Heating a pool with an air conditioner

[gonjah]

No, it was about heating the pool.

I just watched it and it sounds like it's both. It does make very good
sense. Apparently it's nothing new.

http://www.thisoldhouse.com/toh/tv/ask-toh/video/0,,20652494,00.html

(3rd scene)

Thanks for posting BTW. It sure gives me something to think about.

 

[trader4]

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

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.

 

[gpsman]

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 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.

 

[gonjah]

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.

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.

 

[recyclebinned]

I won't call you names over it because most folks don't know what's in

the AC/pool heat exchangers. Here's a link for the type heat exchanger

used for pool and marine applications. ^_^



http://www.pexsupply.com/Marine-Swim-Pool-Heat-Exchangers-MPN-Series-5x12-1065000



http://tinyurl.com/a7q9zbc



TDD

Not all heate exchanger are created equal:

http://www.alibaba.com/product-gs/618446493/Copper_Coil_Heat_Exchanger_Solar_Water.html

 

[The Daring Dufas]

Not all heate exchanger are created equal:

http://www.alibaba.com/product-gs/618446493/Copper_Coil_Heat_Exchanger_Solar_Water.html

I looked up the one Derby Dad was posting about and it turned out to be
made of titanium. ^_^

TDD

 

[Oren]

I looked up the one Derby Dad was posting about and it turned out to be
made of titanium. ^_^

TDD

The video even stated that fact.

 

[homeowner]

Ask This Old House showed the installation of a system that captures the
heat from the AC unit to heat a swimming pool. The AC refrigerant line runs
through a coil inside a canister. The pool water runs through the canister
and the heat is extracted.

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......

 

[peace and love]

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......

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.

 

[Existential Angst]

Ask This Old House showed the installation of a system that captures the
heat from the AC unit to heat a swimming pool. The AC refrigerant line
runs
through a coil inside a canister. The pool water runs through the canister
and the heat is extracted.

OK, that's all well and good. Efficient, free heat heat for a pool which
is
shaded by trees and gets very little sun.

Let's think about this. When it's hot out, the AC is running and pool gets
heated. When it's cool out, the AC is not running, so the pool does not
get
heated.

Sure, there's some advantage to heating the pool on a hot day, even into
the hot night. However, on a cool day or cool evening, when the owner
would
really want the pool heated, he's right back where he was before the
system
was installed. Early and late in the season, when it's not hot enough for
the AC to be running for any length of time, there is no heat available
for
the pool - right at the times of the season when you would want it.

Considering that it takes a certified AC tech to capture the refrigerant,
adapt the AC piping and recharge the system, is it really worth installing
one of these systems? I don't have a pool, so I don't know how cold the
water in a shaded pool would be on a day hot enough for the AC to be
running.

After a few days of cool weather, how long would would the AC have to be
running for it to heat the pool to something that would be comfortable?
Yes, I know it depends on the size of the pool and how cool it was. The
one
in the show was a decent sized in ground pool. Is it a matter of a few
hours or would it take all day or longer? I know there's a number of
variables involved...just looking for some idea.

It just seems kind of bass-akwards to only have heat available on hot
days.

You may not have a pool, but I say you're on the right track.
You're right, durintg the times you are most likely to want to heat
the pool, the AC will not be running much. When the AC is running a
lot, you're not likely to need it much to warm
the pool. Here in NJ the AC is running a lot in Jul and Aug,
precisely the time you typically don't need to heat the pool.

Also take a look at the BTUs of a typical pool heater.
I have one here that is gas, 400K BTUs for a 48,000 gal
pool. You can scale that for other sizes. They don't
put 400K btu heaters in for nothing. It takes a hell of
a lot of energy to heat all that water. A 4 ton AC by
comparison is only 48,000 BTUs, an order of magnitude
smaller
====================================================


Wow.... 400K btu's is a lot....
This might be an idear unique to your situration, but why don't you build a
hot-air type heat exchanger for your pool, and just *talk* into it?? I'll
bet your gas bill will drop to zero, and your pool temps will climb to,
like, 110 F.....
On a particularly loquacious day, you might be able to heat your neighbors'
pools as well.....
--
EA







And also a lot of the heat from a pool is quickly lost,
so you can't keep building it up over days.
So, if you have a couple days of putting heat into it
with the AC system, then days where it doesn't heat,
in a day it will be cooled down again. That can be
slowed by using a thermal pool cover, but that is
yet another obvious pain to put up with.

So, yeah, I'd say the whole thing is dumb and
I would not spend a nickel on it.

 

[trader4]

You may not have a pool, but I say you're on the right track.
You're right, durintg the times you are most likely to want to heat
the pool, the AC will not be running much.  When the AC is running a
lot, you're not likely to need it much to warm
the pool.  Here in NJ the AC is running a lot in Jul and Aug,
precisely the time you typically don't need to heat the pool.

Also take a look at the BTUs of a typical pool heater.
I have one here that is gas, 400K BTUs for a 48,000 gal
pool.  You can scale that for other sizes.   They don't
put 400K btu heaters in for nothing.  It takes a hell of
a lot of energy to heat all that water.  A 4 ton AC by
comparison is only 48,000 BTUs, an order of magnitude
smaller
====================================================

Wow....  400K btu's is a lot....
This might be an idear unique to your situration, but why don't you builda
hot-air type heat exchanger for your pool, and just *talk* into it??  I'll
bet your gas bill will drop to zero, and your pool temps will climb to,
like, 110 F.....
On a particularly loquacious day, you might be able to heat your neighbors'
pools as well.....

If you don't have something to contribute, I suggest you
just not post, instead of hurling insults for no reason.

 

[trader4]

I think no matter how you view it it's going to be a real close call.

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

don't know enough about HVAC to understand how it makes the AC more
efficient, but he claims it does.

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.

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.- Hide quoted text -

- Show quoted text -

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.

 

[trader4]

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.

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.

Does it steal money? Maybe. I'd like to see some real stats before I
invested.

Me too. You would think TOH would come back a week
later to show the results.

 

[gonjah]

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.

Yeah. Good points.

 

[Existential Angst]

You may not have a pool, but I say you're on the right track.
You're right, durintg the times you are most likely to want to heat
the pool, the AC will not be running much. When the AC is running a
lot, you're not likely to need it much to warm
the pool. Here in NJ the AC is running a lot in Jul and Aug,
precisely the time you typically don't need to heat the pool.

Also take a look at the BTUs of a typical pool heater.
I have one here that is gas, 400K BTUs for a 48,000 gal
pool. You can scale that for other sizes. They don't
put 400K btu heaters in for nothing. It takes a hell of
a lot of energy to heat all that water. A 4 ton AC by
comparison is only 48,000 BTUs, an order of magnitude
smaller
====================================================

Wow.... 400K btu's is a lot....
This might be an idear unique to your situration, but why don't you build
a
hot-air type heat exchanger for your pool, and just *talk* into it?? I'll
bet your gas bill will drop to zero, and your pool temps will climb to,
like, 110 F.....
On a particularly loquacious day, you might be able to heat your
neighbors'
pools as well.....

If you don't have something to contribute, I suggest you
just not post, instead of hurling insults for no reason.
===========================================================

Well, ahhh, harrumph, I would say that given the numerous *vituperative (and
humorless) insults* you've hurled at me on sundry occasions, there's quite a
bit of historical reason.....
But I just couldn't resist this one.... I'm sure there are a few viewers
buying new keyboards, as we speak.
Even you gotta 'mit, dat WAS a good insult..... My apologies to all....
LOL

Inyway, I've actually come to appreciate your dour know-it-all personna,
cuz, well, at least you DISCUSS shit, unlike those friggin prissy assholes
on rec.woodworking, whose panties are so bunched up, it must be interfering
with their collective bowel function...... goodgawd..... ahm figgerin dat
hypocrite TiredAss is such a pill cuz he has a colostomy, anyway, so he just
bunches his panties for the helluvit....
Plus it seems those assholes seem number/idea-averse.... I couldn't
believe their resistance to just talking about *ideas* re the sawstop -- so
fukn what if wood grain wadn't specifically involved..... **** them.

But hey, dats one bigazz pool you got over there..... Ahm figgering on the
order of 1600 sq ft, 40x40 or equiv....
NJ must tax you up the ass for that thing.
Cain't hide pools anymore.... municipalities now use google earth to catch
people.... hilarious....

To me, pools are like fireplaces -- great in the beginning, but what an
eventual pita I haven't used my fireplace in over 10 years.
I spose if one loves swimming, pools are OK, but even then....

Toward the end of "pool logic" -- and inevitable thread drift -- these
"continuous pools" (the water equivalent of a treadmill) seem like a good
alternative for die-hard swimmers and phys therapy/rehab, a lot less trouble
than a hyooge bonafide pool.
Heh, at least with a water treadmill, google earth won't trigger an
up-the-ass tax event.....

 

[Robert Neville]

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.

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.

 

[Existential Angst]

"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.


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

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.[/QUOTE]

 

[Transition Zone]

"Existential Angst" <[email protected]> fired this volley in



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.

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)?

 

[Transition Zone]

 > 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

 >wall), and run the condensate outside.  The wasted energy also heats
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)?

Oops, didn't read that. You ran the thing with the windows closed.

 

[Existential Angst]

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.

Tried that.... for some reasons the units would ice up. An A/C guy told
me that would be a common problem, forgot what the reason was.
But, if they don't ice up, a useful application of an otherwise old beatup
A/C unit.
Also, if you turn them around in the window during the winter, you have a
heat pump....