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We installed geothermal HP HVAC systems last year (two 3-ton units to replace three SEER 10 old conventional units, two were 2.5 ton and one was 1.5 ton). Couldn't be happier. Besides the power savings (they seem to use about 25% less energy when "on"), they run for a shorter time, have a much higher efficiency, will do both heating and cooling, won't dry the winter air as much as a furnace (I found I no longer need a humidifier), and will handle more square footage with less on time than the old units. They also push a lot more air at the same power level as the old technology fans (SEER 10 units were about 12 years old).
We plan to live here a long time, and those units were getting long in the tooth, so I planned ahead and went with geo. Combined with our 10.5 kW of solar PV on the roof, our total gas plus electric bills are $200-250/mo less than before, on average.
When we talk about electricity uses in geothermal, I think geothermal HVAC systems use only one unit of electricity to move up to five units of cooling or heating from the earth to a building.
When we talk about electricity uses in geothermal, I think geothermal HVAC systems use only one unit of electricity to move up to five units of cooling or heating from the earth to a building.
This "statistic" gets thrown around a lot but has little real world meaning to most of us. In reality it's not as efficient as many people tout, but is still noticeably more efficient than even high end conventional heating and cooling units.
No, the 50 degree liquid from the ground loop is run through an evaporator to transfer energy to a refrigerant liquid to turn it into gas.
That's already a far more complex system than the simple downpipe heat exchanger proposed by the OP.
And therein lies the core reason that geothermal systems are not more popular in the US, because they typically require a larger capital investment than more common systems, with a long payback cycle. In the long run they make sense, but long range planning is not a favorite activity of US homeowners.
I think he was describing how a heat pump can also be used to heat a forced air system. I think he's from Pennsylvania and they tend to be a little biased towards keeping warm rather than keeping cool.
If you are, say, 30 years old and you have the cash or the credit to build your dream berm off the grid and you absolutely know that you will be there forever and don't get too involved in that whole time value of money thing, then it probably does make sense to go with ground loop heat pump, but I think that if you're being really objective in your comparisons you probably recognize that it isn't THAT competitive at the current COI for most people and in most circumstances. Things are moving in the right direction, but there's a long way to go yet.
I think he was describing how a heat pump can also be used to heat a forced air system. I think he's from Pennsylvania and they tend to be a little biased towards keeping warm rather than keeping cool.
If you are, say, 30 years old and you have the cash or the credit to build your dream berm off the grid and you absolutely know that you will be there forever and don't get too involved in that whole time value of money thing, then it probably does make sense to go with ground loop heat pump, but I think that if you're being really objective in your comparisons you probably recognize that it isn't THAT competitive at the current COI for most people and in most circumstances. Things are moving in the right direction, but there's a long way to go yet.
You need to revisit your understanding of finance. Since you can roll the GSHP into your mortgage, it will pay out at any reasonable retail electricity price. It works even better in rural areas where natural gas isn't available as a heating source.
You need to revisit your understanding of finance. Since you can roll the GSHP into your mortgage, it will pay out at any reasonable retail electricity price. It works even better in rural areas where natural gas isn't available as a heating source.
I feel as though there has been a communication breakdown somewhere along the way.
I recognize that all GSHP installations are not equal, however, (I priced this recently) the installation costs in my region (where cooling is the concern and heating is an afterthought) are generally going to be about $5K per tonne and retail electric rates are going to be around $0.11/kwh. Under those conditions, off-grid power generation to feed a >14 SEER conventional system is a better investment for the same cost whether you're rolling into your mortgage with a new build or retrofitting. Whether or not it will eventually pay out doesn't necessarily a good investment make. For illustration, if you want me to invest $25,000 in a start up and you pitch it to me along the lines of "In 15 to 30 years, depending on economic conditions, you will make your money back and the investment will become profitable and you will be well on your way to a 1.15:1 ROI", then I think I would tell you to go pound sand because there are simply too many better things to do with the same money...
Last edited by Cleonidas; 06-20-2014 at 09:49 AM..
I think he was describing how a heat pump can also be used to heat a forced air system. I think he's from Pennsylvania and they tend to be a little biased towards keeping warm rather than keeping cool.
That wasn't the issue. He incorrectly described the process, stating that the liquid from the ground loop (typically water + anti-freeze) is turned into a gas in the evaporator. It isn't. What gets turned into a gas in the evaporator is the liquid refrigerant, which the ground loop liquid heats via a heat exchanger.
Our TOTAL bill is that much. What was your bill before?
Varied from around 250 low end to well over 400 in hot summer months. This is for 4500 square feet with pool running daily even in winter. Combined bill between gas and electric. We both work from home too so the house is kept comfortable at all times.
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