I am starting from scratch here.
I would like to know what the typical power requirements are for a geothermal system.  I know there will be a couple of amps for a circulating pump, but what about the heat exchanger(?) or anything else that is involved.
The reason for the question is to find out if an "average" solar panel system would generate enough power to run it...?

or should I plan on a 20 to 30 amp breaker anyway?

Way too vague a question...what the heck is an "average" solar system?

Geo systems range in tonnage from 2 to 6, with greatly differing power requirements.

The vague and uncertain nature of your question suggests you need professional contracting assistance...seek it.

I knew the quotation marks were a mistake.
More specifically, if I want to use geothermal for my radiant floor heat only - what part of that system would be using electricity, besides the circulating pump?
If the layman's nature of this question is too vague I apologize .

The first thing you have to know is your homes heat loss/gain to determine what size heat pump is needed. This is calculated using ACCA Manual J.

The heat pump compressor uses the bulk of the electricity in a geothermal HVAC system.

I pulled up the electrical data for Climatemaster Tranquility 27 series geothermal heat pumps as an example as follows:

2 Ton (26K BTU) = 10.3 compressor amps, = 4.0 loop pump amps, = 3.9 fan amps
3 Ton (38K BTU) = 16.7 compressor amps, = 4.0 loop pump amps, = 3.9 fan amps
4 Ton (49K BTU) = 21.2 compressor amps, = 4.0 loop pump amps, = 6.9 fan amps
5 Ton (64K BTU) = 25.6 compressor amps, = 4.0 loop pump amps, = 6.9 fan amps
6 Ton (72K BTU) = 27.2 compressor amps, = 4.0 loop pump amps, = 6.9 fan amps

These are running amp ratings at rated voltage of 230 VAC.

The 2 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 22A/30A
The 3 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 30A/45A
The 4 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 38A/50A
The 5 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 44A/60A
The 6 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 46A/70A

If you were using a unit for radiant floor heat only, you would replace the fan amps listed above with the amp load for the radiant heat circulating pump which would likely be similar to the amps used for the fan. As an example using the 3 ton heat pump specs above, total system running load would be 16.7A + 4.0A + 3.9A = 24.6A @ 230 VAC = 5.7 KW.

Note that the above running loads do not take into consideration the starting amps required for the compressor. The 3 ton compressor above has a starting load of 82 Amps. This can be significantly reduced if your compressor has soft start capability.

Posted By arkie6 on 31 Dec 2012 02:46 PM
The first thing you have to know is your homes heat loss/gain to determine what size heat pump is needed. This is calculated using ACCA Manual J.

The heat pump compressor uses the bulk of the electricity in a geothermal HVAC system.

I pulled up the electrical data for Climatemaster Tranquility 27 series geothermal heat pumps as an example as follows:

2 Ton (26K BTU) = 10.3 compressor amps, = 4.0 loop pump amps, = 3.9 fan amps
3 Ton (38K BTU) = 16.7 compressor amps, = 4.0 loop pump amps, = 3.9 fan amps
4 Ton (49K BTU) = 21.2 compressor amps, = 4.0 loop pump amps, = 6.9 fan amps
5 Ton (64K BTU) = 25.6 compressor amps, = 4.0 loop pump amps, = 6.9 fan amps
6 Ton (72K BTU) = 27.2 compressor amps, = 4.0 loop pump amps, = 6.9 fan amps

These are running amp ratings at rated voltage of 230 VAC.

The 2 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 22A/30A
The 3 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 30A/45A
The 4 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 38A/50A
The 5 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 44A/60A
The 6 ton unit requires a circuit wiring/breaker/fuse rated MIN/MAX of 46A/70A

If you were using a unit for radiant floor heat only, you would replace the fan amps listed above with the amp load for the radiant heat circulating pump which would likely be similar to the amps used for the fan. As an example using the 3 ton heat pump specs above, total system running load would be 16.7A + 4.0A + 3.9A = 24.6A @ 230 VAC = 5.7 KW.

Note that the above running loads do not take into consideration the starting amps required for the compressor. The 3 ton compressor above has a starting load of 82 Amps. This can be significantly reduced if your compressor has soft start capability.

However, those numbers are under the worst conditions, with relatively inefficient circulation pumps.
A good rule of thumb is 1KW/ton, so a 3 ton system would draw about 2 KW in 1st and about 3 KW in 2nd stage. Below are 3 examples with live streaming electrical data while in operation. It is for circulation pumps, fan and compressor.
http://welserver.com/WEL0477/
http://welserver.com/WEL0603/
http://welserver.com/WEL0396/

WEL0396 is unique since it has both a wattsmeter and an amp sensor for calibration purposes.

thanks very much for the informative and succinct answer(s).
I am glad to have found this forum and learned as much as I have in so short a time.
I live in an area where there are not a lot of choices when is comes to geothermal installers/contractors and learning the vocabulary
seems to be a good idea.

If you are going geo and electric hot water with electric auxiliary, I would figure an "average" of 50-100 additional amps of load to the homes electrical infrastructure. The numbers listed above do not reflect start-up requirements, auxiliary heat (if employed) etc.
So no I don't expect the "average solar panel" to run it or a 20-30 amp breaker either.
Good luck,
j

Joe
Thank you for the response. It seems that a conventional power source makes more sense, especially when there is a budget to consider.
I guess I need to focus on figuring out the return on the investment in geo vs fossil.

thanks

Absolutly. The first step however in that study is understanding your requirements. The "scratch" you need to start from is heat loss/gain. Attack it first with reduction strategies (better insulation) and then have contractors model conditioning strategies- fossil, air source and ground source heat pumps. Then you will know what makes the most sense.

Is there a systems comparison out there ? as in, Water Furnace vs ClimateMaster vs etc, etc
The long term payback on any system seems to hinge on how reliable / problem free they are.... this would mean that a parts and labor
warranty would factor in quite a bit, one would think?

They are pretty much comparable. We started to swing a bit towards Waterfurnace lately, they are pushing the envelope a bit more with new products.

I have an 8.1 kW solar PV system (grid tied, batteryless) along with a geo HVAC system.  You can look at the second chart (InstantaneousSolarPower) at http://www.welserver.com/WEL0043/ to see how well the geo HVAC system fits within this fairly large solar PV system (it doesn't).

I run anywhere between 2 and 5 tons total.  You can see that for situations like right now, where it's bright sunshine outside, the load on the home for the geo system (almost all of the 'spikes' you see) is within what's being generated.  But by no means is the solar PV system big enough for inrush current surge at geo system startup, and, it's not adequate for steady state operation on cloudy days.

The cost of putting in batteries, and putting in a larger solar PV system to accommodate the geo HVAC system, is just too expensive for me to consider.

Best regards,

Bill

Posted By bugzee on 05 Jan 2013 06:57 AM
Is there a systems comparison out there ? as in, Water Furnace vs ClimateMaster vs etc, etc
The long term payback on any system seems to hinge on how reliable / problem free they are.... this would mean that a parts and labor
warranty would factor in quite a bit, one would think?

Dealer matters most. If you buy the best unit from the worst dealer you will likely be less happy than if your buy the worst unit from the best dealer. WF has the first variable on the market, while CM keeps winning design awards and moves forward with communicating systems. Neither manufacturer will be there for you if the equipment breaks. You need a good dealer in your corner. j