# Ask the guy who had a geothermal HVAC system installed **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 18, 2013, 9:09pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298 "2013-03-18T21:09:19Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![StGermain](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stgermain/32/2868_2.png) [@StGermain](https://boards.straightdope.com/u/StGermain)\ **Post date:** [March 20, 2013, 8:16pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/21 "2013-03-20T20:16:25Z")
Since installing central heat and air is in my plan in about 5 years, I’m interested in this. I have plenty of land, but hit limestone about 10" down (They call Tennessee Rocky Top for a reason). I have a water well, but I don’t know how deep it is. I don’t have any duct work in my 160+ year old house, and currently hear with a pellet stove and cool with a window A/C in my bedroom. I’ll need to upgrade my electrical before I do anything toward a central system. If I’m starting from scratch, would this be reasonable in cost? StG ---
**Author:** ![NBYodo](https://avatars.discourse-cdn.com/v4/letter/n/a9a28c/32.png) [@NBYodo](https://boards.straightdope.com/u/NBYodo)\ **Post date:** [March 20, 2013, 8:50pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/22 "2013-03-20T20:50:09Z")
Very cool undertaking. It is a pipe dream of mine to have such a system if I ever get a house where it is suitable and still can afford it. Do you find the new indoor unit much noisier than your old furnace, given the compressor is now inside? Re depth of wells, I would imagine that the constant temperature depth would vary somewhat on local conditions. NB ---
**Author:** ![corkboard](https://avatars.discourse-cdn.com/v4/letter/c/e9bcb4/32.png) [@corkboard](https://boards.straightdope.com/u/corkboard)\ **Post date:** [March 20, 2013, 10:01pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/23 "2013-03-20T22:01:13Z")
> [@Hari\_Seldon](#): > > I want to make the point that this is **not** geothermal heating or cooling (although it is often described that way). What it is a heat pump that pumps heat up during the winter and down during the summer. True geothermal heating would require going down thousands of feet at least. At least in most places (including New Jersey). > > That said, it is much more efficient than any other form of heating or cooling. I have contemplated it, but right now the price is not right. I imagine that after the providers have enough experience, prices will fall. That may be true, but everyone we spoke to and just about everything I read during our research phase referred to this process as geothermal heating and cooling. So, there’s that. > [@hogarth](#): > > Do you have any guesses how much maintenance will cost? What happens if something breaks – do you have to dig up the whole yard again? Much the same as with any other HVAC, and possibly less. Every six months we’re supposed to replace the filter, which you can get at Home Depot or Lowes. We had a year of free service from the company that installed it, and on their two visits they came out, looked at the gauges, replaced the filter, and left. So now I do it myself. Maybe in five or ten years I’ll pay to have them come out for a full inspection again. > [@FoieGrasIsEvil](#): > > Have you been through a really hot Summer with that system yet? I ask because my brother and SIL had one of these put into their new home a couple years ago and every time I have been over to their place on a really hot day it just doesn’t really feel like the unit is doing a very good job of removing the humidity from the air inside the house. They would set their thermostat to like 72 degrees and the system didn’t ever seem to be able to get the temperature below 74. > > Also: is there a sight gauge or something whereby you can monitor your antifreeze level? If you have some ground shift and one of your PVC pipes cracks or breaks, is the only way to repair that to pull up the piping and replace it all? How could anyone tell where the leak would even be given the depth of the piping and the fact that it’s encased in concrete? We had it for the summers of 2011 and 2012, which I guess were about average in our area. There were days in the upper 90’s and maybe one or to over 100, but inside the house it was as comfortable as any other day of the year. There are two pressure dials on the pipe in the basement where it enters and exits the foundation wall. They measure the pressure of the fluid in the pipe, and they’re supposed to be 10 (I think) pounds off of each other. Every now and then when I’m down there I glance at them but I don’t have to do anything special. There’s also a digital display that shows us the temp of the fluid as it’s leaving the unit; temp as it returns from underground; temp of the air that’s being sent through the ducts; temp of the air when it returns to the furnace; and two other things, I forget. It’s really there for the techs who come out for service or if there’s a problem. > [@bup](#): > > The [wikipedia article](http://en.wikipedia.org/wiki/Geothermal_heat_pump) on this topic says it’s only about 20 feet. But whatever. I guess the engineers still figured 450 feet twice was cheaper than 165 feet 6 times. Twenty, fifty, whatever. Most of the people we spoke to, including the guys running the drilling rig, gave a depth in the 40-50 foot range. > [@StGermain](#): > > Since installing central heat and air is in my plan in about 5 years, I’m interested in this. I have plenty of land, but hit limestone about 10" down (They call Tennessee Rocky Top for a reason). I have a water well, but I don’t know how deep it is. > > I don’t have any duct work in my 160+ year old house, and currently hear with a pellet stove and cool with a window A/C in my bedroom. I’ll need to upgrade my electrical before I do anything toward a central system. If I’m starting from scratch, would this be reasonable in cost? > > StG That will certainly add years to your break-even point. There are many factors involved in making that calculation, including the size of your house and how well insulated it is. If it’s 160+ years old, it might not be insulated at all. It’s hard, or impossible, really, to determine what the break-even point is ahead of time, because you need to have it operating for at least a year to compare your monthly cost to the pre-geo days over the course of a full year to determine your savings. We aren’t saving as much as they predicted, but close. On the other hand, you may decide it’s right for you even if it ends up costing more in the long run than a traditional system, because it uses so much less fossil fuel than a traditional system. So you may decide it’s the right thing to do even if it’s not the most fiscally prudent way to go. > [@NBYodo](#): > > Very cool undertaking. It is a pipe dream of mine to have such a system if I ever get a house where it is suitable and still can afford it. > > Do you find the new indoor unit much noisier than your old furnace, given the compressor is now inside? > > Re depth of wells, I would imagine that the constant temperature depth would vary somewhat on local conditions. > > NB Only slightly noisier, but not because of the compressor. The compression coil is inside the furnace, and it’s nowhere near the size of a traditional A/C compressor that sits outside the house. If you were to look at the furnace in my basement and you didn’t know anything about the geothermal system, you wouldn’t think it’s any different than a regular furnace. The only way it’s noisier is I think the blower is stronger than the old unit, so it sounds as if the air is louder coming out of the register. If that makes any sense. And it’s only when we’re sitting in the room that’s right over the unit in the basement, which is the first room in the duct line. ---
**Author:** ![cougar58](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@cougar58](https://boards.straightdope.com/u/cougar58)\ **Post date:** [March 21, 2013, 1:56am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/24 "2013-03-21T01:56:33Z")
why couldn’t they make it an under the floor heat system, like I have with a huge propane hot water tank that circulates water under the floor (garage floor optionally as well) to heat the house? It sounds like it has hot fluid in the pipes…so why use a dusty blower, which forces hot air to the ceiling, to get warm air at eye level? The AC of course still uses the blower vents, as do a backup heat system (propane gas). I am guessing the fluid is warm, and not hot, and circulates constantly? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [March 21, 2013, 2:41am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/25 "2013-03-21T02:41:53Z")
for floors to heat a room they run at about 100F. ground heat is much lower temp, heat has to be pumped out of it. ---
**Author:** ![sinjin](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@sinjin](https://boards.straightdope.com/u/sinjin)\ **Post date:** [March 21, 2013, 2:45am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/26 "2013-03-21T02:45:23Z")
> [@FoieGrasIsEvil](#): > > Have you been through a really hot Summer with that system yet? I ask because my brother and SIL had one of these put into their new home a couple years ago and every time I have been over to their place on a really hot day it just doesn’t really feel like the unit is doing a very good job of removing the humidity from the air inside the house. They would set their thermostat to like 72 degrees and the system didn’t ever seem to be able to get the temperature below 74. > > Also: is there a sight gauge or something whereby you can monitor your antifreeze level? If you have some ground shift and one of your PVC pipes cracks or breaks, is the only way to repair that to pull up the piping and replace it all? How could anyone tell where the leak would even be given the depth of the piping and the fact that it’s encased in concrete? I think something is wrong with you brother’s system. We had a ground source heat pump (the same as some people call geothermal) for 12 years in the St. Louis area. It was hell hot there and we kept our house at \<70 at all times. My neighbors joked that our toilet seats were cold in August. We had our system serviced every year and based on the fluid pressure the techs were able to adjust the system as needed for no additional charge. Our average electric bill, we were all electric, for a 3300 sq ft house and a hot tub was $150/mo. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 21, 2013, 2:57am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/27 "2013-03-21T02:57:35Z")
How hot was it outside when you kept it \< 70? 🙂 ---
**Author:** ![sinjin](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@sinjin](https://boards.straightdope.com/u/sinjin)\ **Post date:** [March 21, 2013, 3:03am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/28 "2013-03-21T03:03:15Z")
> [@carnivorousplant](#): > > How hot was it outside when you kept it \< 70? > 🙂 Well temps in St Louis in the summer seem to hover in the upper 90’s for weeks on end so there you go. \ Highs in the upper 90’s, humidity 95%, chance of afternoon thunderstorms, possibly severe\ ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 21, 2013, 3:10am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/29 "2013-03-21T03:10:14Z")
Wow. I thought you guys were Yankees. 🙂 ---
**Author:** ![sinjin](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@sinjin](https://boards.straightdope.com/u/sinjin)\ **Post date:** [March 21, 2013, 3:17am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/30 "2013-03-21T03:17:27Z")
> [@carnivorousplant](#): > > Wow. > I thought you guys were Yankees. > > 🙂 Well we do eat apple pie for breakfast with a knife, but only occasionally with cheese.🆒 But we did live in Schenectady for years. ---
**Author:** ![corkboard](https://avatars.discourse-cdn.com/v4/letter/c/e9bcb4/32.png) [@corkboard](https://boards.straightdope.com/u/corkboard)\ **Post date:** [March 21, 2013, 2:48pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/31 "2013-03-21T14:48:55Z")
> [@cougar58](#): > > why couldn’t they make it an under the floor heat system, like I have with a huge propane hot water tank that circulates water under the floor (garage floor optionally as well) to heat the house? > > It sounds like it has hot fluid in the pipes…so why use a dusty blower, which forces hot air to the ceiling, to get warm air at eye level? > > The AC of course still uses the blower vents, as do a backup heat system (propane gas). > > I am guessing the fluid is warm, and not hot, and circulates constantly? Because we didn’t want to install a radiant heat system throughout the house. That would have required either pulling up the floor or opening the ceiling in every room. Plus, part of our house sits on a concrete slab, and I wasn’t about to start jackhammering that up. I forget what temp the fluid is, but the air that gets pushed through the ducts starts out in the 90’s in the winter. And it’s not dusty. We replace the filter regularly and it catches everything on the return trip. In a properly designed forced air system, the registers are near or in the floor and the returns are near the ceiling. The idea is that the air enters the room low and exits high, thereby circulating the conditioned air through the room. It’s quite comfortable. ---
**Author:** ![Snickers](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Snickers](https://boards.straightdope.com/u/Snickers)\ **Post date:** [March 21, 2013, 7:15pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/32 "2013-03-21T19:15:09Z")
Holy cats, $400 a month? My house was built in 1931, leaks like a sieve around the windows and doors, and my highest bills were half that. In _January_. Now that I replaced our old roof with a metal roof (which involved some blown insulation in some dead spaces and in the attic), I pay about $100, $120 (at most) a month for heating. Thought they’d build 'em better in Jersey. 🙂 Nice setup, though. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [March 21, 2013, 7:25pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/33 "2013-03-21T19:25:39Z")
> [@Snickers](#): > > Holy cats, $400 a month? My house was built in 1931, leaks like a sieve around the windows and doors, and my highest bills were half that. In _January_. That is remarkable for MN. What do you heat with? How large is your house? ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [March 25, 2013, 1:26am UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/34 "2013-03-25T01:26:34Z")
There was an episode of _This Old House_ about a week or two ago where they had installed a rather complicated looking geothermal system. IIRC, they split it out to do radiant (in-floor) heating, standard ducted air conditioning and domestic hot water. Their basement looks like a dairy with multiple runs of pipe, valves and gauges everywhere, but from your description, you system looks fairly normal? ---
**Author:** ![corkboard](https://avatars.discourse-cdn.com/v4/letter/c/e9bcb4/32.png) [@corkboard](https://boards.straightdope.com/u/corkboard)\ **Post date:** [March 25, 2013, 1:38pm UTC](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298/35 "2013-03-25T13:38:26Z")
> [@gotpasswords](#): > > There was an episode of _This Old House_ about a week or two ago where they had installed a rather complicated looking geothermal system. IIRC, they split it out to do radiant (in-floor) heating, standard ducted air conditioning and domestic hot water. Their basement looks like a dairy with multiple runs of pipe, valves and gauges everywhere, but from your description, you system looks fairly normal? Right. Radiant floor heating, from what I understand, involves a hot water distribution system with pipes or PEX tubing running to various places in the home off of a manifold that evenly distributes the water throughout the system. We don’t have that. [Previous page](https://boards.straightdope.com/t/ask-the-guy-who-had-a-geothermal-hvac-system-installed/653298.md?page=1)