear the wind in the trees over the droning of home emergency power generators in my neighborhood.  Instead of a bit of idyllic quiet, it suddenly sounds like I’m in the middle of a busy construction site.

All it lacks are the back-up beeps.

Unsurprisingly, these are all attached to the gi-normous McMansions that have sprung up in my neighborhood over the past decade.  (See my prior posts on the “tear-down boom” in Vienna VA.)  I’m guessing that about one-in-three of these new houses came with a permanently-installed natural-gas-fired generator.

The instant the power goes out, instead of quiet, you hear generators kicking in all over the neighborhood.   I can hear at least three, from my back porch.  Those turn on automatically, and won’t shut down until the power comes back on.  No chance they’ll run out of fuel, because these are connected to the natural gas supply.

It’s not as if my neighbors suddenly had some sort of preparedness mania.  They didn’t rush out and buy big home emergency generators in anticipation of the next snowpocalypse.  It’s that if you’re going to pay $2 mil for a house with all the extras (home theater room, sunken walk-in closets with windows, wine room, and so on), the $10K cost of an installed generator is rounding error.

So this is how power outages will sound in my neighborhood, for the rest of my life.  And as more small houses are torn down and replaced by as-large-as-the-law-allows McMansions, the density of emergency generating units is only going to go up from here.

2:  What is the sound of one reefer idling?

Now we get to the truly annoying part.

Near as I can tell, these new-fangled generators all seem to be old-school direct-drive units.  That is, an internal combustion engine (burning natural gas, in this case) is directly coupled to a generator creating alternating current (AC).

With that setup, the speed of the gas engine determines the Hertz (frequency) of the AC voltage.  The gas engine must therefore run at constant high speed to maintain 60 Hertz (cycles-per-second) AC.  That’s achieved by a governor that tightly regulates the speed of the engine.  At low electrical load, the engine runs just as fast and as loud as at high load, it just strains less to keep the generator spinning.

To a close approximation, these things are every bit as loud at idle — with no significant electrical load — as when they are putting out their maximum rated load.

The upshot is that each one is about as loud as a refrigerated truck.

So, instead of a bit of quiet, a power outage now means that my neighborhood sounds like a bunch of big diesel trucks are parked here,running at high idle.

3:  Where was I?  Ah yes, thrum-thrum-thrum.  Quiet emergency generators, explained.

So, as I sit on my back porch, enjoying the breeze and listening to the throb of my neighbor’s emergency generators,I figure I should explain the concept of “quiet” inverter-generators.

With an inverter-generator, the gas (or natural gas) engine turns a generator that generates DC electricity,  which feeds a piece of power electronics called an inverter, which then electronically generates the required 120 volt 60 hertz AC.

For that style of generator, there is no link between the speed of the gas engine and the frequency of the resulting AC (house) voltage.  This means that under light load, the internal combustion engine can slow down, and for any power demand, can be run at the speed/torque combination that most efficiently produces the required power output.

So inverter-generators are both more efficient, and on average quieter, than old-school direct-driver generators.  Though you will hear the engine speed change if there is a material change in the electrical load placed on the inverter.

Old-style direct-drive generator units are simpler to make than inverter-style generators.  But they are inherently less efficient, and, it seems, intrinsically louder, on average.  In any case, modern inverter-style generators have taken over the small-portable-generator market, specifically because they can be marketed as “quiet” generators.

4:  Direct-drive generators, inverter-generators, and three-legged-dog generators.

But my neighbor across the street, and one house up, seems to have purchased the worst possible kind of emergency generator.  It’s a maintenance-free natural gas generator that nevertheless runs like a three-legged dog.

The engine on that has kind of a ragged one-cylinder miss.  Which means that the engine speed and sound are constantly changing.  Which means the noise doesn’t fade into the background, but is constantly noticeable.  Particularly if you know anything about how an internal combustion engine is supposed to sound.

The result is an impossible-to-ignore loud thrumming noise, originating about 50 yards away.

Worse, while it sounds like it has a fouled spark plug, if I listed closely, a) the miss is a little bit too regular, and b) it seems to stop briefly from time to time.  I’m guessing this may be how the engine is supposed to run, and that it purposefully shuts down a cylinder under low load.  (I recall that GM tried such a strategy with some V8s, where fuel flow to half the cylinders could be cut off (e.g., when cruising at speed on the highway, where horsepower demand is low.)

So I think that not only am I being treated to the relentless thrumming of this generator for this outage.  I think that’s actually the way the thing is supposed to run.  So that I will be treated to this delightful noise every time the power goes out, from here on in.

I guess if I don’t like it, I can just hole up inside.

I may be without power for a while.

Maybe I need a my own whole-house generator.  That way, I can sit inside, in the AC, during a power outage, like all my neighbors.

4:  Quieter emergency power?  Hybrid-or-EV-plus-inverter, and USB-tethered Wifi hotspot.

For my emergency power source, I keep a 1 KW inverter on the shelf of my garage.  Hook that up to the 12V battery of a Prius, turn the car on and leave it, and run a heavy-duty extension cord from car to house.  The car will start and run the gas engine occasionally, to keep the battery up.  The only sound it makes is the occasional few-minute stretch with the Prius idling.

If the power isn’t back on in a couple of hours, I can set that up so that up so I can run the fridge.  In the meantime, I got around the loss of my FIOS internet by attaching my phone to my laptop, and using my phone as a Wifi hotspot.

5:  Aside:  Of magnetos and bike speedos.

Source:  Amazon.

Weirdly enough, I just installed a generator of sorts the day before this storm.

Old-school direct-driver backup generators are alternators.  That is, they directly convert mechanical motion into alternating current.

New-style inverter-generators are generators.  That is, they convert mechanical motion into direct current.  Which is then converted to alternating current by an inverter.  (Well, technically, a generator is anything that generates electricity, AC or DC.  But if it generates DC, you have to call it a generator, not an alternator.)

And then there are magnetos, something most have only heard about in the context of piston-engine-driven aircraft.  A magneto generates pulses of electricity used to fire the spark plugs of the engine.  It does this by passing a rotating magnet near a densely-wound coil of wire.  A common example is a typical gas lawn mower, where a magnet embedded in the flywheel creates the spark for the spark plug is it whips past a coil mounted a hair’s-breadth away from the flywheel.

And, oddly enough, an old-fashioned wired bike speedometer uses a magnet on the spokes, and a coil of wire on the front fork, to generate pulses of electricity in time with the turning of the wheel, which it then translates to speed.  Not exactly a magneto, but definitely in the magneto family tree somewhere.

6:  Final aside:  Just say no to GPS

Finally, apropos of nothing, bike speedometers are yet another area where the tech changed when I wasn’t looking.  And, in so doing, converted bike speedometers to just another class of disposable electronic devices.

Old-school wired bike speedometers work as described above.  They are, in effect, little magnetos, counting the rate at which a magnet on your spokes creates a tiny little electrical signal as it passes a fixed coil of wire.  In addition to wired bike speedometers, there are old-school wireless ones where the magneto signal is sent via radio waves.  Near as I can tell, these have all the drawbacks of wired ones, and none of the advantages.

But, because these are both old technologies, typical units come with easily-replaced standard button-cell batteries.  Buy a good one — I am partial to the Sigma brand — and they’ll last for decades.  Just change the battery every few years.

And then there’s GPS bike speedometers.  The latest thing.

In theory, this is a step up from magneto-based bike speedos, because there’s no need for any cables.  The speedometer captures a GPS signal, so it knows your location, and can infer your speed.  All for about the same $30 cost as a name-brand wired bike speedometer.

OTOH, owning one of those means that your bicycle now makes a permanent, downloadable record of exactly where you rode your bike, and when.  Presumably, this appeals to people who don’t mind all the involuntary electronic surveillance we already undergo.

But I simply didn’t want to buy yet another device that tracks me.  So, despite the ease of installation (no cables), I took a pass on a GPS-based bike speedometer.

If you immediately got to that punchline as soon as you saw “GPS”, then you get an A.

But, in addition, if you also inferred that these all inexpensive GPS-based bike speedometers have non-replaceable batteries, change that to an A+

And so, as with so much modern small electronics, these devices are disposables.  They come with an embedded USB-rechargeable lithium-ion battery.  When (not if) the battery reaches the end of its life, your sole option is to chuck your old one in the trash, and buy a new one.

Worse, there is clearly no engineering reason for this.  The previous generation of bike speedometers all had replaceable batteries.

It’s just that times changed.  User-replaceable batteries on cheap electronics had already become a thing of the past by the time low-cost bike GPS speedometers came on the market.  And so, if you want a cheap GPS-based bike speedometer, your sole option is to buy a disposable one.  Though, of course, none of them are labeled that way.

Which is how I ended up installing a little magneto-based wired bike computer on my wife’s bike.  It keeps no record of where I’ve biked.  And when the battery wears out, I can replace it.

Conclusion

When one house in a neighborhood has an automatic backup power generator, that’s an oddity.

When every third house has one, it’s cacophony.  As soon as the power goes out, the neighborhood is full of the sound of many loud, small, internal combustion engines, each powering an old-school direct-drive alternator.

I hadn’t realized how bad it had gotten in my neighborhood until I tried catching some breezes on my back porch, during this most recent power outage.  A power outage now makes my neighborhood sound like an overnight truck-stop parking area.

With any luck, maybe this is just a phase these houses are going through.  These days, you can buy a power wall or similar large home storage battery, which then serves as your backup power source.   So that maybe the next wave of oversized McMansions will come with quiet emergency power.

But for now, as small older houses in my area are steadily torn down and replaced by McMansions — where the built-in emergency generator seems to be a popular option at the moment — it’s only going to get louder.