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Nate Nagel

On 12/12/2012 08:19 AM, wrote:
On Dec 10, 12:38 pm, Vic Smith
wrote:
On Mon, 10 Dec 2012 07:43:07 -0800 (PST), "

wrote:

Think about how it could help the AC. The current coils
and fan in the condesner are perfectly capable of taking
the heated, compressed refrigerant down to close to
ambient temperature. The pool heat exchanger is going
to do the same thing.

"Ambient" pool water temperature normally isn't the same as ambient
air temp.

I never said they were. Only that they are, fairly close.
If this thing works, then it should keep the pool at 80 - 85.
That isn't all that much different than the ambient air
temps when the AC is going to be running. Sure, the pool
could be 65 in May. But then the AC isn't running or
isn't running enough to make any impact anyway.

A pool provides an enormous heat sink, cooling at night,
with evaporative cooling not requiring jumping through EPA hoops.
Water is thousands (WAG) of times more capable of removing heat than
air.

That is reflected in the size of the CONDENSER. The
existing on is sized based on AIR. The pool water one is
sized based on using WATER. So, of course the pool
water one is much smaller. But if the temp of the refrigerant
when it leaves the condenser and returns to the evaporator
in the air handler is the same, then the only thing you've
accomplished from an energy standpoint are replacing
the fan motor with a pump motor. As previously noted,
that is a benefit as long as the pool pump would be
running to filter the water anyway.

And "perfectly capable" doesn't address the difference in time running
to do the same job. Which gets to electrical consumption and
compresser/fan wear.

Yes it does address it, because, again, the refrigerant temp
is still going to be about the same temp when it returns to
the air handler. Whether it got to that temp by a large air
based heat exchanger or a small water based one doesn't
matter, the pool pump motor replacing the fan motor being
the essential difference.

Yeah, it's smaller because water
can take the same heat away with a smaller heat exchanger.
But, at the end of the day, all I see that's saved is the cost
of running the AC condenser fan. Don't know how much
that is in the whole AC scheme, but considering you have
a compressor, big blower in the furnace, I'd be surprised if
it's more than 15% or so.

I've seen estimates that water cooled condensers give 20-50% energy
savings.

Anybody can give you "estimates". I'd like to see real data
on this pool thing. And as I've said, you do get some savings.
It's due to the fact that you no longer have the fan on the
condenser running. Instead you're using the pool pump
motor, which you can assume is paid for by it having to
run for pool filtering, anyway.

It's all in the details - and climate.
In some climates people want their pools chilled.
Barring that, using pool water to cool the condenser is elegant and
efficient if the bottom line works out The main issues are initial
cost and maintenance.
Those are the nuts to crack. It all gets to payback.

Do you have a pool? Pool heater? What size is the pool
and what is the pool heater in BTUs? In my world, there
is no way this computes.

It seems to me that the real advantage of a setup like this would be
that the pool water would act like a "ground loop" and make the air
conditioner more efficient, as the pool's temperature would likely be
less than ambient air on the hottest days when the A/C is likely to be
wanted most. I never did like the idea of using a big box sitting on a
pad trying to shed heat to 100F air on a hot day when you could shed it
deep underground where the temp is less. Simple thermodynamics tells
you which is going to be more efficient. I suspect that you would still
need some auxiliary method of heating the pool water either solar, gas,
what have you, but overall it still seems like a good idea.

nate

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