Geo Thermal off-grid

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SolarLurker
SolarLurker Solar Expert Posts: 122 ✭✭
in Off Grid Solar & Battery Systems #1
I did a search and did not find the answer to my question.

I am looking at installing a 4 ton geothermal system ( I gave up on the Freewatt Plus).

The dealer is recommending a unit that will replace my air source central air and dump the extra heat in my pool during summer. During the winter the unit will heat my finished basement. The installer intends to install solar thermal panels.

As far I can tell the unit will use 3500 at draw, what I can not figure out is how much power I can expect to use during a winter day or month.

I have a 11.61kw PV system, I use about 800kw a month currently, I have two 5k sunny islands backing up a 60 amp sub panel that includes the fridge, freezer, well pump, and other necessities.

If I installed more PV would it be feasible to back up the geothermal for 24 hours?
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    Re: Geo Thermal off-grid

    What is your location, will pulling heat out of your pool, turn it into a giant ice cube ?

    Will the solar thermal panels directly heat your house, or a thermal transfer tank for the geothermal ? What about pre-heating for your domestic hot water ?
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #3
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    Re: Geo Thermal off-grid

    3500 watts sound high for a GeoThermal unit, My SEER 15 3 ton pulls 2400-2700 watts in the Florida ( Air )

    Geo units should be +20 SEER or better. Also, you can't use a pool for the Sink or Source because of the chemicals, you would need an exchanger that can handle chlorine

    GEO = Ground based, not swimming pool based
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  • SolarLurker
    SolarLurker Solar Expert Posts: 122 ✭✭
    #4
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    Re: Geo Thermal off-grid

    I was not clear in my first post, I am looking into a Geothermal unit with inground loops.

    During cooling season cool refrigerant will go to my air handler, just like it does with my central air unit, the heated refrigerant returning from the air handler will dumped into a transfer tank (to be used by the pool, and possible to preheat domestic water).

    During winter months the unit would only heat the basement, there would be no need for poop heating.
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  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    #5
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    Re: Geo Thermal off-grid

    GeoThermal units are single units, they are not split like air based heat pumps. What your describing is a desuperheater which is used to heat hot water, again this is for air based heat pumps

    everything you have described is a generic air based heatpump, not Geothermal
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  • SolarLurker
    SolarLurker Solar Expert Posts: 122 ✭✭
    #6
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    Re: Geo Thermal off-grid

    waterfurnace makes a split Geothermal unit.
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  • russ
    russ Solar Expert Posts: 593 ✭✭
    #7
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    Re: Geo Thermal off-grid

    This is really a 'ground source heat pump' (GSHP) sometimes called ground linked or ground coupled. It is not geothermal - that term refers to hot water from down below.

    You can get the same de-superheater for making hot sink water with a GSHP that you can an ASHP.

    GSHP can provide either warm air or warm water - whichever system you buy.

    İf you are located where an ASHP (air source heat pump) will function efficiently - meaning not in North Dakota - they are far more cost effective than a GSHP. The cost of the ground loops or wells and associated piping is very significant. The additional savings offered by a GSHP over an ASHP are small while the cost differences are great.

    The water loop that goes through the pipes in the ground has to be separated from the water to be consumed by a heat exchanger in all cases. The last thing you want is poor quality water going through the heat pump - it will ruin the refrigerant to water heat exchanger there.
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