Geothermal - what if?

[LD1]

I think you are wasting your money for the little gain.

Think about this......a house with no air conditioning but a full basement. Hot 85-90 degree summer days. The basement slab and below grade walls will rarely get above 50 degrees, so you would think there would be a real pronounced cooling effect in the basement. But you would be lucky if the basement stayed 10 degrees cooler right?

Now just think in reverse. 45-50 degree slab (with no below grade concrete walls to help) and outdoor temps of 0F and no other heat source, I doubt you would be able to keep the garage much above 10 degrees. Infact I would be worried about your lines freezing in the concrete with sustained 0F days. For 5000sq ft you would want SHORT runs and flowing pretty fast to a manifold. And SEVERAL to cover that size slab. Which will require a heck of a pump. Just running a single LOOOONG loop or two in 5000sq ft, your water would have done given up its heat and froze by the time it got to the end unless you were pumping it through very fast.

 

[Jim Timber]

Our basement stays cool year round. Wife can't live without A/C - which is why I'm trying to reduce the demand on that system as much as possible.

0-10F for a couple days is cute. We're talking lows in the -20F's highs of -5 for a sustained period.

I have access to lots of wood, but I want the main system capable of being autonomous in the event we're not here.

As for failed pumps - it's within the top 5 threads on this page. Guy's spending $1600 on a motor or $3600 on a replacement unit that's not 10 years old.

Our house isn't particularly well insulated and we have a natural gas furnace which costs us around $200/mo for a 2600sf floor plan (two stories, 1300sf foundation) to heat and roughly $100/mo to cool and power the lights/oven/stove etc. Electric rates aren't very different where the new shop and house are going. Wife insists on keeping it 74F in the summer. I'd rather drop it down to 72F if it didn't add so much to the bill.

 

[davesl708]

What is this talk of short lived geothermal pumps? Granted I have only been living in my house for 18 years, but my system keeps working. OK, I was victim of the crummy quality coil common 18 years ago in practically all systems and it started leaking. Coil was replaced and all is good again. The brand I have reportedly has had systems in service 30-40 years. My neighbor has a tech at her house 3-4 times a year for her not geothermal system. The rest of the neighbors have heat pumps and traditional systems without all the service calls. I question her install as at most, a visit every few years to check the system should be enough.

I have a tack room in the barn. Concrete slab. 1" foam caulked to the outside walls and r19 fiberglass in the ceiling and walls. An incandescent light bulb keeps the room above freezing when we get our 0-10F spells.

I don't understand the problems with other units either. I went with geo due to five people I know use geo and have never had a problem. My barber's geo is 25 years old and still working fine. Others have had theirs for 10 years and no problems.
My garage is not heated just well insulated. A warm engine keeps it above freezing when down near 0. I use CFL lights and that helps as well keeping above freezing.

 

[Jim Timber]

What's your electric bill using the 25 yr old system and what volume of air is being heated?

CFL's are junk. I've never had one live to it's expected lifespan. We'll be going LED on everything in the new house.

 

[davesl708]

What's your electric bill using the 25 yr old system and what volume of air is being heated?

CFL's are junk. I've never had one live to it's expected lifespan. We'll be going LED on everything in the new house.

My barber has no complaints with the cost to operate his 25yr old system. I don't know what he pays for his place.

My system is 5yrs old. I heat/cool 1350sft. I have total electric house with a large hot tub running year round. Winter bills (4 mo.) run between $94 and $124. Summer cooling (6 mo.) run $55 to $65. Two months out of the year the bills are around $39 to $49.
The best part is I don't have to listen to a noisy outside unit sucking up electricity for two motors or pay $29 per month to the gas company for the privilege of just hooking up.

 

[Jim Timber]

We don't have natural gas available, so there's only the $25 fee of being hooked to the power lines. Well water, septic system waste.

 

[Tig]

I have a Rockton geothermal unit. In summer the cooling is passive. No compressor at all. I seem to recall the CoP is 14.
My configuration is open loop. It uses a source well and a return well.
It cools the house very nicely. I also have powered attic fans, which are a huge help in keeping the house cool.

 

[Jim Timber]

I think you are wasting your money for the little gain.

I'm not wasting any money. I'm asking questions 6 months ahead of the first pour because I don't want to waste money.

 

[fidowanttobe]

I have a 16 year old 5 ton unit that I would do again without a doubt. 1800 sq.ft x 2 floors. 2x4 walls upstairs that I am almost done firring out to 2x6 and R19 and updating very crappy windows, so I hope the monthly will decrease eventually. Average $60 to 100 a month. Basement is unfinished but insulated except for the tuck-under 30x30 garage which is finished and heated. Only thing I would do different is I would heat the floor downstairs. LOVE the heating and the cooling is even better. Very constant temperature. Only maintenance needed is filters.

 

[LD1]

0-10F for a couple days is cute. We're talking lows in the -20F's highs of -5 for a sustained period.

Only makes my point more valid.

As for failed pumps - it's within the top 5 threads on this page. Guy's spending $1600 on a motor or $3600 on a replacement unit that's not 10 years old.

Even if you are one of the unlucky ones that has to replace a pump after 10 years (which is NOT common), it is still better than spending the money on a system that WONT WORK.

There is a reason why people dont just hook their wells up to their pex loop in the concrete.

You would have MORE benefit if you took the kw required to pump the water, and converted that kw straight to heat. (resistance heater, light bulbs, whatever). I think that would get you MORE heat in the building for the same consumption of watts