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Geothermal - The next project

Posted by beelzerob , 01 April 2010 · 986 views

Since this blog is the only one I have ever contributed to, and since our next project has at least *some* HA tie-in, I guess I'll just blab about it here.

We pondered getting a geothermal heatpump when we built our house in 2008, but the initial cost (+$20k) was more than we could handle.  We also thought at the time that our fireplace we were putting in (we ended up with a lot of wood on the ground just clearing the lot) would do most of the heating in winter.

Well, after our "beta" winter in 2008/2009, it became clear that the fireplace wasn't going to cut it.  It did *great* heating the upstairs of the house, due to our very open floorplan.  Just leave the bedroom doors open, and they were quite comfortable.  However, there was no way to get that heat to the first floor rooms, which all stayed uncomfortably cool.  The original plan had been to use the HVAC fan (which I could control through CQC) to circulate the air to the first floor, so the fireplace would be heating the whole house.  Well, the datanab temp sensor in the HVAC stack right above the fan told the truth about that...no matter how warm the upstairs was, the air wasn't getting above 65 at the fan...which meant it would be even colder once it came out the registers.  So basically running the fan only cooled down the house.  I guess that makes sense, as the cold air returns are largely just through vacant cavities in the interior walls, which no doubt bleeds a lot of heat into the wood and drywall.

So that left us with our air-exchange heat pump.  And that was disappointing as well.  On colder days (< 20 deg), the duct temp above the fan was barely getting above 80.  And (as is typical with heat pumps), the air coming out the registers just felt cool if not cold.  So I was overall just simply disappointed with the heating capabilities of the air exchange heat pump and fireplace.

Since I did not want to change to a direct fuel type of heat (we live out in the rural hills, so there is no natural gas option), that really only left geothermal.  I had become a believer in the theory behind it.  But overall, I wasn't really in it for the energy savings or the "green"-ness of it...I just wanted better heat.

After that first cold winter, we talked to the HVAC contractor who installed our existing system and asked for an estimate for a geothermal install.  They came back with a quote for over $20k.  I thought that was a bit surprising, since when we were building the house, they said it was $20k more than a standard install....so that would mean $20k even though we wouldn't be paying for the existing air exchange install.  Now, without taking that into acocunt, it's still $20k.  Hmmmm.  Anyway, it was a good baseline, but also so much that we decided to give it another winter and see if it was really as cold in the house as we remember.

That brings us to today.  The last winter was as cold as we remember.  What is making it more attractive now is 1) We've managed to set aside some money, since this will be our one big project for the year (last year was the pole barn, year before the lawn), and 2) There's now the 30% tax rebates.  When we were building the house, it was 30%, but limited to $1500 max.  Now it's 30% unlimited.  On a $20k install, that means over $6k back in tax reduction.  A significant increase.  What's more, Obama is pushing an increase to 50%, limited to $12k.  THAT would be nice, but who knows what can get accomplished in Washington anymore...

Last weekend we had 4 contractors out, and I have 2 more well drillers scheduled and at least 1 more contractor.  Given this will probably rank in the top 10 of most expensive decisions we've made, I'll probably take quite a bit of time to decide on this.

How large is the house? What kind of insulation? Avg number of windows (more / less?)
Is your home forced air now?
Do you have A/C now?
What kind of domestic water heat do you have (electric / propane?)
Do you have propane now?
Where is the home (climate)?
Do you have zones now? If forced hot air - adjustable air vents?
Single furnace now? Propane?
Do you have any concerns about power outages? Geothermal takes lots of electricity.
Do you have a backup generator now? How many KV?
What kind of thermostat(s) do you have now and how many?
Do you have a well now? How many H/P? How large is the expansion tank? (gallons)
Do you have an area that water can be disposed? (lake / pond / culvert).

The above will give a good idea of what you are facing.

How many ton unit did your contractor specify?
Closed or Open loop system? How many feet? How many feet of trench? Or multiple vertical wells?
Do you have an open area that can be trenched? How many sq ft?
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Ya, we've answered all those questions, multiple times, since we've been pondering this for about a year. I feel we're pretty well versed in the options and what our heating requirements are.

Propane's not an option...way too expensive. MOST expensive fuel available to us, in fact.

Power outages aren't a concern. Thats why we have the wood fireplace. We also have a generator panel that we can use with our portable generator for the occasional power needs to keep us going should the catastrophe occur.

Both contractors that have given bids so far specify a 4 ton system. That matches what our existing heat pump is, so I guess makes sense, in that I would expect the geothermal unit to produce more heat for those 4 tons than our air exchange does on the coldest nights.
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beezlerob, I'll be watching this closely as it's something I'm really interested in. Thanks for posting the link in the other thread!
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No problem. I'm glad it can be useful info to someone! hehe. I'll definitely be posting as important steps happen or info is gained.
Got my 3rd estimate today, which amusingly fell right in the middle of the first two. When I get a few more I'll post about what the ballpark costs are, but I'm *HOPING* the whole thing will be under $20k.
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