[RE-wrenches] Heat Exchangers Topic for Swimming Pools

[Jason Szumlanski]

Unglazed solar pool heaters are typically sized based on surface area, not
gallons, because most of the heat loss occurs at the surface. They are
rated in daily BTU output, but the test condition rating can be deceiving.
You are really trying to overcome the loss of heat in the long-term, not
heat a particular volume of water. The amount of heating you need varies
with the weather, which causes the heat loss. 70k gallons is a very big
pool. Sounds like your pool is probably about 2000 sq ft. In sunny SW
Florida we shoot for 100% of the surface area. I'm not sure if we are
talking about an unglazed collector, but 25% coverage isn't going to put an
appreciable dent in the heating needs.

There are other sources of potential heat loss, like trenched feed and
return plumbing, low flow rates, features like waterfalls, spillovers, and
fountains, and others.

You may want to look at the Florida Solar Energy Center (FSEC) resources
for solar pool heating:
http://www.fsec.ucf.edu/en/consumer/solar_hot_water/pools/sizing.htm

Jason Szumlanski

On Sun, Apr 5, 2015 at 8:49 PM, Jay <jay.peltz at gmail.com> wrote:

> Hi Tom
>
> Is your doubling of the HE an rule of thumb or is there a formula?
>
> As to system information.
> 510 sq ft collector
> 100,000 btu HE ( main problem I think)
> 70,000 gal pool
> Uncovered ( other main problem. )
>
> The problem is that it's not getting the pool warm.
>
> Thanks for all the help and advice.
>
> Jay
> Peltz power
>
>
> Sent from my iPhone
>
> > On Apr 5, 2015, at 4:56 PM, Tom Lane <tom at ecs-solar.com> wrote:
> >
> > Most heat exchangers for swimming pools are designed for boilers
> delivering 140F or 190F as a heat source based on the size and/ or the
> number gallons in the pool . The solution for a low temperature source like
> solar in order to keep the approach temperature low to the flat plate
> collectors ( and efficiency high ) is to use either double the number of
> heat exchangers recommend for the boiler or using a much larger heat
> exchanger ( twice the size required by a boiler for the recommend pool
> size  )  . Make sure you use a titanium or stainless steel one designed for
> pool chemicals including salt water . DO NOT USE EVACUATED TUBES TO HEAT A
> SWIMMING POOL , ! Use selective coated flat plate collectors if the ambient
> air temperature is -20F to 60 F  when you are heating an indoor swimming
> pool to less than 95F .  Quality Pool Manufacturing , Aico , Triangle Tube
> , and Spirec are among many who make heat exchangers for swimming pools
> suitable for the high flow rates required by s
>  ol
> > ar systems . GatorTom PS : yes they can be used for heating water for
> alligator farms .
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