Using swimming pool as water source for heat pump AC?

[motoguy128]

I'm pretty sure you don't want to mix copper with pool chemicals. I'd use a standard water source heatpump, but have a closed water loop to a stainless steel heat exchanger designed for pool water use. Make sure you get the pump sized correctly for the required flow rate on the heat pump.

The only problem is that water temps will get into the 80's in the summer on the pool. Your effciency and capacity will be reduced a little by late summer.

The energy required to operate the pool feature for added evaporative cooling will consume a fair amount of electricity.

[dbooksta]

The only problem is that water temps will get into the 80's in the summer on the pool. Your effciency and capacity will be reduced a little by late summer.

Let's assume it gets as bad as some have suggested: Isn't it still more efficient to heat exchange with 100F water than with 80F air?

The energy required to operate the pool feature for added evaporative cooling will consume a fair amount of electricity.

The "evaporative feature" can just be a redirect of the filter pump returns to spray water through the air instead of under the surface. Pools have to run that pump for hours a day regardless of how it discharges.

[GoofBall]

I'm pretty sure you don't want to mix copper with pool chemicals.

This is a fresh-water (not salt) pool. Yes, there will be green copper problems if the pH gets too low (acidic), but only if the pool is neglected and falls far from the proper pH range. Other than that, what is the issue? Does chlorine attack copper?

I'd use a standard water source heatpump, but have a closed water loop to a stainless steel heat exchanger designed for pool water use. Make sure you get the pump sized correctly for the required flow rate on the heat pump.

Alas, buying a new heatpump is not in the budget

The only problem is that water temps will get into the 80's in the summer on the pool. Your effciency and capacity will be reduced a little by late summer.

In the middle of the day the air temperature will often far exceed 90F, and heatpumps don't complain about that. So using 80F poolwater instead of 90F air will help the heatpump's COP, right at the time when the AC is on the most.

The energy required to operate the pool feature for added evaporative cooling will consume a fair amount of electricity.

Like I said, I'm pretty sure overheating the pool is not in the cards for my climate.
And like dbooksta says, the waterpump is gonna be running anyway; if aeration is needed, you can build a nice waterfall or something into your pool.

3 Tons of AC: produces about 13kW of heat output.
200,000BTU pool heater: produces about 58kW. (4.5x more).
Obviously neither the AC nor the pool heater will have 100% duty cycle.

[beenthere]

Let's assume it gets as bad as some have suggested: Isn't it still more efficient to heat exchange with 100F water than with 80F air?

No, its not.

[GoofBall]

Quote:
Let's assume it gets as bad as some have suggested: Isn't it still more efficient to heat exchange with 100F water than with 80F air?

No, its not.

Aye, the COP (efficiency) depends on the "lift" - the temperature difference between indoors and outdoors. If you want 75F indoors: 80F outdoors requires only 5R(Rankin) of lift. But 100F outdoors requires 25R of lift, with a corresponding drop in efficiency.

[Six]

Man what Geo guys wont do to find a water source.

No in ground, above ground pool, septic system, bird bath or muddy puddle is safe.

Sooner or later someone's going to run a stick of copper through it and yell " EFFECIENCY " !

I was thinking about the pool side of the experiment. We have a lot down here in Houston.

They can go south quick AND everyone is installing salt now anyway. What if you happens when you have to respray the thing ? Or just clean the bottom ?

[Juan Madera]

Add a desuperheater between the compressor and condenser on the gas side of an air-to-air HP or A/C, and let it dump heat into the pool when the circ pump is running. Nice in cooler climates, but in desert southwest may overheat the pool, so a way to bypass if high temps are reached might be a necessity.

[GoofBall]

Has anyone actually witnessed a residential pool-sourced A/C overheat an average 16x32x8' pool? I have no facts, but I just can't see it happening - too many square feet of dissipation area, and too few kW injected into the pool. Plus you guys in the hottest driest Arizona desert have the most evaporative cooling effect.

Maybe you guys are Olympic-Michael-Phelps-types and any pool over 68F is too bloody hot....

[GoofBall]

What if you happens when you have to respray the thing ? Or just clean the bottom ?

I assume your question is "what happens when you turn off the pool waterpump?"
In my proposal the original condensor is still installed and ready for action - just flick on the power switch to the condensor fan, and you're back to the original old-fashioned low-efficiency setup.

[GoofBall]

Add a desuperheater between the compressor and condenser on the gas side of an air-to-air HP or A/C, and let it dump heat into the pool when the circ pump is running.

Excuse my ignorance, can you explain a desuperheater? I googled, but all I found was a rudimentary/obvious setup for injecting cold water into a steam line.

[steveoo]

A pond or stream would work.

[motoguy128]

Chlorine and copper at the levels used in a pool do not mix. It will undergo slow corrosion... meaning those thin wall tubes won't last long.

[Juan Madera]

Excuse my ignorance, can you explain a desuperheater? I googled, but all I found was a rudimentary/obvious setup for injecting cold water into a steam line.

A desuperheater takes the hi temp, hi pressure gas directly from the compressor and uses the heat to (typically) heat domestic hot water in a commercial refrigeration rack system. As the water temp is generally 140F or more, the refrigerant does not condense, just lose superheat and increase the efficiency of the condenser. Win-win all the way round. In a pool application the refrigerant would condense and do so at a lower temp than an air side condenser. Might even have to worry about too low of a head pressure!

Grocery stores with a meat department tend to use a lot of hot water and this is essentially free heat from the refrigeration and A/C system, so you will generally see a desuperheater water tank there.

Nordyne was selling a system for residential installations a few years back that did the same thing on a smaller scale. Some of the GSHP manufacturers like Water Furnace offer this an an option as well.

Found a link for you at: http://www.energysavers.gov/your_hom.../mytopic=12840

and the paragraph follows:

Homeowners primarily install geothermal heat pumps—which draw heat from the ground during the winter and from the indoor air during the summer—for heating and cooling their homes. For water heating, you can add a desuperheater to a geothermal heat pump system. A desuperheater is a small, auxiliary heat exchanger that uses superheated gases from the heat pump's compressor to heat water. This hot water then circulates through a pipe to the home's storage water heater tank.

Hope this helps!