Geothermal Heat Pump with Single Well (Pump and Dump)

[Cary Austin]

Open loop heat pump and house supplied from a single well pump.

[Electron Partier]

I've always wanted a Geothermal System, but the ground loop for 5 Tons of cooling (in Desert), is not cheap.

This is interesting, the Air conditioning (we're Cool-Bound in Desert) system transfers the heat to the water, and you dump the water?

Maybe this could work for me.

My new property I'm developing in Pahrump Nevada will have a water well, that water well will have Water rights associated with it for beneficial use. Beneficial use is defined in Nevada as having a pond or lake. So I have pump 1 to 2 acre feet of water per year.

Since I have to pump that water anyway, putting that water into my pond/lake/beach, would work as an Open Loop system. In Winter I simply steal the heat from the water, and dump the water into my pond. The frogs will love that?

Am I thinking clearly?

-R

[Cary Austin]

I've always wanted a Geothermal System, but the ground loop for 5 Tons of cooling (in Desert), is not cheap.

This is interesting, the Air conditioning (we're Cool-Bound in Desert) system transfers the heat to the water, and you dump the water?

Maybe this could work for me.

My new property I'm developing in Pahrump Nevada will have a water well, that water well will have Water rights associated with it for beneficial use. Beneficial use is defined in Nevada as having a pond or lake. So I have pump 1 to 2 acre feet of water per year.

Since I have to pump that water anyway, putting that water into my pond/lake/beach, would work as an Open Loop system. In Winter I simply steal the heat from the water, and dump the water into my pond. The frogs will love that?

Am I thinking clearly?

-R

Yes!  I have a system like that.  I have a pond for livestock and wildlife.  My well only produces about 4 GPM, so I have to keep it running at 3 GPM all the time (24/7) to keep the pond level up.  It is a shallow well and I only have to use a 1/3HP pump,  so it only cost me about $50 a month to operate.  I built a house fairly close by and decided to use the free heat or cool from this 24/7 flow of water to heat and cool the house.  The house is actually 3500' from the well.  So I ran 7,000' of 1 1/2" poly all the way to the house and back to the pond.  Not only does this water heat and cool the house, but it also supplies the house with fresh water.  Since I only had 3-4 GPM to work with, I could only install a 3 ton heat pump.  This was a little undersized for the house, so I also went with a lot of extra insulation.

This system has worked great for over ten years now.  That little pump has not shut off in over 12 years, except for the occasional power outage.  The well will actually produce up to 10 GPM for short periods of time, so it supplies the water to the house just fine as well.

Just to make this even more confusing, I supply the house from the discharge of the heat pump.  The water comes into the house about 15 degrees warmer or cooler, depending on the time of year and whether the heater or AC is being used.  But it keeps me from having to supply enough water for the heat pump plus the house separately.  When the house is using water, there are times when the heat pump has 10 GPM flow instead of 4 GPM flow, but that just makes the heat pump work more efficiently. 

So this little 3 GPM pump and well supplies all the water for heating and cooling my house, plus has a de-superheater that gives me free hot water.  Then the water leaves this house and goes by a barn and an additional (mother in law house).  On it's way back to the pond it passes my garden which is also irrigated from this water.  I figure I am using this same water about 6 different ways before it dumps the excess back to the pond for the animals.  I think it would be very hard to beat the efficiency of this system as far as electrical consumption and water preservation are concerned.

[TKB4]

I am intrigued by your use of the cal-val valve which appears to act as a pressure relief valve.  So to keep the whole system (meaning your house, the barn/garden and the mother-in-law house) it seems you would have to install the class-val valve after the last pressurized use and before the pond or in other words between the mother-in-law house and the pond .  Is this correct?

If you were not supplying pressurized water for the other uses I assume that it would be more efficient to use the two supply system you have a link for in another post where you supply high psi to house such as 50 psi with jet pump and sidekick and 20 psi to the heat pump via a second CSV.

I believe you are supplying the 50 psi to the heat pump because you are also using the higher pressurized water for the other uses which makes it much more economical in your situation.  It also seems that if you wanted to have a water source heat pump at the mother-in-law house you could also do that even though the temperature of the  water exiting the first heat pump system would have risen or fallen about 15 degrees or so and seem unusable one could possibly use looped piping between the first and second house to act like a closed loop geothermal does to condition the water used by first house prior to entering the second house .  I realize the resistance of any additional piping required if any may be too much to maintain pressure to the second home but this could be overcome by a booster pump if needed.  I also realize the pipe you are using may not be most efficient at heat exchange with the soil.  Just an idea mostly theoretical.  Somehow I believe you may have already considered this.

It is interesting to think of a series of homes ( maybe 4 or so) connected in a similar manner on relatively equal elevation connected in this manner all using water from a sufficiently sized and powered deep well for their water and conditioning needs.

[Cary Austin]

Yeah the modulating pressure relief valve is at the pond.  However, it could be anywhere after the mother-in-law house or the last tee in the water line.  The mother-in-law house is 1200' from the first house.  The water has not had time to cool or warm as needed before it gets there.  I have considered adding a big loop with a couple thousand more feet before it gets there, which would cool or warm it enough to make a heat pump at the second house work.  With such a small flow rate the 1.5" pipe has almost no friction loss, so it wouldn't hurt anything, and wouldn't need a booster pump.  Might not even need the loop if I had made the ditch deeper.  With such a long line the water warms or cools to the ground temp anyway.  I should have buried the lines as deep as they buy the loops, but it still works.

If my well was deeper I would use two pumps to make it more efficient.  But at 47' the 1/3HP submersible will supply the 50 PSI, so I don't need a booster.  I can't get any smaller pump than 1/3HP anyway.  But anytime you can use a smaller pump in the well the booster or two pump system will save considerable energy.

[TKB4]

Thanks for reply exactly what I thought and exactly how I would do it.  I believe for closed loop buried to correct depth generally 600 feet of poly loop per ton more or less depending on soil moisture and location etc and the correct wall thickness of polypipe etc for efficient exchange. So you could do about 2 ton unit with 1200 feet.  Certainly worth thinking about especially if current unit in mother-in-law house bites the dust.