Deep ground heat sourse pump
bubbleboba
| Posted in Energy Efficiency and Durability on
Hi New To The Forum.
Looking to install a deep ground heat sourse pump into my property.
Has anybody got any knowledge on this topic regarding most efficient model and overall costs
TIA
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Replies
By deep ground do you mean you will have a loop up and down several wells?
General speaking the math for ground source does not work even with a tax credit.
I have yet to see the BEopt calculation that would make a ground source heat pump with a lower cost to buy and operate over time compared to air source. It is a big world and every place has different weather and utility costs feel free to try and make the numbers work. Short of the guy that gets the loop install for beer by his brother it is a tough nut.
https://beopt.nrel.gov/home
Walta
It's expensive, probably $30k to $50k. It's hard to justify the cost right now. Its biggest potential advantage relative to air source options is that the peak demand on a cold winter night can be a lot lower than the peak demand of an air-source equivalent. If utilities start charging residential customers for peak demand, the value of that feature will become clearer. Something like that may happen in the next decade or two.
The highest efficiency will be from models that have variable speed compressors like minisplits have.
More likely that the numbers will work if you use water from an existing well.
So, I've got a real world example of this. My friend and I both built new houses at the same time.
Both houses are similar size (2100 sq.ft), and had similar budget. He opted for a geo-loop like you are suggesting, using a a 3 ton WaterFurnace Series 5. This was an expensive install, nearly $45k. It was too expensive to use zones, so he didn't do so.
I installed a 2.5 Ton Mitsubishi HyperHeat air source heat pump, that uses an air handler and is zoned. This was expensive as well, as far as furnace installs go, and I paid ~20k, but I have zones.
I then took an additional $10k, and added insulation under the basement slab, and insulated the basement to about ~R20 (Up from the R12), upgraded the spacer in my windows to be insulated, added insulation to my attic, bringing it up to ~R80 (from R60), and added 2" of rockwool to the exterior of my home (instead of 1").
Then, last year, during a cold snap, we compared notes. Surely the geothermal system, being immune to the colder air temperatures would outperform the air source system shivering in the -30C air? Turn out no.
I'm sure the COP of the geothermal system was higher over the time period, but reducing loads first, had a huge impact. Overall, I spent 80 kWh heating my home over the two day period we looked at, and he was over 100 kWh.
More insulation and cheaper HVAC appears to beat less insulation and geothermal.