Geothermal heat pumps don''t make sense financially, so why do we always use them?
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- เผยแพร่เมื่อ 7 ม.ค. 2025
- Geothermal Heat pumps are amazing technology... that virtually no one ever uses. Fewer than 1% of houses in the US run on them because they're almost never cost effective.
So why does our company insist on installing them for most of our offgrid house projects?
Simple, geothermal is the best, most effecient heating system for offgrid homes, and saves so much money on solar and battery it pays for itself.
On-grid, it doesn't pencil usually, offgrid it could be the future of housing as we know it.
Welcome to battery builds, where we talk about how to build houses that run on batteries
We have an old air heat pump system as we live in zone 3. Works ok when the temps are moderate, but not so well when it gets well below freezing.
Something I have contemplated to help boost it some, at low cost is the following: Bury a few large copper pipes deep in the ground (in my area, 9 to 10 feet or so). Into those pipes will go highly conductive powders, and some non copper reactive liquid. Then copper tubing, which will be converted into "heat pipe" type tubing will be wrapped around these copper pipes, especially at the base. As the tubing and pipes get closer to the surface, they will be highly insulated.
Anyways, I would probably flatten out this tubing and try to make it have physical contact with parts of the outside condenser unit.
I can't do this, because we have too much shade on our property, but Solar Air heaters are really criminally under used. They are relatively easy to make and install, and can be made quite inexpensively. If you do it right, it can really cut down on the amount of daytime energy you need to use, whether that is electricity, propane, natural gas, wood stove, etc.
Currently we are experiencing a somewhat unusual cold snap with lows into the mid teens and a bit lower. To help my heat pump out, I've put a 15" smokeless fire pit/stove nearish the condenser, put a burn barrel over the top of it (upside down, the bottom has some vent holes on the top and on the sides), and then I wrapped an IR reflective foam loosely around it all (with plenty of space to allow the fan to get enough air and to not over heat the condenser).
Some of the wood is just waste wood from my yard that I can't use in my wood stove because it would create too much creosote, it's too small, or the like. Yes, it is somewhat near the house and may not be fully legal, but I consider this set up much, much safer than an inside woodstove with the potential for chimney fires. Sparks cannot escape this system, and there is no chimney. No, it is not very efficient, but if you're mostly using yard debris, that's not really an issue.
How can you suggest that a heat pump or ANY electrically driven device is better for off grid? When solar panels are your only source of electricity, anything you burn is a much better source of heat. Propane being the most available with little intervention to maintain heat with little or no electricity or human input (loading wood in a stone) which would be cost prohibative if done by PV panels inverters and Batteries
For a cabin, or a small seasonal use house that is the case. Solar is required, but something like an ecoflow delta 4 is big enough.
However once you’re talking about full time use, you need the inverter, the solar and the battery. For cooling, lights etc.
So the question becomes, what’s cheaper? Propane across time or solar and battery across time.
A hybrid approach is often the cheapest, propane and solar together
However, if you wanted a “doomsday” Offgrid house, where propane deliveries would have stopped
Or if you want to build in an area where propane delivery isn’t a viable option
Or if you’re load and runtime in propane was large enough ($1,000-$2,000/yeat)
Then geothermal plus solar and battery start to have a payback compared to propane, plus a propane tank for heating
That's a deep point and telling, about the lack of expertise in the hvac industry. Best route for a homeowner is usually to get an engineer with some experience with similar systems, and pay them to sign off on the design, talk to the inspectors, and check the installation via startup and diagnosis. I agree that done well, geo is an excellent choice where heat or cool needs are at 5 btu tonnes or more.
Yes that is biggest problem in residential building, designing before building is so rarely done, commercial build has to have everything in BIM and every screw, nail accounted for. residential build you can even see moving walls mid build lol. I like "shallow" geo in areas with high water table, that way construction is a lot cheaper with same performance.
Unless you’re using geothermal for thermal storage….
😉
Interesting, factoring battery cost into comparison makes sense, thanks for pov
It’s kind of the only thing we do here :)
Great content. Counter point for you to consider is air source heat pumps keep getting cheaper and more efficient.
A 1 ton mini split can be purchased for well under $1000 these days and the price keeps dropping.
Also, with the switch from r410 to r32 they have picked up some efficiency.
Additionally, pv and battery storage keep dropping in price.
I wonder if 5 years from now geothermal will still be competitive compared to air source, for off grid living
Mini splits are interesting… very cost effective often.
Most are made overseas, and with the new tariffs will likely go up a fair bit in pricing.
The cheap ones generally can’t handle cold climates with high efficiency. So I’d say you get a lot for paying for a nicer one.
Compared to geothermal they lose out as the house and the loads get larger. But for small houses, low loads they’re ideal and super effecient!
I think geothermal going to gain ground mini splits in a lot of markets. Basically mini splits destroyed geothermal sales and geothermal is adopting mini split technology going forward should be quite interesting.
Mini splits struggle to get good air distribution, for higher end homes that’s an issue as well. Curious to see how it evolves going forward myself
Me listening but not looking at 0:54, “just a second sweetie dad‘s going potty.” 🤦♂️
Hahahaha
Dad life - moms got my back
Have a look at heliotherm or other R290 geo thermal heat pump.
I love Nibe, some neighbours have a nibe glycole/water ground heatpump
Also have a look at hydronic underfloor heating, that is a game changer if you want to go of grid. With the water loops in a thick screed layer, it will store the heat energy and slowly release it into the building. Depends on the insulation and outdoor temperatures a room temperature drop of below 1°C over night without starting the heat pump is possible. You charge to floor in the day while the sun is shining
I’m a big fan of hydronic. And concrete screeds in general.We’re trying to permit a house that heats and cools with radiant next month, will definetly have videos to show how it goes
How does the cost change for a horizontal loop instead of vertical?
Vertical is more expensive generally.
We pay $21/ft of borehole plus a mobilization fee of $3500
We typically need between 100ft to 200ft of borehole per ton.
So for a 3 ton system you’re talking $6300-$12,600 plus the mobilization fee.
Backhoe is normally $9000-$10,000 and can be self preformed often
Vertical is typically used when there’s land constraints and horizontal when there isn’t, or during new construction. It can be as cheap as $7,000-$8,000 in the right circumstances (backhoe on site, or installed during over-ex and backfill, to save equipment and people trip to the site)
I think the wrong chart is showing at 6:36
You are correct... thank you very much for pointing that out, i'll update that when i get home later this evening
Geothermal makes sense for cooling in northern areas, but directly, not through running them a heat pump. Air source equipment is so much cheaper for a small off grid house, that geothermal heat pumps don't make sense. But what I'm going to do is that every time I have to dig a trench for some reason, I'm going to run a ground loop in the bottom of it. In the cold spells in winter in the winter, I'll use that to pre-heat air passing past the air source mini split. The rest of the time, I'll use it keep my water from from freezing, and minimizing the night time dip of my eventual greenhouse. Use a wood stove when I'm awake, and a propane hot water feeding a radiant floor when I'm not. My guess is that I'll find out that it is better to cut firewood, then to pay for more propane to run the generator or put in more panels. It is just too cloudy in Northern Idaho!
Geothermal in northern Idaho could be ideal. Especially if you have a septic system. It’s not always a good idea, but running geothermal lines underneath a septic leachfield or alongside a water well line feeding the house are often very good ideas to save money.
Open trenches like your saying are also a great idea many times.
The greenhouse heat load can pair well with the house system. I’d say if you’re already looping and pumping, you may as well use the heat pump as well!
Geothermal is complicatet, in my country (Denmark) geothermal is actually earth heated by the sun in the sommer time so not heat generate by earth. And we always do it in "lines" 3 feet in the ground with 1 to 2 feet in-between.
Geothermal is very complicated
Hoping to make it simpler, I hope you’ll watch our future videos to see how we’re changing the way geothermal is installed in the US markets, and one day Europe
@@alanknudson8774Why is it complicated?
Where I live we don't heat or cool.
The sweet spot, coastal regions are so much fun.
7 solar panels and a car battery is about what it takes to go Offgrid
Where I am from we have 130*F temp swing between seasons and a 6FT deep frost line. Air source is less than useless in my climate. For heat pumps Deep geothermal is only electric option.
Wow - where is that?
@@tcreamer710 Alberta Canada!. at 1000ft we have a 60F ground temp. perfect temp for geothermo. But we need 10ton systems when its -40*F outside
@@tcreamer710 Alberta Canada. at 1000ft deep we have ground temp of 60*F. We need 10 ton systems when it -40*F outside.
Geo in the ice is incredible. Love my Canada people.
Heat up there is a way bigger deal than southern Utah for sure
Why do you say geothermal instead of ground source?
That’s the terminology I’m used to in my area. ground source heat pump is definitely more correct though
@BatteryBuilds-p5x Do you use the term brine for the liquid in the ground loops even if it is water or glycol?
Almost always yes, glycol water mix 5-10% or at a minimum to allow loop temps to drop below freezing temperatures