geothermal heatpump HVAC

[masraum]

Anyone got geothermal? It seems like a very efficient way to go, although I understand it takes far more space than most folks have.

What do you know? What are your thoughts?

If anyone has it, was yours a retrofit or new build, and do you know how the initial cost compared to non-geothermal installation?

[LWJ]

I have some clients that do this work. It is costly on the front end. Very cheap to run. It does take some real estate for a ground loop. I know a leading manufacturer is waterfurnace. Might start there and see what info you can obtain. If I were starting from scratch, I would absolutely look into this.

[masraum]

I've seen things that say that the initial cost is about 1.5x the cost of traditional HVAC. I'm not sure if that's for new build or retrofit. We'd like to go this route and I think we've got ample space, but I'm not sure that it's going to be cost effective, even if we understand and are willing to pay more upfront. I'm curious how much that "pay more" is going to be and what other changes will be required.

[rockfan4]

I have a Waterfurnace system.
Installed 9 1/2 years ago, new build.
The ductwork is much larger than with a conventional forced air system, and the output air isn't that warm compared to a gas furnace. I think my system has been running continuously for a few days now, we're in a cold snap.

External, I have three vertical wells for heat transfer, they're about 10 feet apart and 200 feet deep.

Running cost is very reasonable.

One benefit that you don't realize is the lack of noise outside. The neighbor's outside AC is loud as hell when it is running, my house is silent.

Two failures since I've owned it. First was an install error, there was a leak in the ground loop letting air into the system, took them a couple months to find it.
Second failure was last year, the soft-start module on the compressor motor failed. Covered under the 10 year parts warranty, I paid the trip charge.

Keep your filter clean. I have an AprilAire MERV 13 that is supposed to last a year, but doesn't. I blame the dogs. When it gets dirty I hear a "thump" from the air duct when the fan kicks on, and then I know I have about a month before I need to change it.

One other issue related to the install. The system has trouble lights, but they're on the system itself and there's no error shown on the Honeywell thermostat they installed with the system. The first time the ground loop leak shut down the system I didn't know until I got a huge electric bill. Electric resistance backup heat.
I had them come out to install a different, Waterfurnace thermostat, the guy worked on it a couple hours, and gave up.
I ended up "reading the manual" (crazy concept, I know), and ordered a different Honeywell thermostat and installed it myself.

Edit: Cost to install. I don't know, I don't want to know. Since it was a new house the ductwork counted as part of the install so it was included in the energy rebate on my taxes. If you're retrofitting a existing house you may need to change your ductwork.

[biosurfer1]

I work for an electric utility and worked on a ground source geothermal HVAC system at a customer site. We typically pay a customer to monitor an installation they are already doing in these types of projects.

The one I followed along with was installed about 7-8 years ago.

Overall, it was a decent project that was cheap to run, but seemed to be plagued with issues from the first commissioning. There were leaks in the loop, it had to be converted from a pressurized flow center to non-pressurize, and the unit would trip off during very hot or cold spells.

It could have been that it was a somewhat new technology for residential or the installer wasn't as versed but I dont think the customer would have done it again.

FYI, this project was about 2.5-3x what a comparable heat pump HVAC system would have cost (this project was retrofit), plus there was ~$3250 in fixes needed after a year to fix the issues.

[masraum]

Originally Posted by rockfan4

I have a Waterfurnace system.
Installed 9 1/2 years ago, new build.
The ductwork is much larger than with a conventional forced air system, and the output air isn't that warm compared to a gas furnace. I think my system has been running continuously for a few days now, we're in a cold snap.

External, I have three vertical wells for heat transfer, they're about 10 feet apart and 200 feet deep.

Running cost is very reasonable.

One benefit that you don't realize is the lack of noise outside. The neighbor's outside AC is loud as hell when it is running, my house is silent.

Two failures since I've owned it. First was an install error, there was a leak in the ground loop letting air into the system, took them a couple months to find it.
Second failure was last year, the soft-start module on the compressor motor failed. Covered under the 10 year parts warranty, I paid the trip charge.

Keep your filter clean. I have an AprilAire MERV 13 that is supposed to last a year, but doesn't. I blame the dogs. When it gets dirty I hear a "thump" from the air duct when the fan kicks on, and then I know I have about a month before I need to change it.

One other issue related to the install. The system has trouble lights, but they're on the system itself and there's no error shown on the Honeywell thermostat they installed with the system. The first time the ground loop leak shut down the system I didn't know until I got a huge electric bill. Electric resistance backup heat.
I had them come out to install a different, Waterfurnace thermostat, the guy worked on it a couple hours, and gave up.
I ended up "reading the manual" (crazy concept, I know), and ordered a different Honeywell thermostat and installed it myself.

Edit: Cost to install. I don't know, I don't want to know. Since it was a new house the ductwork counted as part of the install so it was included in the energy rebate on my taxes. If you're retrofitting a existing house you may need to change your ductwork.

Thanks, lots of good info. I'd seen something online about changing the ducts. I don't understand why, but I'm sure there's a reason. That could be an issue because our current setup uses round flexible ducts and there's not a lot of room to make big changes.

Of course, it makes sense that there'd have to be some sort of backup heat. I wouldn't think that you'd ever need it unless there was a failure (like you experienced).

[TheMentat]

My dad installed them on a couple of high-end spec builds about 10-15 years ago. He bought the lot with the wells already there, so he gave it a whirl. I get the impression that there were a lot of issues, but I suspect (hope?) things have improved since then.

[rockfan4]

The reason for the larger ducts is because the air coming out of the system isn't that much warmer or colder than the return air, so you have to move a lot more air to heat or cool a room. I went downstairs and the return duct to the system is 20x22, so a little larger than most systems that are 16x20 or 16x25.

The run to each room is a 6" round duct, a 10x12 room has one run, the master has two runs.

The emergency heat is supposed to kick in when it is too cold for the system to heat the house, geo shuts down and it goes to straight resistance heat. My system was designed to cut over around 2 - 4 degrees, but my ground loop is much more efficient than what they estimated, and even at -10, -15 overnight I don't think it has cut over. I can usually tell when it goes to resistance heat, even with the MERV 13 filter there's a little dust on the coils and you can smell when they heat up.

[masraum]

Originally Posted by biosurfer1

I work for an electric utility and worked on a ground source geothermal HVAC system at a customer site. We typically pay a customer to monitor an installation they are already doing in these types of projects.

The one I followed along with was installed about 7-8 years ago.

Overall, it was a decent project that was cheap to run, but seemed to be plagued with issues from the first commissioning. There were leaks in the loop, it had to be converted from a pressurized flow center to non-pressurize, and the unit would trip off during very hot or cold spells.

It could have been that it was a somewhat new technology for residential or the installer wasn't as versed but I dont think the customer would have done it again.

FYI, this project was about 2.5-3x what a comparable heat pump HVAC system would have cost (this project was retrofit), plus there was ~$3250 in fixes needed after a year to fix the issues.

Lots of good info, thanks. Good to know. I'd say this puts it out of the running for us for a retrofit "2.5-3x what a comparable heat pump HVAC system would have cost (this project was retrofit)" We aren't sure that we're going to be there forever.

I posted the question on a facebook group in the area of our property, and I got two immediate responses to which I felt that I had to respond with "are you talking about a regular heat pump or a geothermal heat pump." One person immediately responded with "I don't know, what's the difference?" I suspect the other is doing an imitation of a deer in headlights.

[masraum]

Originally Posted by rockfan4

The reason for the larger ducts is because the air coming out of the system isn't that much warmer or colder than the return air, so you have to move a lot more air to heat or cool a room. I went downstairs and the return duct to the system is 20x22, so a little larger than most systems that are 16x20 or 16x25.

The run to each room is a 6" round duct, a 10x12 room has one run, the master has two runs.

Ah, ok, that's not bad or crazy. The runs to our rooms are probably 6" round or larger. Because of where our indoor unit is the return is going directly into the front of the indoor unit and is 24x24" so the duct work may not be an issue. Thanks

[flipper35]

Ours was a retro fit and cost quite a bit more than a standard install because there was an addition to the house and the duct work was too small for the existing furnace and most had to be replaced. Luckily it is all above the drop ceiling in the basement.

That said, it paid for itself over the oil heat in 6.5 years. It blows air temps about 90* at the registers but without combustion it does not dry the air like oil or gas furnaces.

We also had to have the loop horizontally bored because of trees and the septic system even though we have nearly 1.5 acres. That was OK since we didn't have to fix the landscaping and worth the extra $1500 it cost to do it that way.

It is a very quiet system, especially in the summer since there is no compressor outside. It has electrical emergency heat if it gets too cold, but it has not yet used it even though it was -22 Sunday, though it was finally running the fan at full speed. We did blow in extra insulation in the attic and the house is only 2400 sq/ft with brick exterior if that helps. Were I to build a new house I would do it again, maybe even with heat in the floor.

Oh, they estimated our Wisconsin summers would cost about $32 per year in cooling costs. Our old A/C unit, before the lightning strike, was 3x that per month i the summer time and we get 4x more heat per kw than direct electrical heating. It also puts waste heat in our water heater in the summer and winter so the water heater never runs if the pump is running. It has a safety cutoff so it never gets above 131* at the faucet.

You do have to keep the filter clean, but they are washable. We have a spare paper fiber filter to put in for a day while the regular one dries.

Ours was installed in 2009 and the only issues were a leak in the basement where the loop came in, which they fixed promptly and a control board went out last year. They do service it every few years to check for air and coolant levels at no charge for us. Hope that helps out.

[flipper35]

Originally Posted by masraum

Ah, ok, that's not bad or crazy. The runs to our rooms are probably 6" round or larger. Because of where our indoor unit is the return is going directly into the front of the indoor unit and is 24x24" so the duct work may not be an issue. Thanks

In TX you may not need the largest duct work if it doesn't get as cold as here. I would have someone reputable check it out.

Even with the extra expense ours saved enough to pay for itself in short order.

[cabmandone]

Big thing is, find out what type of loop they typically use in your area. You want one that will get the most heat extraction the fastest. Back when I was installing them, most were horizontal ground loops where they'd dig and bury the loop. The problem we saw with that was, until the ground settled you don't get full heat extraction.

Up front cost is significantly more simply because of the loop cost, electrical supply to the unit if you're using electric resistance as backup and in part due to piping the system in. A nice benefit is... "free" hot water. If you install a geothermal make sure you get the option for heating water. I'd think in your climate that a geothermal system would be optimal.

From what I recall, duct sizing isn't any different than sizing for a typical air to air heat pump.

[flipper35]

Originally Posted by cabmando

Big thing is, find out what type of loop they typically use in your area. You want one that will get the most heat extraction the fastest. Back when I was installing them, most were horizontal ground loops where they'd dig and bury the loop. The problem we saw with that was, until the ground settled you don't get full heat extraction.

Up front cost is significantly more simply because of the loop cost, electrical supply to the unit if you're using electric resistance as backup and in part due to piping the system in. A nice benefit is... "free" hot water. If you install a geothermal make sure you get the option for heating water. I'd think in your climate that a geothermal system would be optimal.

I forgot about that. We had to have the service upgraded to the house. Still cheapest way to go in the long run.

[cabmandone]

Originally Posted by flipper35

I forgot about that. We had to have the service upgraded to the house. Still cheapest way to go in the long run.

You can get a system with gas or propane backup. Naturally, you pay one way or the other. Either you increase your electric service or you pay additional for the gas heat and line installation if you have no gas service to the home.

[flatbutt]

I've never understood how so much heat can be extracted from ground wells that are only a few hundred feet deep.

[masraum]

Originally Posted by flipper35

Ours was a retro fit and cost quite a bit more than a standard install because there was an addition to the house and the duct work was too small for the existing furnace and most had to be replaced. Luckily it is all above the drop ceiling in the basement.

That said, it paid for itself over the oil heat in 6.5 years. It blows air temps about 90* at the registers but without combustion it does not dry the air like oil or gas furnaces.

We also had to have the loop horizontally bored because of trees and the septic system even though we have nearly 1.5 acres. That was OK since we didn't have to fix the landscaping and worth the extra $1500 it cost to do it that way.

It is a very quiet system, especially in the summer since there is no compressor outside. It has electrical emergency heat if it gets too cold, but it has not yet used it even though it was -22 Sunday, though it was finally running the fan at full speed. We did blow in extra insulation in the attic and the house is only 2400 sq/ft with brick exterior if that helps. Were I to build a new house I would do it again, maybe even with heat in the floor.

Oh, they estimated our Wisconsin summers would cost about $32 per year in cooling costs. Our old A/C unit, before the lightning strike, was 3x that per month i the summer time and we get 4x more heat per kw than direct electrical heating. It also puts waste heat in our water heater in the summer and winter so the water heater never runs if the pump is running. It has a safety cutoff so it never gets above 131* at the faucet.

You do have to keep the filter clean, but they are washable. We have a spare paper fiber filter to put in for a day while the regular one dries.

Ours was installed in 2009 and the only issues were a leak in the basement where the loop came in, which they fixed promptly and a control board went out last year. They do service it every few years to check for air and coolant levels at no charge for us. Hope that helps out.

That sounds like a really positive experience, which is nice to see/hear for a change.

I had to giggle when I read "summers would cost about $32 per year in cooling costs. Our old A/C unit, before the lightning strike, was 3x that per month i the summer," but of course, your summer and ours is are a little different.

[masraum]

Originally Posted by cabmando

You can get a system with gas or propane backup. Naturally, you pay one way or the other. Either you increase your electric service or you pay additional for the gas heat and line installation if you have no gas service to the home.

Our current system is a heat pump with electric emergency and aux heat that was all installed in 1991. I would hope the fact that we already have electric emergency/aux heat would mean that we wouldn't need to increase our electric service. The house is also 96 years old with not a lot of insulation. (I'll be posting a thread about installation upgrades eventually I'm sure, I'm wondering maybe spray foam)

[masraum]

Originally Posted by flatbutt

I've never understood how so much heat can be extracted from ground wells that are only a few hundred feet deep.

Our air to air heat pump works reasonably well down to 35-40º. If the ground stays in the 55-60º range, that's a big difference, and as long as you don't live inside the arctic circle or Siberia with permafrost, it probably doesn't take much depth to reach a decent temp. And if you're thinking "but the ground gets cold (frozen in the north) up at the top, but that doesn't last long as you work your way down. There's a lot of "ground" and it's all connected, so the heat tries to reach equilibrium constantly.

[cabmandone]

Originally Posted by masraum

Our current system is a heat pump with electric emergency and aux heat that was all installed in 1991. I would hope the fact that we already have electric emergency/aux heat would mean that we wouldn't need to increase our electric service. The house is also 96 years old with not a lot of insulation. (I'll be posting a thread about installation upgrades eventually I'm sure, I'm wondering maybe spray foam)

That's right! I forgot what system you have. You should be good since the electric resistance should be similarly sized. My .02, I'd put money in insulating the home and getting it as tight as you can before I did much with the heating system. The heating system is only as efficient as the home allows it to be.

I think I mentioned this before but, I'd HIGHLY recommend you have a full energy audit done. This will help you focus your spending on the areas where it will be the most benefit. I had an energy audit done last year and it really helped me focus on where my sources of energy loss existed.