The geothermal discussion thread

[apostolakisl]

I think you should be more proactive and not just prevent it or detect it, but prevent it happening again. Just mount a hand grenade under the unit, and wire the pin to a bolt in the cement base. Its doubtful anyone stealing it the first time will ever do it again.

Also, is the theft of HVAC a problem in your area? If it is, maybe just a camera and video recorder is the best solution. Then if its stolen, they will put the video on the local news, and I bet if won't be missing long after that.

Probably just a camera mounted up high out of the way with a sign on the unit saying "smile, your on my IP camera broadcasting live around the world" and an arrow pointing up to the camera might just convince most would be thieves to mozy on their way. Even if the camera were fake.

Also regarding the geotherm thing, I was super interested in doing that for my new house but it really doesn't pay off, at least not where I live having to drill the holes. I got a top of the line SEER 19 carrier infinity two stage with all the bells and whistles for $30k (8 ton). The geotherm was $80k for one bid (8 ton) and $60k (6 ton) from a different contractor. The 6 ton guy was the only one who believed that would be enough. I have lived in the house 15 months. It is an all electric heat pump house. My worst bill was $400 and that was August when it was over 100 every day. My total anual electricity for the year was about $3k. Let's say $2k was the heat pump. If the geo therm was 50% more efficient (which it isn't) then it would save $1k per year. Even if it saved $2k per year, that is a bad way to invest $50k. I think geotherm is probably great if you have a lake to dump the heat into or a really shallow water table where you can pump water up to heat/cool the coils.

 

[beelzerob]

I don't think theft in general is a problem in the area. Some of the others that live nearby had burglary attempts, but nothing recently or repeatedly. It seemed to be more of a drive by smash and grab type of thing to me.

Matt

Ya, crime like that is why I moved to PA!

*Notices mdonovan's location*

Oh....nevermind.

Lou, I don't think geothermal scales up well at all because of...well, the wells. Going open loop, with only a single return well and including a pump upgrade to give me enough water, is still about $6k less than a similar closed loop system with vertical wells, and I'm only a 4-ton system. Each ton is another well in a closed loop system, and so the bigger the system, the much more expensive it is. I guess geothermal is best suited to smaller applications.

Our bills in winter were approaching $300, and the house was still not satisfactorily warm to me. And prices become unhinged in PA this year, so that's sure to go up. But I'm not even really thinking payoff...I'm just wanting better heat, and also a big boost in our hot water capacity (we spend a lot of time in our walk-in shower), and in about 20-25 years when the kids are all gone, hopefully it'll boost the selling price. But *shrug* we're here for life, so payoff doesn't really matter to me.

Of course, the current tax rebate of 30% (and propsed rebate of 50%) also make a huge difference in being able to do this now.

 

[Ira]

For geo-thermal wells, what is considered a "shallow water table". Around here, there is a massive water table at about 120 feet. Is that shallow enough to make an open loop system reasonably priced?

Also, if water from a small lake is being used, how detrimental is it to the lake? We hope to build a home on property we own that is on a 75 acre private "lake" that averages about ten feet deep. The lake is actually an ancient oxbow bend of a nearby river. There are about 60 homes on the lake, each with about 300' of water frontage. A handful of the homes use the water for drinking and/or sprinkler systems. Is the amount of heat extracted from or released into the water minor enough to not matter?

Ira

 

[apostolakisl]

For geo-thermal wells, what is considered a "shallow water table". Around here, there is a massive water table at about 120 feet. Is that shallow enough to make an open loop system reasonably priced?

Also, if water from a small lake is being used, how detrimental is it to the lake? We hope to build a home on property we own that is on a 75 acre private "lake" that averages about ten feet deep. The lake is actually an ancient oxbow bend of a nearby river. There are about 60 homes on the lake, each with about 300' of water frontage. A handful of the homes use the water for drinking and/or sprinkler systems. Is the amount of heat extracted from or released into the water minor enough to not matter?

Ira

Ira, that 75 acre lake sounds like a geotherm dream to me. Unless the temps at the bottom of the lake go to severe it would be a great heat sink and easy to tap into.

120 foot water table is I think kind of deep for open loop. Remember you have to pump the water up 120 feet which is totally wasted energy. It will depend on the temp of the water of course. If your ground water is like 55 degrees it would work great for both heating and cooling and require lower volumes. You also need somewhere to dump the water.

Where I live the water is 700 ft down there. I have a well for irrigation but no where to dump the water without ticking people off. I suppose I could just water the lawn a bunch. The temp of water down there is about 70. The gound is limestone with only 1 inch of dirt. The geotherm bids I got all said I needed closed loop. I was concerned about saturating the holes with heat toward the end of our 9 month cooling season and 100 plus degree days.

I will say that doing the open cell spray in foam is a total no brainer. I put that stuff in and it works awesome. I have more than 6000sf with 12 foot ceilings and 10c/kwh e and still my bills are pretty good (about the same as my old piece of junk 2500sf house). For sure get the foam! Also have the house envelope insulated. In other words, the undersurface of the roof is insulated, not the ceiling of the second floor. My attic only gets up to 85 degrees on a 105 sunny day even though there are no ducts up there.

 

[beelzerob]

A small comment about geothermal heating has threatened to overtake a poor innocent thread, so I thought I'd start a place where those discussions could call home.

I'm in the middle of getting bids for a geothermal system for our house, as I discuss in my cocoontech blog, but I'm by no means an authority. But I'll be happy to answer any questions on there. For general overview of what we're talking about, the geothermal heat pump wiki is not a bad place to start.

In answering one particular comment, I want to discuss using a pond for geothermal heating/cooling. It is a very good and very cheap way to implement a closed loop system. I say that to emphasize that you use the pond the same way you would buried pipes (they're just buried in water!), not as a source for your open loop needs. I'd guess the main reason for this is because of how dirty the water is sure to be, and that makes it not a good candidate for running through your very expensive furnace!

Ponds do, however, make a very good spot to dump your open loop water. Most ponds of a decent size can easily absorb that much water...but really you'd be better off using it as a closed loop heat source/sink.

 

[apostolakisl]

An small comment about geothermal heating has threatened to overtake a poor innocent thread, so I thought I'd start a place where those discussions could call home.

I'm in the middle of getting bids for a geothermal system for our house, as I discuss in my cocoontech blog?, but I'm by no means an authority. But I'll be happy to answer any questions on there. For general overview of what we're talking about, the geothermal heat pump wiki is not a bad place to start.

In answering one particular comment, I want to discuss using a pond for geothermal heating/cooling. It is a very good and very cheap way to implement a closed loop system. I say that to emphasize that you use the pond the same way you would buried pipes (they're just buried in water!), not as a source for your open loop needs. I'd guess the main reason for this is because of how dirty the water is sure to be, and that makes it not a good candidate for running through your very expensive furnace!

Ponds do, however, make a very good spot to dump your open loop water. Most ponds of a decent size can easily absorb that much water...but really you'd be better off using it as a closed loop heat source/sink.

Sorry about hijacking the other thread. I would move my post but don't know how to do that.

For the lakes they drop a plate with pipes snaking through it to heat transfer the closed loop water into the lake, beelzerob is right on that. I know people here in Austin that live on lake Travis and have done that. The surface temp there gets over 90 in the summer so it really only works well where people have deep water access. Becuase close loop systems balance the weight of lifting the water with the weight of the down flowing water, there is no energy lost to lifting, only to flow resisance from the pipe which is pretty minor unless the pipe is very thin or very long.

I was really excited about doing geotherm on my new house but just couldn't make it work on my land. The SEER 19 carrier unit I got instead, however, is really nice. It is really quiet and very efficient.

 

[beelzerob]

Whereabouts do you live, Lou? Air exchange heat pumps are great in moderate climates, it's in the more extreme places they don't do so well. SEER19 is pretty significant. We have a 13 SEER, and it was probably sufficient...just not *comfortable* in the depth of winter.

But for the size of house you mentioned, I'm not surprised at all that geothermal is not attractive. My neighbor got an estimate for geothermal about the same time we did. Ours came out at around $20k (this was last year), his was like $50k. But he had a much larger house than us, *AND* wanted to heat his pool and garage! That came to around a 7 ton system, which meant 7 closed loop wells....that's what made the price difference.

It seems like most contractors I talk to really push the closed loop systems, though they're the most expensive (vertical loops that is...horizontal is the cheapest). I guess water quantity and quality really is that elusive, in which case we've really lucked out.

I do realize I'll be spending extra electricity just to pump the water up. Our current pump (which will have to be replaced) uses about 1800 watts to give 8gpm steady, which is what a full-out 4 ton unit would use. So, that's close to 2kWh an hour, at around $.09/kWh that begins to add up. But its nothing compared to what our water heater uses when it's going, and if the water preheating feature of the geothermal unit is at ALL what it claims to be, then it will more than even out.

Again though...I'm just looking for better heat. I think Id be happy paying the electrical bills we currently do, if the heat was sufficient....but it's not. There are cheaper ways to get better heat...I could put in a wood boiler like my cousin has. Their house is *nice* and comfy during the winter. But he's already beginning to hate the amount of work and mess that's involved, and I just decided I didn't want that. So this still seems to be the right way to go.

 

[beelzerob]

Sorry about hijacking the other thread. I would move my post but don't know how to do that.

Hehe...oh, it happens so often as to not matter. The only reason I start new threads is just because it becomes so hard to find "that one thread where we talked about that stuff". So it's more of an organizational thing to me than a forum politeness issue.

You cant move your posts, but maybe the forum masters will.

 

[apostolakisl]

Sorry about hijacking the other thread. I would move my post but don't know how to do that.

Hehe...oh, it happens so often as to not matter. The only reason I start new threads is just because it becomes so hard to find "that one thread where we talked about that stuff". So it's more of an organizational thing to me than a forum politeness issue.

You cant move your posts, but maybe the forum masters will.

I'm in Austin TX. Air exchange heat pumps are not good if you have significant cold which we don't have. The units have to run defrost cycles and use strip heat which is not efficient. My worst heating month was high $300s and that was with some of the coldest weather Austin ever had. Generally Austin doesn't go below freezing but 10 or 20 days a year and even then for just part of the day.

I use propane and on demand hot water heaters. In one year I used 100 gallons of propane which also ran my cooktop and grill. That is about $20/month.

Drilling holes in the ground is pricey stuff and if something ever goes wrong, you have to drill a brand new hole. You also have to deal with issues like keeping it away from septic fields. If I lived up north and had 55 to 60 degree earth and a more even split between heating and cooling needs, I think geotherm would be more viable. With our 70 degree ground temp and then 8 months of pumping heat into dry limestone which isn't the greatest heat sink you start to lose ability to dump heat to Earth as I have been told by people with similar systems in the area. If the ground temp around the loops starts climbing to 80 or 85 you start realizing that the air outside isn't that much hotter (or even cooler at night) and a whole lot cheaper to access.

I kind of doubt you will need 8gpm to run the smaller system you are talking about. Water has a high coeficient of heat. With your friend talking $50k for 7 tons, that sounds better than the $80k I was quoted for 8 tons but sort of in the same ball park. I didn't have a bunch of choices of contractors on geo-therm. Also it could be that we are drilling in rock here.

 

[beelzerob]

Ya, that's a VERY good point about the defrost cycles. I didn't even know about those at all until I was in the basement one night and then thing made a tremendous blowing sound...I thought a line had busted or something, scared the bejeezus out of me. But once I learned what it was, then I started watching the HVAC temp probe I have during those times, and sure enough, it was basically turning on the A/C in the middle of winter! Boy will I not miss THAT particular feature of air exchange!

I considered the on-demand very strongly when we were putting our system together. However, we don't have natural gas, or I would have done it. I was able to calculate out some example costs for electrical vs. propane, and propane ended up being the most expensive option. It's much cheaper to go electrical, and now that we'll have the geo and a desuperheater, I'm glad we did. We only use our propane for cooking.

The ground here is about 20 ft of clay and then I believe limestone. Ground water temps are right around 50 deg. The eventual warming or cooling of the heating loop is what makes me want to avoid closed loop systems. I just simply don't want ANY excuse again for electrical heaters to come on.

Most every system we've looked at (water furnace, climate master) say just about 2gpm per ton. I'm going to put probes on the water outflow to see just how much the temp is dropped after it goes through the furnace. But since just about everyone is saying we need a 4 ton unit, that's 8gpm if both stages are running. Apparently, the factory default is that the full 8gpm will be used, even if you're only using the first stage of heating, but if you add some valves and stuff, then you can limit it to just what the first stage needs. Turns out the first stage is 3 tons and the 2nd is 1 ton, so it's a difference between 6gpm and 8gpm...not a big difference, but given how long it will be running, that will add up awful quick, so I think that's an option I will be going for.

It's true water holds so much more heat, and that's why I know we'll be getting BETTER heat out of this than we did with the air exchange.

I've talked to 4 geothermal contractors now and have 3 more up at bat this weekend, ALMOST all of which I feel very confident in choosing, so I feel good about my choices.

 

[apostolakisl]

50 degree ground water is good for both heating and cooling. If you have a vaiable speed well pump you should be able to measure the temp of the inflow water and outflow freon and install an electonic valve that lets more or less water flow depending on the temp. I car thermostat would do the trick perfectly if only they were designed to work at 50 degrees (not sure if they are acurate enough either)! The goal is basically to get the freon flowing out of the heat exchanger to be just a few degrees warmer/colder (depending on season) than the inflow water temp. You would need to consider multiple issues on water flow such as expense (not just money but environmental) of dumping all that water, as well as the electricity cost and wear on the pump vs the change in efficiency of the heat pump at various temps to determine that temp spread. ie how much change in efficiency do you get on the heat pump with 45 degree freon vs 46 degree freon on the heat cycle?

You also need to consider the possibility of your well going dry during a drought. For that matter any failure on your well will also be a failure of your HVAC. Fixing wells is sometimes a several day process depending on what is wrong.

My parents built a house in Harbor Springs Mi. The water (as you might guess by the name) just comes gushing out of the ground there all on its own. Why they didn't put in geotherm is beyond me. The water runs 42 degrees there. Their gas bill in the winter is several hundred dollars per month with the thing set at 58 and no one home. I can't imagine that a geotherm heat pump wouldn't blow that away on cost.

Do the geotherm heat pumps also let you use the heat pump to heat water in winter? It's obvious that dumping that heat into water in the summer is "free" heat but it might be nice to just skip a regular hot water heater all together and have the heat pump heat your water in the winter too. Heat pump water heating is a lot more efficient than standard resistance heating. Then you could run a continuous loop of hot water through your house and have "instant" hot water at all of your faucets. In the winter time that would not even be wasteful as all of the heat that escapes the water would just go to heating the house.

I really like my tankless hot water heaters. They make electric versions but the electric company won't let you use them because they take a huge wattage draw when on. Even if they did I would have had to up my service panel from 400 amp to 600 amp which would have been a stupid waste of money. Water temp around here is so high to start with, even in the winter, that it really isn't that big of a deal to heat it.

 

[beelzerob]

Oh, I love to tweak, but I'm going to leave the water-rate decisions to the unit. That's beyond what I feel confident playing with.

Wear and tear on the pump is a consideration, and was one of the most significant early reasons why NOT to go with open loop. And true there is pump electrical usage costs too. But I consider the efficiency benefits worth the risk and cost.

It would be a pretty significant drought to cause our well to go dry, and really it would go dry regardless, since we'll be putting the water right back into the ground via a return well. So we'll still only be using what we normally use, as far as removing water.

The other safety we have is a very good wood fireplace in our main living area. That was a concession to the eventual massive snow/ice storm we're sure we'll endure, so if the electricity goes out (or our well pump), we can survive just fine with fireplace heat for as long as it takes to get it replaced.

Open loop geothermal with a high water table (or springs, better yet!) seems like a great idea, *if* you have some place to dump the water back. It won't go back into the ground, and from what I understand you can't dump it even into streams either without possibly running into environment issues. Probably the same for ponds/lakes (though I'd guess you could hide it better there).

 

[86turbodsl]

Also regarding the geotherm thing, I was super interested in doing that for my new house but it really doesn't pay off, at least not where I live having to drill the holes. I got a top of the line SEER 19 carrier infinity two stage with all the bells and whistles for $30k (8 ton). The geotherm was $80k for one bid (8 ton) and $60k (6 ton) from a different contractor. The 6 ton guy was the only one who believed that would be enough. I have lived in the house 15 months. It is an all electric heat pump house. My worst bill was $400 and that was August when it was over 100 every day. My total anual electricity for the year was about $3k. Let's say $2k was the heat pump. If the geo therm was 50% more efficient (which it isn't) then it would save $1k per year. Even if it saved $2k per year, that is a bad way to invest $50k. I think geotherm is probably great if you have a lake to dump the heat into or a really shallow water table where you can pump water up to heat/cool the coils.

$60-80K???? A you fricking kidding me?????

I have geothermal in my house. The loop field was $1600/ton. The heat pump was $2700. The air handler was $1250. Mine is 3 ton hp, 4 ton loop (water to water has to be a bit larger loop), even if I paid double what I have in it, it'd still be 1/3 of your LOW quote.

Are you drilling vertical loops through solid rock or something???
(edit) Ok, solid limestone. Didn't see that.... ok, maybe geo is not for you....!!

 

[beelzerob]

I'm pretty consistent quotes of around $10k for just the inside work. So, the unit and installation....that's it. That doesn't count anything outside the house, no matter which method. Did you install your own unit? I'm not sure I could buy a water furnace or climate master on my own....as in I don't think anyone would sell it to me directly, right?

Maybe the price has gone up with the popularity of it....maybe it's high here because of the small customer base....or (more likely) maybe it's gone up because they know people get 30% back in taxes. Hmmmm...

 

[pjwinstalls]

I have a 7200sq ft house with Climate master tranquility 20 system. 12 tons. (3) 4 ton units. They use about 12gpm each. I have a Grundfos variable speed pump with a open well and a return well. Where i am though, I have water at 30ft.

I paid 20k for the climate master units and all the valves etc... total. So figure $6200 for one. This is one of their most energy efficient units though.

I bought them direct from a distributor myself. All they require is a epa level 2 certification card. Most local hvac supply houses give the test which is pretty easy. You can buy a study guide for like $50.00.

The markup on them is crazy, so try and buy it yourself.

Flex ducting you can do yourself. You can go to ACDIRECT.com and they will design the entire system and layout, then sell you all the duct and supplies.

I dont know if any of this helps.....figure i'd throw it all out there,

I'm pretty consistent quotes of around $10k for just the inside work. So, the unit and installation....that's it. That doesn't count anything outside the house, no matter which method. Did you install your own unit? I'm not sure I could buy a water furnace or climate master on my own....as in I don't think anyone would sell it to me directly, right?

Maybe the price has gone up with the popularity of it....maybe it's high here because of the small customer base....or (more likely) maybe it's gone up because they know people get 30% back in taxes. Hmmmm...