Thank you for the detailed explanation. Good to know noise should not be an issue. I'm committed to climate-friendly technologies to the extent possible in our location, so I'm hoping that (financially) we can make geothermal work. We are going to try to include a solar array in our energy plan as well to try and offset some of our electric. The red flag I wondered about referred to the builder--like, if the builder is warning me about noise, maybe he's had a problem with his projects and he doesn't have a good contractor to install the system.

"Probably the best form of solar renewable energy per square foot available."

A good friend of mine built a good sized vacation house in a semi-remote area and equipped it with a ground source heat pump (that was VERY expensive) mostly because it was an area where the only "energy" utility available for his home is electricity. For the years since when he's owned the house, the largest source of electric power into this state's grid is from coal burning power plants. Coal is a major energy source producing electricity in many parts of the US.

How is this "solar renewable energy"?

I thought all energy was solar ... except geothermal.

Whether "ground source" is using some solar trapped heat vs geothermal sourced heat is beyond my knowledge. An article I found said that it depends where you are.

Certainly, in the summer it is purely using the ground insulation - ie neither solar or geothermal.

We’ve had GSHPs, one with the compressor in the attic and another located underneath the living space but not one in the conditioned space of the home. Noise was not an issue in either of these installations. When in the space with the compressor there is a low ”hum” but I never found this sound to be loud or offputting.

Our geothermal unit is very quiet. If it is in a utility room/hall with an access door closed it will be very hard to hear. The solar renewable energy part of geothermal is that it is using electricity to move heat, not create heat as in straight resistance heating. Nominally, for the amount of heat moved, about 1/3 of that heat is from the electrical equivalent powering the compressor and blower. So, 2/3 of the heat moved is 'free', coming from the ground or going into the ground.

"The solar renewable energy part of geothermal is that it is using electricity to move heat, not create heat as in straight resistance heating."

An air source heat pump works in an identical way.

As far as I know, the term "solar renewable" in current use refers to electricity produced either by photovoltaic panels (make electricity from sunlight) or solar thermal installations (power plants that use sunshine to produce heat to turn turbines). The original comment with that term in this thread is from someone known to stretch definitions and terms in a salesmanship, puffery way.

Ours are very quiet. the units are in the basement. we can’t hear them on the first floor at all.

We have a WaterFurnace 5 open-loop in the basement. Generally speaking, the air movement from the vents when the fan kicks to the higher speed (we have it on low-speed continuous), and the "popping" as the ducts expand/contract far exceed any noise from the compressor itself. But the newer units are well-insulated to minimize noise.

In our previous rental, it had forced-air gas, and the "kaboom" (well, I exaggerate a bit, but I never got accustomed to it) when it fired up was louder than the geo's compressor. ;-)

We *love* our geo (I had one for nearly 30 years previously too). Expensive up-front, but I wouldn't trade it.

Sounds like the hum the builder I spoke with referred to should only be noticeable when you're in the mechanical room. I wonder if he had an experience where pipes were not sufficiently isolated and brought vibrations up the wall from the unit? I would think the same thing could happen with other systems, other heat pumps, not just ground-source.

If you're accustomed to something like forced-air electric, where the only sound is the fan, then you may notice the compressor noise, but you'll get used to it very quickly.

Brad, that makes sense. What we will be happy to lose is the sound of the loud AC compressors when we're outside (and in some rooms inside as well).

It's true that if you're running a more eco-friendly system with electrical power that comes from a grid that's powered by coal, it's less eco-friendly, but it's better than running a non-eco-friendly system that's run off a grid powered by coal... Things are moving in the right direction as far as renewable energy in our area. Where we are building, the grid runs off a combination of sources that include a higher percentage of renewable energy sources than coal. But the majority of power comes from natural gas and nuclear energy. If we have a solar array, we should be able to offset some of our electrical need, but not all of it. We don't have access to natural gas, so whatever is not electric has to run off of propane, which, when you count delivery fees is more expensive. We'd like to keep that for emergencies, to run a generator. I realize the initial investment for GSHP is high, and that could present a problem, but I want to do everything i can to make the systems climate-friendly.

The coal argument is an evaporating one. Coal plants are being shut down for good regularly. They will not be replaced. At some point your system will not be powered by coal. Plus you have the option of using solar panels now to power it yourself. No coal involved. Used panels are less than $50/ea. for 195w.

I wasn't making an argument (not arguement), just describing what I'm sure was intentionally misleading wording used in an earlier comment by someone who does that regularly. It's my friend's system, not mine. He built the house a bit more than a dozen years ago and since then it's been essentially coal powered.

Here's an inconvenient truth that truth stretchers like to avoid. Keep in mind that natural gas and propane furnaces easily reach 95% plus efficiency. Meaning, 95% of the energy in the fuel translates into usable heat energy in the home. Natural gas fueled power plants are less than 50% efficient. Meaning, more than half the energy consumed is wasted before electricity is delivered to the user.

In cold weather areas, in the absence of natural gas, where the performance of ground source heat pumps can have an advantage over air source heat pumps, the lack of strong, direct sunshine on solar panels (because of rain, snow, clouds, the low position of the sun in the sky) pretty well makes the household reliant on the grid for electricity. Revert back to understanding what the power sources are while waving a phony ecology flag.

Step by step continuously up the mountain into the sunshine, as efficiencies increase and the cost of solar comes down along with batteries, more and more people can choose to forego fossil fuels and the real pollution they contribute. It's for most an economic decision first. But who prefers to pay more for fossil fuels so they can harm their environment?

“The original comment with that term in this thread is from someone known to stretch definitions and terms in a salesmanship, puffery way.”

That comment is from this site’s ‘Looney Tunes’ Troll and shoe salesman that follows me across this forum only to trash anything I post.

Just watch!

As a disinterested party, I have no monetary interest in anything the OP does and wish them the best of luck with whatever they choose.

I would however advise that if this is new construction, that they contract the HVAC, particularly if it’s geothermal, separately and hire their own professionals for both the source side geothermal and the distribution side, perhaps forced air ductwork or hydronic radiant or perhaps a combination of both, even including Domestic Hot Water (DHW). This might involve 2 or more specialized contractors.

Explore all subsidies, grants and tax credits available at all levels of government including utilities (for electrification), lenders and manufacturers. The more you require active space conditioning and hot water the more geothermal will make sense economically.

The geothermal industry is pressing hard and appears to be on the threshold of succeeding in achieving parity with the solar energy sector as it relates to Federal Tax Incentive Changes - in the US Congress. This is true for residential geothermal and even more so for commercial/institutional projects (above 300-tons) as well as utilities looking to sunset residential gas lines for geothermal.

IMPO (P = Personal and Professional)

SR

@2rickies, back to your question about noise, our first GSHP required a pressurized loop. It would sometimes lose pressure and suck in air. You could hear the air bubbles passing through the pipes when the system first came on. Maybe this is the pipe noise referenced.

Our current system, using the same loop, does not require pressurization so this is no longer an issue.

Hold the insults, bud. You peddle one solution whether it's what's most appropriate or not. You throw around popular buzz words whether they apply or not. I'm commenting about the repetitive song you sing and the shoe horn you use to make it fit, nothing about you personally. .

Funny thing, I've bought comprehensive HVAC systems for two different houses in the past 4 years and the excellent contractors I set up appointments with for a visit would not discuss recommendations until looking at the house and the installed equipment, taking measurements, and then having an in-depth discussion with me.

You, on the other hand, start pitching your one solution without knowing a thing about the who, what, where, when or why.

I'm coming back here to say I talked with a different builder who said a geothermal system was nice but its equipment would need to be replaced before we could "break even" on it. I am pretty sure this is not true. (But also i'm not doing it b/c of the break-even factor as much as b/c i don't want to be tied to fossil fuels for heating.) I know this builder prefers "dual-fuel" systems, electric where the propane kicks in when it gets very cold. I'm very aware that builders like to do what they're comfortable with, what they've done before, and what they have good subs for. (Even so, that builder's HVAC contractor has geothermal in his own home.) This builder also says he has never done radiant heat under wood floors. I know there are special requirements for doing radiant under wood, and maybe he hasn't had to deal with that, and would rather not. (Though I take his point that stone/tile will hold the heat better than wood.)

I just went to see a house-in-progress by the other builder, the one who warned about the hum. That (very large) house is being built with geothermal. That builder has geothermal in his own house. (He's also about to get a solar array at his house.) So between these two builders, at least I know which one is more geared toward climate-friendly systems.

Anyway, it's very easy to be lulled in these conversations and take the path of least resistance, i'm finding. When I'm listening to one builder, his explanation and solution sounds reasonable (eg the dual-fuel system, no radiant heat, no geothermal), even if it's not what I had as my original goal. And then I have another convo with someone else and get a different explanation, and tempting, finally, to go with the solution that fits what I want to hear.

If the money is not the primary deciding factor in this decision then go with the GSHP. IMO

Well it's certainly a factor! My bias is for renewables, and i would cut other things to be able to pay for it. Depends on where we are with the overall project once we get real budget numbers from builders.

Of course cost is a factor for most people. Where are you located?

I'm in climate zone 4.

Depending on your state's tax credits for geothermal, it may take an excessive amount of time for payback. We lost much of our state credit for geothermal, so it's less attractive now.

We did it again depsite the cost because, mostly, we didn't want the noise of the outdoor units disturbing our peace in the country. The units we chose are variable speed blowers, compressors and pumps, which should make them very efficient at low loads. We're also making domestic hot water with the heat pump The key to doing all this is having the right HVAC contractor.

As for longevity - I expect decent life of the equipment with nothing outside exposed to weather. Additionally, a lot of the cost is in the loop and the ducting, which would be used again with replacement equipment. And - the ENTIRE installation is eligible for the credit - loops, equipment and ducting (with labor) so that ends up being a good deal in the federal tax credit.

I don't think our existing geothermal is all that efficient, frankly, but I enjoy not dealing with the outdoor units. I expect the new installation to be better based on the improved equipment.