geothermal energy

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jahilliard

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what all can anyone tell me about geothermal energy systems? how hard are the systems to install? where and for what reasons are they popular? best used in commercial or resi situations?, etc. I can search google and have but I would like responses from contractors and tradesman actually installing, testing, selling, etc. the systems, thanks to all that respond!
 
jahilliard said:
what all can anyone tell me about geothermal energy systems?
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They transfer heat, just like any other climate system.


jahilliard said:
how hard are the systems to install?
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I'd leave that to the HVAC contractor. Wiring them is just like any other equipment... look at nameplate, go from there.

jahilliard said:
where and for what reasons are they popular? best used in commercial or resi situations?, etc.
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Long-term energy savings.

jahilliard said:
best used in commercial or resi situations?, etc.
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Either one, just depends on whether the owner wants to pay for it up front.
 
A geothermal system is no different than any ordinary heat pump.

Instead of a refrigerant to air heat exchanger for the condensing coil, it has a refrigerant to groundwater loop heat exchanger for the condensing coil. No special hocus-pocus.
 
080923-1919 EST

My question is this:

If you have a horizontal ground loop about 8 ft deep what happens to the average temperature of the soil, assume clay loam, as you progress thru the winter, and also thru the summer?

My guess is that the thermal resistance of the soil is sufficiently high that there will be a gradual cooling during the winter and possible freezing of the ground loop soil.

Anybody have specific information on this?

.
 
gar said:
080923-1919 EST

My question is this:

If you have a horizontal ground loop about 8 ft deep what happens to the average temperature of the soil, assume clay loam, as you progress thru the winter, and also thru the summer?

My guess is that the thermal resistance of the soil is sufficiently high that there will be a gradual cooling during the winter and possible freezing of the ground loop soil.

Anybody have specific information on this?

.
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We're Sparkys, not Tinners.:cool:
 
We are wiring a remodel that is having a geothermal system installed. They are using an electric hot water tank to make up the difference for the water that comes from the geothermal well. (bad idea in my opinion, but oh well....) Also, both air handlers require electric emergency heat. And the heat pumps themselves require power. So electrically there are a bunch of big circuits that need to be installed.
 
peter d said:
We are wiring a remodel that is having a geothermal system installed. They are using an electric hot water tank to make up the difference for the water that comes from the geothermal well. (bad idea in my opinion, but oh well....) Also, both air handlers require electric emergency heat. And the heat pumps themselves require power. So electrically there are a bunch of big circuits that need to be installed.
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The last sentence is all I would worry about.
 
480sparky said:
The last sentence is all I would worry about.
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Right. Honest to God, it's no different than wiring any other air conditioner or heat pump, save for the fact that the condensing unit (compressor unit) is normally indoors. Sometimes in the same cabinet with the air handler, depending on brand. The only thing extra inside these things is a pump for the water loop, but that's all handled by the dataplate. Read the dataplate and wire accordingly. The thermostat connections are identical to any other air conditioner or heat pump.
 
080923-1933 EST

480sparky:

It has nothing to do with Tinners. It is all about efficiency. To have an efficient system the ground temperature needs to be high in the winter and low in the summer.

The thermal capacity of the soil near the earth coil alone with its water content is not sufficient to supply the number of BTUs required for an entire winter. Therefore, thermal resistance to soil deeper down is of great importance.

.
 
gar said:
080923-1919 EST

My question is this:

If you have a horizontal ground loop about 8 ft deep what happens to the average temperature of the soil, assume clay loam, as you progress thru the winter, and also thru the summer?
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That would depend on the length of the loop, one would hope the designers of the system take all factors into consideration.:)
 
gar said:
080923-1933 EST

480sparky:

It has nothing to do with Tinners. It is all about efficiency. To have an efficient system the ground temperature needs to be high in the winter and low in the summer.

The thermal capacity of the soil near the earth coil alone with its water content is not sufficient to supply the number of BTUs required for an entire winter. Therefore, thermal resistance to soil deeper down is of great importance.

.
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Don't get me wrong, but this isn't exactly the field of extertise for most folks here. The only thing we have to do with heat is conductor derating.
 
gar said:
080923-1933 EST

480sparky:

It has nothing to do with Tinners. It is all about efficiency. To have an efficient system the ground temperature needs to be high in the winter and low in the summer.

The thermal capacity of the soil near the earth coil alone with its water content is not sufficient to supply the number of BTUs required for an entire winter. Therefore, thermal resistance to soil deeper down is of great importance.

.
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Were you thinking that the engineers haven't taken that into account?

There's darned few horizontal systems here above the Mason-Dixon. Takes up too much real estate. They're pretty much all well loops. The supply side generally reads 55 degrees, plus or minus a few degrees, any time of the year.
 
mdshunk said:
Were you thinking that the engineers haven't taken that into account?

There's darned few horizontal systems here above the Mason-Dixon. Takes up too much real estate. They're pretty much all well loops. The supply side generally reads 55 degrees, plus or minus a few degrees, any time of the year.
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Which for these parts (up nort) geothermal makes great sense in the summer...but in the winter.....not so much.
 
OK I will not bother repeating what everyone else has said other than they are no different electrically than a standard heat pump unit. But I will speak a little about efficiency and power consumption.

First for a commercial operation like a school where they have a lot of land to use horizontal loops, big energy savings will be incurred.

However when you have to drill wells (small lot) for a vertical loop is where the line gets blurred and could be a waist of money both up front installation cost and operating cost. If your water table is deep requiring deep wells, each well can cost several thousand dollars to drill. Basically you need 1 well for every ton of cooling. But here is the point I am trying to make. If the wells are say 400 feet deep, and you have five of them for a 5-ton unit, it takes a lot of horsepower to pump water that deep and back up. Well you guessed it all the cooling efficiency savings in power is lost pumping water deep into the earth.
 
gar said:
080923-1919 EST

My question is this:

If you have a horizontal ground loop about 8 ft deep what happens to the average temperature of the soil, assume clay loam, as you progress thru the winter, and also thru the summer?

My guess is that the thermal resistance of the soil is sufficiently high that there will be a gradual cooling during the winter and possible freezing of the ground loop soil.

Anybody have specific information on this?

.
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I would imagine that they go below the frost line
 
steelersman said:
I would imagine that they go below the frost line
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Of the very few horizontal systems I've seen go in around here, they go way deeper than that. The crawler loader is completely below grade level by a good bit. Probably 10 or 12 feet deep, from what I've seen.
 
peter d said:
Which for these parts (up nort) geothermal makes great sense in the summer...but in the winter.....not so much.
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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.
 
080927-0817 EST

dereckbc:

Whether you have a deep vertical loop or a horizontal one does not make much difference in the pumping power required. In the vertical closed loop system there is one column counterbalancing the other and the pumping losses are friction the same as in a horizontal system. The vertical system provides a better heat transfer means from the diffuse source of energy.

The vertical system is like two weights attached to the ends of a string and hung over a pulley. Very little power to move up and down.

An open system that pumps water from a deep source does require a lot of pump power, and some place to put that water after heat is extracted.

.
 
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