The geothermal discussion thread

[2blackbelt]

Hey guys, wanted to chime in on the geothermal. I built a new 9000 sq. ft. house with 7800 heated/cooled last year. Have lived in the house over a year and my average electrical bill is $225.00 per month. I have two 4 ton geothermals from waterfurnace. I used foam insulation in walls and ceiling. With Blow in insulation the specs called for 12 ton but by using foam insulation it cut it back to 8 ton. I am well pleased. They buried 770 feet of piping at 8 and 6 foot levels below ground. My highest bill is in Jan because below a certain temp the heat strips kick in. Also used low E windows and marathon water heaters. My house is ALL electric except for my built in bbq grill. I am well pleased with it. Total cost for all ductwork and units was $35,000. But that was everything starting new. I cannot remember the cost of the units seperated from ductwork. Were on Entergy electric which has some of the highest rates in the south. I live in Walnut Ridge, Arkansas.

 

[beelzerob]

I'm getting close to finally having all the info I need to make the decision. I'm still just a little on the fence about open loop vs. closed loop, since the last guy i talked to really minimized the impact of a closed loop water system water temp lowering over the course of a winter. It looks like the pump upgrade will cost me about $1600, which is of course still way less than the extra $6k for closed loop...but it doesn't take into account pumping costs of electricity.

*sigh*

I just wish sometimes things would be cut and dried.

 

[apostolakisl]

I was playing with the settings on my HVAC system and found that it maintains a log of everything. It keeps track of number of hours the units have been attached to electricity and the number of hours running in all of the various modes (high heat, low heat, high cool, low cool, defrost). I did the math and it turns out that my units have been running about 20% of the time since power was turned on. The first couple of months the units had power we hadn't moved in but the heat was on periodically. Most of the time was spent in the low modes (they are two stage units). My guess is that over the course of a year of actually living in the house they probably spend something like 23% of the time operating.

It also tells you rpm's on the fan, voltage levels, cubic feet of airflow, any faults that occur, and other stuff. It is kind of interesting to see all of that stuff.

It's the carrier infinity system. You access the info from the thermostats.

Lou, where or how were you getting all those juicy tidbits of runtime, RPMS, etc? From the thermostat LCD itself? From a serial port?

On the Carrier infinity that info is all available at the thermostat. You have to know the trick to get into it. Push and hold the "advanced" button for about 10 seconds and it puts you into the service tech mode. All kinds of data is in there as well as a bunch of parameters that you can set up.

 

[apostolakisl]

Hey guys, wanted to chime in on the geothermal. I built a new 9000 sq. ft. house with 7800 heated/cooled last year. Have lived in the house over a year and my average electrical bill is $225.00 per month. I have two 4 ton geothermals from waterfurnace. I used foam insulation in walls and ceiling. With Blow in insulation the specs called for 12 ton but by using foam insulation it cut it back to 8 ton. I am well pleased. They buried 770 feet of piping at 8 and 6 foot levels below ground. My highest bill is in Jan because below a certain temp the heat strips kick in. Also used low E windows and marathon water heaters. My house is ALL electric except for my built in bbq grill. I am well pleased with it. Total cost for all ductwork and units was $35,000. But that was everything starting new. I cannot remember the cost of the units seperated from ductwork. Were on Entergy electric which has some of the highest rates in the south. I live in Walnut Ridge, Arkansas.

That sounds like a great price. I paid almost that much for 8 tons of carrier infinity regular heat pump. You must have easy trenching soil. Your climate I think is a little milder as well. In Austin, we can go for two months in the summer with an average high above 100 and an average low above 80.

I got two bids for geotherm one for a 6 ton $60k system and another for and 8 ton $80k ton system. Both needed to drill a bunch of verticle loops. 6 tons might have been cutting it close. For the last few days we have had highs in the mid 90's and lows around 60. I only have turned on 5 of the 8 tons of HVAC and it is keeping up, but just barely.

It's funny that your heat strips were still needed with geotherm since you wouldn't expect the ground to get too cold to extract heat like with air to air heat pumps. Perhaps it is becuase 8 tons is too small a unit for really cold days.

I also did the spray foam and low E Pella windows. With that good of insulation, I never ever feel a draft of any sort in addition to the low energy bills. In my mind, that stuff is a no brainer.

You must not have a bunch of kids to have an electric bill that low. Last month my bill was $125 which was about 99% non-HVAC since the weather was so mild. I only have 6000sf.

 

[beelzerob]

The heat calcs I've been seeing all show that around the teens, they expect the heat strips to come on with my geothermal system too. It's not because the source temp is getting any lower, it's just because the heat loss is so much greater as it gets colder that the geothermal system can't meet the demand.

The nicest thing I can see is that when the need for more BTU's increases as the temp goes down outside, I don't see the corresponding drop in BTU's produced with a geothermal system that I see now with my air exchange system. So that means the geothermal system will take me down in temp much further than the air exchange did before the heating strips come on.

Either way, I'm not all that worried. We went all last winter without heating strips (because for some reason they stopped working....), and this next winter we'll have even better heat. Plus we have a centrally located wood fireplace that is enough to heat the entire 2nd floor. So I think we should be ok.

 

[86turbodsl]

6000 ft - 9000 ft !!!!!!


AND YOU'RE COMPLAINING ABOUT HOW MUCH IT COSTS?????

I just finished my 2950-ish ft house. It cost me about $125 / ft building it myself.

I'm pretty upper middle class degreed engineer. I can barely afford it and it is a mansion in the eyes of most of my neighbors.

WHERE THE HECK DO YOU BUILD almost 10K foot houses????

Sorry, I'm done ranting now. I am just struggling to wrap my mind around a house that big that isn't a boarding house or something.

 

[beelzerob]

Geez tbldsl, you've been around long enough now to know that this site attracts all kinds. Heck, I complain when we have to spend $20, so I think it'd make sense to resist $35k, no matter how much you have. There's a few houses around my neighborhood probably close to those sizes, and amusingly, they seem to have the same issues of building vs. cost that I have.

One particular neighbor friend of mine was complaining to me that his new 3 car garage is too small and he might have to build another external garage. And I told him that *his* garage is the garage I would build out of frustration that my current garage is too small. And the garage I have now is the garage I built out of frustration that my LAST garage was too small.... We both agreed that it is never ending and affects everyone.

My eye popping moment in the forums was when someone posted they had 35' tall ceilings. I mean...I just can't phathom having to change light bulbs up there, or how you minimize the echo. I've been in hangers with lower ceilings. But *shrug* there's all kinds of creative houses out there.

It's amusing to know that despite that, we all come to these forums equally scratching our heads.

 

[jrfuda]

Good info keeps coming... All the talk about spray foam insulation is making me think we should start another thread just about that, or maybe a whole energy saving forum (E, are you listening????). It's something I plan on incorporating into my upcoming renovation and would like to get some first hand info on install, cost and living with the stuff. I think the geothermal, good insulation and windows are all things I want to incorporate into the home... given the time scale of the renovation, though, these will all be done when it's near completion, about 5 years from now...

I'm sure beelzerob will have lots to report about his install by then!

 

[beelzerob]

Actually, I have some *good* news to report NOW.

The house just passed the cash for caulkers bill, which if passed and made law, would boost the tax rebate for geothermal systems from 30% to 50% (with a cap of $12k).

The only thing I don't know about that is IF it happens this year, will it apply to installations in 2010, or starting 2011, or starting when they actually pass the bill. That will certainly affect when I decide to have them do the work, as it would mean an additional $4k back for me.

 

[jkish]

Good info keeps coming... All the talk about spray foam insulation is making me think we should start another thread just about that, or maybe a whole energy saving forum (E, are you listening????). It's something I plan on incorporating into my upcoming renovation and would like to get some first hand info on install, cost and living with the stuff. I think the geothermal, good insulation and windows are all things I want to incorporate into the home... given the time scale of the renovation, though, these will all be done when it's near completion, about 5 years from now...

I'm sure beelzerob will have lots to report about his install by then!

I've been looking into spray foam in my attic and would be interested in discussing as well.

My biggest unknown right now is the question of fumes / chemical sensitivity that have been reported by some.

 

[WayneW]

Good info keeps coming... All the talk about spray foam insulation is making me think we should start another thread just about that, or maybe a whole energy saving forum (E, are you listening????).

It is a good idea, but it opens a whole can of worms and massive YMMVs. I am shopping for a new heat pump (Florida, standard split HVAC system) and upgrading insulation, etc. I am finding all sorts of conflicting information depending upon your exact house construction method, style & location as they make a huge difference. Finding people that can actually calculate/predict an ROI without making totally random guesses are scarce as hen's teeth. I am NOT going to spend $10k on spray insulation because the salesman thinks "it is a good idea that might save some money". People try to sell me solar water heaters that will save me $50/month (or whatever) on my electric bill when I know I only pay $10-15/month for hot water NOW. <frustrated sigh>

 

[apostolakisl]

Good info keeps coming... All the talk about spray foam insulation is making me think we should start another thread just about that, or maybe a whole energy saving forum (E, are you listening????). It's something I plan on incorporating into my upcoming renovation and would like to get some first hand info on install, cost and living with the stuff. I think the geothermal, good insulation and windows are all things I want to incorporate into the home... given the time scale of the renovation, though, these will all be done when it's near completion, about 5 years from now...

I'm sure beelzerob will have lots to report about his install by then!

I've been looking into spray foam in my attic and would be interested in discussing as well.

My biggest unknown right now is the question of fumes / chemical sensitivity that have been reported by some.

HMMMM. retrofit spray foam. I don't know if that will pay off. New construction is a no brainer. The thing about retrofit is that I don't know that you will really get the value out of it since you won't have the opportunity to truly seal everything up. The r-value really isn't that much better versus fiberglass batts, it is the air infiltration that makes the gigantic difference. Unless you tear everything down to studs, it is tough to get it to work properly.

It is nice to have the insulation on the underside of the roof deck, though. The attic never gets above 85 even on 105 degree blazing sun days with no air vents in the attic.

 

[jkish]

Good info keeps coming... All the talk about spray foam insulation is making me think we should start another thread just about that, or maybe a whole energy saving forum (E, are you listening????). It's something I plan on incorporating into my upcoming renovation and would like to get some first hand info on install, cost and living with the stuff. I think the geothermal, good insulation and windows are all things I want to incorporate into the home... given the time scale of the renovation, though, these will all be done when it's near completion, about 5 years from now...

I'm sure beelzerob will have lots to report about his install by then!

I've been looking into spray foam in my attic and would be interested in discussing as well.

My biggest unknown right now is the question of fumes / chemical sensitivity that have been reported by some.

HMMMM. retrofit spray foam. I don't know if that will pay off. New construction is a no brainer. The thing about retrofit is that I don't know that you will really get the value out of it since you won't have the opportunity to truly seal everything up. The r-value really isn't that much better versus fiberglass batts, it is the air infiltration that makes the gigantic difference. Unless you tear everything down to studs, it is tough to get it to work properly.

It is nice to have the insulation on the underside of the roof deck, though. The attic never gets above 85 even on 105 degree blazing sun days with no air vents in the attic.

Three reasons I'm considering it:

1) Infiltration as you mentioned.

2) HVAC and ductwork in the attic that would be exposed to lower temperatures.

3) History of pests - squirrels etc so existing fiberglass is soiled and sealing might keep them out.

Price including removing existing blown fiberglass < 1.50 a sq ft and a $1500 tax credit.

 

[2blackbelt]

Spray foam was a no brainer for me. I have 9 foot walls on two floors and 8 foot on the 3rd floor. With the size of the house and the reduction in tonnage for the geothermal saved me 4 tons of geothermal. It cost me $14,000 for insulation (Walls and ceiling). It was going to cost me $10,500 for blow-in insulation. I'm sold on it and my builder is too. He has built 6 houses since mine and every one has foam insulation. Like I said, Heating/Cooling 7500 sq ft is averaging $225.00 per month electric.

For those talking about the size of the house, my original plans called for 4500 sq ft. By finishing out the attic over a 3 car garage and two second story rooms added that was originally supposed to be attic it added lots of sq footage. Remember, you already had the Floor rafters and ceiling rafters from a tall peak. Then I added stairs from the second story to the attic (3rd story). Maximized my space on the 3rd floor without adding to the ground sq footage. Remember once again, you already had rafters on the ceiling and the tall peak. It did not cost much to finish all that out. Every man needs a shop, i did attach a 30 X 40 additional 2 car garage to the house for my shop. It is well used between my 7 and 10 year in the winter. My tools and yard equipment also occupies that space. Oh i forgot, I added a second story above the shop because of the peak of the roof. Remember, I already had the ceiling rafters and the roof framing in between. A pet peeve of mine is maximizing space under the roof. Most new houses have tall peaks with lots of open attic. To me its a waste if your not using it the best you can. Thats how I ended up going from 4500 sq ft original plan to 9000.

I'm sold on the foam insulation. Just think about the foam Mcdonalds coffee cup. Paper thin but it doesnt burn your hand. Same concept for your house. Plus one interesting thing is that it fills every crack, hole and slit. Spray in fiberglass cant do that.

 

[apostolakisl]

Good info keeps coming... All the talk about spray foam insulation is making me think we should start another thread just about that, or maybe a whole energy saving forum (E, are you listening????). It's something I plan on incorporating into my upcoming renovation and would like to get some first hand info on install, cost and living with the stuff. I think the geothermal, good insulation and windows are all things I want to incorporate into the home... given the time scale of the renovation, though, these will all be done when it's near completion, about 5 years from now...

I'm sure beelzerob will have lots to report about his install by then!

I've been looking into spray foam in my attic and would be interested in discussing as well.

My biggest unknown right now is the question of fumes / chemical sensitivity that have been reported by some.

HMMMM. retrofit spray foam. I don't know if that will pay off. New construction is a no brainer. The thing about retrofit is that I don't know that you will really get the value out of it since you won't have the opportunity to truly seal everything up. The r-value really isn't that much better versus fiberglass batts, it is the air infiltration that makes the gigantic difference. Unless you tear everything down to studs, it is tough to get it to work properly.

It is nice to have the insulation on the underside of the roof deck, though. The attic never gets above 85 even on 105 degree blazing sun days with no air vents in the attic.

Three reasons I'm considering it:

1) Infiltration as you mentioned.

2) HVAC and ductwork in the attic that would be exposed to lower temperatures.

3) History of pests - squirrels etc so existing fiberglass is soiled and sealing might keep them out.

Price including removing existing blown fiberglass < 1.50 a sq ft and a $1500 tax credit.

If you are needing to replace the insulation anyway, I would do it.

As far as critters, don't expect the foam to keep them out. Make sure you close off openings, it is not hard for a squirrel to dig through the foam.