Heating a pool with an air conditioner

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I think those of you that think this is going to make a substantial difference in cooling costs to the house are barking up the wrong tree. It's true if you had the same size condenser that you could get more cooling out of it by using water on the condenser instead of air. But the condenser the AC unit already has consists of a coil and fan that are sufficient and sized so that it brings the refrigerant temp down close to that of the outside ambient air. It does that with an electric fan that probably uses less energy than the pool pump would. If you feel the pressure line where it enters the air handler it's around room temp. A pool in the months when you need AC is going to be around 80F. So, you're not going to drop the refrigerant temp any more than that by passing pool water over it. In other words, I don't see it making a difference.
And the suggestion to use the pool with a heat pump to get heat in the winter is pretty much a non-starter, IMO, too. In the climates where it would make the most impact you have freezing temps. Pools and the existing pool eqpt are not designed to operate in freezing conditions. I guess you could do it in FL, but given the climate, little need for heat, why bother? And as for heating the pool down there, in the months when it would work, they actually are cooling some pools because they get too hot on their own, no?
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wrote:

After posting this, I realized there was one aspect I overlooked. I compared the electricity to run the pool pump with the electricity to run the pool pump. But the electricity used by the pool pump can probably be ignored because the pool pump typically runs 6 or 8 hours a day to filter the pool water anyway. So, it can be filtering while doing the AC.
In which case, I can see the system saving basicly whatever it took to run the fan motor on the AC condenser. Which is something. But the whole thing appears very impractical to me for a variety of reasons. The biggest obstacle being the mismatch between the periods when you need it most and when the AC is actually running the most. For example, here in NJ, when the heating is most useful is late May and June at the beginning of the season and Sept to extend the season for a few weeks. Those times the AC is not running all that much.
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Well you'd only be using the pool on warm days. So makes perfect sense.
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We can add pools to the list of subjects you obviously are clueless about.
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On 12/9/2012 8:33 AM, snipped-for-privacy@optonline.net wrote:

Heck, the only time I have a pool out back of my shack is when it rains. 'course we can put thick plastic in the bed of the pickup and fill it with water. ^_^
TDD
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Via the AC, which is obviously woefully insufficient to heat the standard 16x32 20K gallon pool.
Seems it must be a system auxiliary to a dedicated heater. -----
- gpsman
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No, on this TOH show it was installed as the only heater for a pool in a shaded area. I certainly could be used in conjuction with another pool heater though. But still, IMO, a dumb idea. One of those being, as you say, that the amount of heat it takes to heat a typical inground pool vs the amount of heat available, at the times of year you need it, does not seem to compute.
I'd love to hear a follow up report on how well it works. Funny that they didn't do anything like that.... Like turn it on and see how much if warms the pool over a few days.
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wrote:

I had to view a couple minutes online to see if the pool was in Hawaii, the online version seemed to skip that part. http://video.pbs.org/video/2311120851 /
It seems they need heat in summer, as do we. I suppose if the heat is constantly applied day after day it might eventually provide a few more degrees where a few more makes a big difference between too cold and tolerable, but even that seems unlikely unless some type of super solar blanket is used to keep all that surface area from dissipating the heat.
I don't think that little ~2 gallon heat exchanger is going to win that race unless the ambient air temp. is ~100F 18 hours a day falling to 90 at night. -----
- gpsman
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On 12/9/2012 11:47 AM, gpsman wrote:

I think no matter how you view it it's going to be a real close call. I don't know enough about HVAC to understand how it makes the AC more efficient, but he claims it does.
With my pool, the pool plumbing is on one side of the house and the compressor is on the other making plumbing a real problem. I'd have to dig and make some additional input/outputs or run plumbing all the way to the pump. Doesn't seem to make much sense in my situation. But I am interested in lowering my AC costs. The money would probably be better spent on additional insulation.
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Close? Close to what? Nothing I've seen suggests it's feasible for heating a pool, when and where you need to heat a pool.
I

It eliminates the fan in the condenser unit, using the pool pump instead. The pool needs to be filtered for 6 - 8 hours a day anyway, so that pool pump electricity is already paid for.

I say if it's right next to the pool eqpt, like in the video, it's still nuts. And what does it cost to install that thing? Unless you DIY, you need a pool tech, an HVAC tech, and an electrician. And then let's say the AC system isn't working right. You call an AC tech. They have never seen anything like this. In my experience, you're lucky enough to get one that understands and can correctly diagnose a standard system.
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On 12/10/2012 9:38 AM, snipped-for-privacy@optonline.net wrote:

Yeah. Good points.
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It's also more efficient to move heat to a liquid rather than the air, plus most of the time the water is going to be cooler than the air when the a/c is running, another reason the a/c will be slightly more efficient.
That said, if you are going into this kind of setup thinking it will save you money in heating a pool, you need a refresher course in basic thermodynamics. Then look at what a PITA combo VCR/TVs were and consider what you'd be dealing with with your average HVAC tech.
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The fact that it's more efficient to move heat to a liquid is reflected in the size of the CONDENSER. The existing air one is much LARGE. The replacment pool water one is much smaller. As long as the temp of the refrigerant when it reaches the air handler is the same, you're not gaining anything in efficiency, except the previously noted issue of using the pool pump motor versus the AC condenser motor. And if you feel the pressure line where it enters the air handler, it's already close to ambient. At least mine is and I would hope it is on any relatively modern AC unit.
As to the water being cooler, if the thing is doing what it's intended to do and claimed to be capable of doing, then it should be keeping the pool 80 to 80F. That doesn't sound very much different from average ambient air temp in locations that need pool heating, in the months when they need it most.

Absolutely agree with the last part.
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On Sat, 8 Dec 2012 23:08:36 +0000 (UTC), DerbyDad03

Isn't the purpose of a pool to cool off in hot weather? What's the point in heating it?
Sounds to me like another useless gadget to steal people's money......
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On 12/9/2012 6:26 PM, snipped-for-privacy@home.com wrote:

Sort of. When it's hot out (90+ degrees F) some pools still only get into the high 70's and low 80's depending on the amount of sunlight. My pool, when it's exposed to full sun, doesn't need any help. But, if you watch the video, he says this pool gets little sunlight. Some people want the pool in the high 80's. In that case it might push it up a few degrees. Plus he says it helps the AC, which would be my main concern.
Does it steal money? Maybe. I'd like to see some real stats before I invested. Plus. Your pool pump and condenser would need to be in the same location. That doesn't seem to be real likely unless you built your pool and a/c accordingly. In my case, it's pretty much out-of-the-question.
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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. 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.

Me too. You would think TOH would come back a week later to show the results.
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On Mon, 10 Dec 2012 07:43:07 -0800 (PST), " snipped-for-privacy@optonline.net"

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

savings. 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.
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wrote:

Excellent points. Bottom line, the pool will help the A/C MUCH more than the A/C will help the pool. BUT, it is proly unlikely this could be done economically, at least in a one-off basis.
But, if A/C mfrs would outfit the condensing heat exchanger with a water jacket, so that all's you needed was some fittings, plastic tubing and a small-ish pump, then indeed it would be economical, and likely radically increasing the SEER ratings.
--
EA


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Yeah, but then they wouldn't work with air. There has to be intimate contact between the condensor tubing and the exchange medium.
If they were to outfit them with "Siamese" condensor tubing, so one line carried refrigerant, and the other a liquid exchange medium, AND put fins on the array -- then it would work, but would be quite a bit more expensive.
On a side note: With a little re-wiring of the controls, a large window unit AC makes a dandy monster-scale dehumidifier. Just situate the whole affair inside the conditioned space (instead of through a window or wall), and run the condensate outside. The wasted energy also heats the space (some).
I have dehumidified large industrial drying rooms for cheap that way.
Lloyd
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On Dec 11, 7:06am, "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:

window
the
Does the evaporator still run cold? And if not, does any water condense inside of the unit (as the inside area's air is on its way out)?
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