geothermal energy

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These things make sense in very limited cases because often the upfront costs dwarf whatever energy savings there are long term.

You have to match the need to the circumstances.

IMO, it makes no sense to spend $15,000 extra on an HVAC system to save $500 a year in energy costs.
 
iwire said:
There has to be some truth to it.

Historically heat pumps do very poorly where Pete and I live.
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Yes, air-to-air units. I was referring to ground-loop systems.
 
LarryFine said:
Not true at all. 55 degrees is plenty warm enough for a heat-pump to extract heat from, especially when you consider the density of earth is so much greater than air.

There is also another method of horizontal looping where they dig a deep vertical trench and install the tubing in overlapping loops, which provides many feet of tube per foot of trench.
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You dont live up hear do you? :D
 
iwire said:
There has to be some truth to it.

Historically heat pumps do very poorly where Pete and I live.
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Check this out, made in Maine, air to air, works to -30f

http://www.gotohallowell.com/

UMaine has studied ground loops, for our climate you have to freeze the ground to get the needed heat out. Phase change is alot of energy
 
080927-2134 EST

Following is some information on my needs:

For the cold months of the calendar year 2007 I used 1621 CCF of natural gas. At 102,800 BTU per CCF (100 cubic feet) I used about 160,000,000 BTU.

If I had a tank of water 40 X 40 X 160 feet = 256,000 cubic feet that started at 55 deg F in the fall, then a 10 deg F drop in temperature would supply 256,000 * 62.4 * 10 = about 160,000,000 BTU.

My ground is not that saturated with water. Thus, I would have to have substantial thermal contact with a large area and there would have to be good thermal conductivity from deeper in the earth. That is why I ask in an earlier post what happens to the earth temperature in the general area of the heat transfer coils.

Not all of my BTUs would come from the water and my actual BTU need would be less because my current furnaces are about 70% efficient. Some of the BTUs would come from the AC input.

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around here it used to be somewhat common for farmers to run loops of copper tubing in their stock ponds and pump water through them for cooling. nothing fancy, but pretty cheap. the bottom of a 20 foot deep stock pond stays fairly cool.

these days i would bet the cost of copper tubing would prevent such a scheme.
 
it depends on where you live, cost of different sources of energy, and wether ground loop is required to determine if this type of heating is for you. I live in a place that has one of the lowest electric rates in the country - in fact there are many homes here heated with electric resistance heat and usually cost less to heat than with gas or oil. Geothermal uses even less energy.
Energy usage with geothermal is one of, if not the most effecient systems available as far as amount of heat output per unit of energy input. Another benefit that is not always mentioned is the fact that when you are using your heat pump for cooling most geothermal units also have a hot water generation circuit run through the heat exchanger to allow the heat you are trying to remove from your home to be dumped into your water heater and therefore use less energy heating water - this hot water energy is virtually free as long as you dont use the heat faster than it is created.

I installed a geothermal system when I built my new home four years ago and am very happy with it. I have most of the pros and very few cons working for me for using this system. I have an open loop system. This does not require installing ground loops or additional wells or any of the expensive ways of obtaining a heat source. Water is plentiful here and dumping it on the ground is not a problem after it passes through the system because I have no neighbors nearby and the soil is so sandy that it is absorbed fairly quickly.
I needed a well for domestic water, so that is an expense that was going to happen anyway. The only install expense that I really had that I would not have had with an air to air heat pump was installing the water discharge line
(plus I also had a sill cock installed so if I wish, I can run discharge water on my lawn which needs a lot of water since the soil is very sandy)

My electric bill is the only energy bill I have and it is lower than what I had before in a smaller home with gas heating system.

this system does have electric resistance back up heat as was posted by others as a concern, but with 55 degree constant heat source is almost never needed. I usually don't even turn on the breakers supplying the backup heat to insure it does not run, if you turn the thermostat up more than a couple degrees it will run to try to catch up faster. The only time I have turned on the breakers for backup heat was when there was problems with the water valve and I did not have any other choice.

This system is not for everyone, as I mentioned before, what it takes to get your heat source is the determining factor. If I did not live outside city limits here it would be completely different, drilling a well in town may not be allowed in some cases, and city water would be too expensive to use for this purpose.
 
I would also like to mention that an advantage over an air to air heat pump is the fact that the heat source is constant, when the outside temperature is minus 20 degrees the air to air is probably not going to move enough heat to keep up with the demand, but the geothermal still moves the same amount of heat as it does even if the temperature were 60 degrees, or at least fairly close to the same.

We had a major ice storm a couple years ago that left us without power for 10 days, There is no way my 8000 watt generator was going to heat my home with the 15kw of backup heat , I even tried to run just 5kw for a while with little progress in keeping up with heating demand, but it heated the house just fine using the heat pump which operated somewhere around 1500 watts maybe plus the well that maybe draws around 2000 - but does not run constantly. This roughly 3500 watts of power consumption gives off much more heat than the 5000 watt resistance heat does.
 
kwireds experience with open or closed loop heatpumps is very similar to what most of the users around here seem to have with the newer units. Add a constant pressure pump and things just get better. HVAC tell me about a 10 year payback time. The better units put out about 4 times the heat per watt.
 
iwire said:
So they claim.....

In reality I have never seen any one in this area satisfied with a heat pump system.

As stick points out the fact they all require back up heat of some sort is pretty telling.
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This system is brand new and it must be somewhat different as they are in process of getting a patent?, I don't know anyone who has one so I'm not sure whether its bull or not.

Another Maine company has something similar
http://www.nyletherm.com/spaceheating.htm.

I'm using one of Nyles heat pumps to heat my hot water, it definitely works as advertised
http://www.nyletherm.com/waterheating.htm


I built on to my house a few years ago, I insulated the walls to R42 and ceilings to R54. In my opinion one is better off insulating to the extreme than they are spending mass quanities of money on a geothermal system.
 
gar said:
080927-2129 EST

wallyworld:

Your reference provided no useful technical information.

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Sorry Gar, wish I had something usefull for you. It was one experiment a professor at UMaine did. He buried black plastic pipe, filled it with a glycol solution and ran a heat pump off it. I looked to see if I could find the paper but it was a long time ago
 
080928-0936 EST

wallyworld:

When I encounter an ad with testimonials and no valid useful technical information, then that company and ad are immeadiately suspect.

A patent means nothing in terms of the value of a product to you, however, it may mean a lot to the owner of the patent.

What is important to you as an owner of a heat pump system is long term costs of the equipment, reliability, and efficiency. What is your total equipment life time cost vs that of some other heating and cooling system? That is what you want to know.

The following is a somewhat useful reference. I do not believe from a quick reading that any comparison was made relative to natural gas. I think all savings were a comparison to resistive electric heat.

http://www.oee.nrcan.gc.ca/publications/infosource/pub/home/heating-heat-pump/booklet.pdf

.
 
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