Geothermal cooling system
Jamalbaloch
| Posted in Green Products and Materials on
Hello All,
If geothermal heat pump/AC have pump to circulate liquid through loops, then how it is gonna reduce cooling costs with that extra pump along with compressor (for freon)?
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Heat pumps use more energy to extract the same amount of heat the greater the temperature difference between where the heat is extracted from and where it's sent to. If it's 95F outside and 55F below ground it takes a lot less energy to extract heat from your house and dump it in the 55F underground than in the 95F below-ground. That more than makes up for the energy needed to circulate fluid.
The problem with geothermal is the high initial cost of drilling the wells.
There is some validity to your point in that every ground source heat pumps loop is made from different pumps with different sized pipes connected to loops of different length or wells of different depth. But in theory they should be able to produce more BTUs per kilowatt hour. The question become can they save enough to pay for the higher installation costs? My gut says no.
Just how efficient any given combination happens to be when connected to any given home in any given location is total unknowable. Your combination that may or may not be an efficient heat source you will never know for a fact it just is what it is and it either work or it does not.
Given that more often than not the company that makes the heat pump does not make the water pump it is connected to or know anything about the loop their energy usage claims are nothing short of wild guesses.
When people do post their loop temps near the end of the heating season they always seem to be very near 32° or little below not the 55° the sales literature talks so much about.
Given the very high cost of the wells/loops the chance that you will be alive when or if the unit ever saves enough energy to recover its costs seems slim to me.
I know two people who have had to replace their ground source heat pumps. In both cases thousands of dollars were spent for shortly before they were declared dead and replaced.
Walta
It is my experience, down here in the South and SW, that geothermal starts making economic sense when installing in houses greater than 8K ft². If that's the case, they are awesome.
The economics vary between projects. Up here in Zone 6 (Minnesnowda) Running a properly sized ECM pump is often times cheaper than running an ECM blower. Look at your cost per KwH (BTUh) to see where the breakpoint occurs. You need to factor in the cost of drilling wells versus the cost of air sealing and insulation.
I am designing for a Cold climate air to water heat pump with supplementary heat and putting most of the money into air sealing and insulation. But then, I was raised to be a wet head, I.e. hydronics guy.