The geothermal discussion thread

[beelzerob]

I've been known to do some pretty crazy things to save some money, and we ARE talking some pretty serious money here...but I don't know if I have the guts to go it alone.

Are you sure your units use 3gpm/ton? I was being told 2gpm/ton, pretty consistently.

Water at 30 ft. Geez. And you have a return well? I guess what my well driller said is correct...if an aquifer produces water, it will take water too.

 

[pjwinstalls]

Different units have different GPM needs. The tranquility 20 is 3gpm. Others are less.

I found setting up cqc interface a hell of a lot harder than install my geothermal system!!

Return well easily takes the water. I have never had an issue since i have had it for the past 4yrs.

I've been known to do some pretty crazy things to save some money, and we ARE talking some pretty serious money here...but I don't know if I have the guts to go it alone.

Are you sure your units use 3gpm/ton? I was being told 2gpm/ton, pretty consistently.

Water at 30 ft. Geez. And you have a return well? I guess what my well driller said is correct...if an aquifer produces water, it will take water too.

 

[beelzerob]

Ok. I was recommended the 27 series. 3gpm would be hard to handle, even with my required pump upgrade, in that I'll be spending more and more for the water pumping itself.

What you say is very interesting and worth investigating, though certainly your return of effort was more than I'd get, since you had so many units.

So you bought the units and then hired someone to install them? Who honors the warranty then for the system?

Is there some place I can go and find the prices of these systems if I were to buy one myself?

 

[apostolakisl]

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....!!

The drilling is $8/ft and I believe there were 8 250 ft holes for about $16k in drilling. Then you have to pay for all of the pipe that goes in the holes and backfilling with that heat transfer mud like stuff they use. The bids I was putting up are for the entire install on a new house, not just the geo therm part.

I just checked my well pump specs. It can put out about 25gpm and is 800 feet deep (5hp). At full throttle the bugger eats up about 5kw. So for me to use open loop with 8 tons running (16 to 24 gpm depending on who I read) would be 4 or 5kw on top of the compressor and air handler usage. Plus I would need to deal with the water, likely meaning a second well which could probably be 600 to 700 feet deep.

The guy who did his own install must have a lot of free time on his hands. I love doing that kind of stuff but holy smokes, a 7000sf house and you did the entire HVAC on your own! I could see pulling a couple of weekends on a 2500 sf house or something.

I do have to say, most hvac guys are idiots. The geo therm installers seem to be the only ones who actually understand what they are talking about. The guy I ended up using didn't have a clue about any of the physics of anything he does. The system does work very well however.

 

[DavidL]

Living on a lake, I have an open loop system. But, I might have looked into this if I was to do it again
http://awebgeo.com/AWEB85c0.html?file=SlimJim.asp

The amount of energy use for the water pump is trivial compared to the compressor electricity. If your well can maintain the amount of water needed, who cares about the water use.

As far as purchasing equipment, go find a local distributor for the system you want, walk in and buy it....if you have done enough research to know what to buy, and have enough hands on experience to properly install it, then you're money will have welcome arms. If you don't have one or the other, then hire it out.

As a reference, my 5 ton geo system (plus two stages of electric heat which adds another 2 tons) was about $4K for the heater / air conditioner. I also have a 110K BTU propane furnace as a backup for power outages that runs in parallel. The forced air duct work was installed by a HVAC contractor, and I installed the control system and heat plant. We both worked on the plenum connectors. I installed the radient floor heat piping before the floor was poured, but haven't connected that and probably won't.
The house was designed with energy efficiency in mind (other than lots of windows which are energy suckers) so the 5 tons goes a long way. (37 foot high ceilings on main floor, 10 foot on lower level, 6500 sq ft). The garage can also be tied in, but typically I don't heat it. It has it's own propane furnace if I want to work on a project out there in the winter.

When the house was first built and the geo wasn't functional yet, the house was heated on propane. The price tag was a killer....the geo has more than paid itself off.

$80K for heat...wow...I gotta assume most of that is for the wells but even with that...that's expensive. My 170 foot bedrock 4 inch casing well with all hardware (80 gallon tank / 1hp pump) was $4K. It's hard to say that's "too expensive" without knowing all the local issues and contractor pricing. If you had the land, I'd spend half of that digging a really nice pond / lake and look into the plate exchanger...

 

[apostolakisl]

Living on a lake, I have an open loop system. But, I might have looked into this if I was to do it again
http://awebgeo.com/AWEB85c0.html?file=SlimJim.asp

The amount of energy use for the water pump is trivial compared to the compressor electricity. If your well can maintain the amount of water needed, who cares about the water use.

As far as purchasing equipment, go find a local distributor for the system you want, walk in and buy it....if you have done enough research to know what to buy, and have enough hands on experience to properly install it, then you're money will have welcome arms. If you don't have one or the other, then hire it out.

As a reference, my 5 ton geo system (plus two stages of electric heat which adds another 2 tons) was about $4K for the heater / air conditioner. I also have a 110K BTU propane furnace as a backup for power outages that runs in parallel. The forced air duct work was installed by a HVAC contractor, and I installed the control system and heat plant. We both worked on the plenum connectors. I installed the radient floor heat piping before the floor was poured, but haven't connected that and probably won't.
The house was designed with energy efficiency in mind (other than lots of windows which are energy suckers) so the 5 tons goes a long way. (37 foot high ceilings on main floor, 10 foot on lower level, 6500 sq ft). The garage can also be tied in, but typically I don't heat it. It has it's own propane furnace if I want to work on a project out there in the winter.

When the house was first built and the geo wasn't functional yet, the house was heated on propane. The price tag was a killer....the geo has more than paid itself off.

$80K for heat...wow...I gotta assume most of that is for the wells but even with that...that's expensive. My 170 foot bedrock 4 inch casing well with all hardware (80 gallon tank / 1hp pump) was $4K. It's hard to say that's "too expensive" without knowing all the local issues and contractor pricing. If you had the land, I'd spend half of that digging a really nice pond / lake and look into the plate exchanger...

My 800 foot water well ended up at $16k for the entire job. That was the cheap bid. The other was $21k. The $21k guy was the most popular driller in town. I took a chance on the less known guy and it seems to have worked out fine.

There is a huge difference in electricity consumption for 100 foot well vs 800 foot. My dad had a .5hp well at his house with an 80 foot water table to get the same amount of water I get with a 5hp well at 800 feet. 5kw is 50 cents per hour. In the summer the unit would be running about 80% of the time or maybe 20 hours per day. That's $10/day or $300 per month just for the well pump. Obviously, no one pumps water here for geo therm.

 

[beelzerob]

(37 foot high ceilings on main floor

Hehe...sorry, I just can't get my head around that. That would be like me standing in our basement and looking up to the underside of our roof. I mean, that's warehouse tall. That would be awesome for an indoor rock climbing wall.... I pity you having to change light bulbs in there.

From what I'm seeing, the well alternates between 1700 and 2500 watts @ 8gpm (2100 avg) and 1400 to 2400 watts @ 6 gpm (1900 avg). The system should be running at 6gpm the vast majority of the time.

My current air exchange heat pump uses around 4200+ watts (indoor and outdoor combined). So, that means that my geo system would have to use less than 2300 watts for me to be saving any electrical costs at all. Is that likely? I suppose I can find that info on the units online somewhere.

Of course, the other way I'd be saving money is by it not running nearly as much or as long because it will be working so much better. And that part is very difficult to quantify. And then of course, there are the hot water savings too (though that is also minimized since our system will run the vast majority of its time in winter, not summer).

 

[apostolakisl]

(37 foot high ceilings on main floor

Hehe...sorry, I just can't get my head around that. That would be like me standing in our basement and looking up to the underside of our roof. I mean, that's warehouse tall. That would be awesome for an indoor rock climbing wall.... I pity you having to change light bulbs in there.

From what I'm seeing, the well alternates between 1700 and 2500 watts @ 8gpm (2100 avg) and 1400 to 2400 watts @ 6 gpm (1900 avg). The system should be running at 6gpm the vast majority of the time.

My current air exchange heat pump uses around 4200+ watts (indoor and outdoor combined). So, that means that my geo system would have to use less than 2300 watts for me to be saving any electrical costs at all. Is that likely? I suppose I can find that info on the units online somewhere.

Of course, the other way I'd be saving money is by it not running nearly as much or as long because it will be working so much better. And that part is very difficult to quantify. And then of course, there are the hot water savings too (though that is also minimized since our system will run the vast majority of its time in winter, not summer).

I doubt the geotherm heat pump will be that much more efficient. It seems to me you need a closed loop system to save energy. You might check also on one of the high efficiency air to air heat pumps. The SEER 19 units would have to beat a geotherm system with your well pump electricity factored in. The only thing is I believe you live far enough north that air to air doesn't work so well in the winter. If you have enough land you can also trench instead of doing a well.

Too bad there isn't a way to put a little turbine at the bottom of a return well to recapture some of that energy from pumping it up.

 

[beelzerob]

One of the well contractors said that I'd be looking at $6k more for a closed loop system. If my pump used 2kW, and elec was $.10/kWh (which is close enough), then my pump would have to run 3 1/2 years straight to make up that difference.

Of course, thats a pretty dumb comparison, since I could pay 5 1/2 years of $300 electric bills (which we haven't paid yet) with the $20k this whole install will cost me....

I have to keep reminding myself that this is about *better* and *consistent* heat, not necessarily cheaper heat (though i believe it still will be cheaper).

 

[apostolakisl]

One of the well contractors said that I'd be looking at $6k more for a closed loop system. If my pump used 2kW, and elec was $.10/kWh (which is close enough), then my pump would have to run 3 1/2 years straight to make up that difference.

Of course, thats a pretty dumb comparison, since I could pay 5 1/2 years of $300 electric bills (which we haven't paid yet) with the $20k this whole install will cost me....

I have to keep reminding myself that this is about *better* and *consistent* heat, not necessarily cheaper heat (though i believe it still will be cheaper).

This is the problem as I saw it with geotherm. To really make it the super efficient system it is touted as you have to deal with very high start up costs. You might actually be more efficient using a high efficiency air to air heat pump like I have with propane or nat gas kicking in when the temp goes below 35. 2000 watts for the well is not insignificant. If your HVAC is actually on 50% of the time over the course of a year, that is about $900 or about $75/month. For a system of your size that seems like a lot.

Do you have enough soft land to run a closed loop trench? You can even rent your own trencher and do that. Of course you need soft enough soil or you will be cutting forever.

 

[beelzerob]

We live on 10 acres, but we basically cleared only enough trees to fit the house (the whole lot is wooded), and we're definitely not going to kill trees for enough area to do that. So horizontal loops is definitely out. And I probably wouldn't go with those anyway if given a choice due to their decreased efficiency. I think that's what still draws me to open loop despite the pump costs.

I think I can safely say that our HVAC won't be on even close to half of the year. We've gone the past week almost without it coming on at all. Spring and fall is very nice and mild, and then in summer, I think our A/C only came on a few times each week. It's really only in winter that the system works.

I thought I'd be losing a lot of power draw going to water exchange just because the entire outdoor unit is going away, and that's the largest breaker in the panel.

If I look at the whole system, including hot water heater, I think overall I'm still going to be using less power than I am now. It just won't be as drastic a drop as I'd experience with closed loops.

 

[apostolakisl]

We live on 10 acres, but we basically cleared only enough trees to fit the house (the whole lot is wooded), and we're definitely not going to kill trees for enough area to do that. So horizontal loops is definitely out. And I probably wouldn't go with those anyway if given a choice due to their decreased efficiency. I think that's what still draws me to open loop despite the pump costs.

I think I can safely say that our HVAC won't be on even close to half of the year. We've gone the past week almost without it coming on at all. Spring and fall is very nice and mild, and then in summer, I think our A/C only came on a few times each week. It's really only in winter that the system works.

I thought I'd be losing a lot of power draw going to water exchange just because the entire outdoor unit is going away, and that's the largest breaker in the panel.

If I look at the whole system, including hot water heater, I think overall I'm still going to be using less power than I am now. It just won't be as drastic a drop as I'd experience with closed loops.

Of course it all has to do with your needs. The less the unit runs in your climate the less important efficiency is and the less willing you should be willing to lay out big bucks on the start-up costs. If your unit is sized properly it should run close to 100% of the time during your hardest season. For us, that would be July through Sept when the temp is typically 100 degrees everyday. If you your heating and cooling seasons are short and you have lots of time with windows open, it tends to make little sense to spend much money on your HVAC system at all.

 

[beelzerob]

Hmm...a valid point. I'd say that the heating season isn't short at all, but the cooling season is, and the inbetweens are just about fine. Sounds like just the opposite of yours. But even if it ran 24 hours a day during heating season, then overall our system still won't be running 50% of the year.

I guess the main drive at this point is because I'm disappointed with the "heat" coming from our current system during the depth of winter. I just find it insufficient. Duct temps get down below 90, which means it's barely heating the house when it comes out the vent. And that's how the house feels...barely heated. I'd say if the house felt comfortable through the winter, then we'd probably be fine with what we have now and the electric bills we have.

We don't have many options as far as getting better heating. We could get a higher seer air-exchange unit, but when the temps outside get down to 10 or lower, we'll once again I'm sure have the same issue of it just not producing what I'd consider to be heat. We really can't go to another form of fuel for our heating, as that would require a lot of infrastructure change, AND whatever fuel we use would be incredibly expensive. We could go to wood as my cousin did, as his boiler works great, but that's mess and work and maintenance, and apparently some risk too.

We do use a lot of hot water too, due to our double walk-in shower. So that's another reason to go geothermal vs. some other mechanism.

I think maybe my next step in this is to ask for references from some of these contractors, especially for people who are in my situation where they've swapped out an air exchange unit for geo, hopefully open loop, and see if they like the difference.

 

[sic0048]

If your unit is sized properly it should run close to 100% of the time during your hardest season.

While a properly designed system with the right size unit is critical to energy savings, a properly designed system should not run 100% of the time at the extreme. At least not if your house is properly insulated and as air tight as possible. The closer it runs to 100% of the time, the less likely your system is designed properly, or the less air-tight your house is.

 

[beelzerob]

I think I understand what Lou means. It kind of matches what the contractors were telling me.

They said that they do the heat/loss calcs not only to make sure I have a large enough unit, but also so that they don't OVERSIZE the unit. They said if I get too big a unit, then it heats the house too quick and cycles the unit too often. Under that theory, then during the worst heat loss period for the house, the unit would be operating near continuously.

That might also possibly explain why the number of BTU's the unit is rated at doesn't match the number of BTU's they calculated I would be losing during cold conditions....as in, the unit does not provide the number of BTU's I'm losing. I'm not saying it DOES explain it, because it still doesn't make sense to me, but maybe it does explain it.