Convert solar collector into pool heater?

[goodgnus]

I had a solar water heater from the 80's, recently replaced with an energy efficient all electric.

I have a huge solar collector on my roof. Any ideas on converting it into a pool heater? IE pump water in, monitor temp in collector (I would have to install new thermometer or temp sensitive relay?, pretty sure it's not functional anymore), when hot pump into pool and refill solar collector from pool.

Wondering if anyone has done this?

 

[Belldiver]

I think it's a good idea in theory, but unless you have a very small pool, it's probably not enough to make a dent. The usual rule of thumb seems to be surface area of the solar collectors needs to be 50-100% of your pool surface area. This is also affected greatly by your location...amount of sunlight, air temperatures, use of a solar cover on your pool, etc...

I'm sure a couple others will chime in here soon too...

 

[JasonLion]

The design of domestic hot water solar panels and swimming pool solar panels is normally very different. Domestic hot water is trying for fairly high temperature gain and low flow rates, while swimming pool solar panels are trying for low temperature gain and high flow rates. Still, they will provide heat and every little bit of heat helps.

You will be able to control them with a standard swimming pool solar controller (or manually). The main challenge is figuring out the right flow rate, presumably fairly low compared to a swimming pool solar panel.

 

[Sabot]

My solar guy said those can produce enough heat to soften the PVC over long hours of use. Plus from what I recall, the copper in them might not like the chlorine very well.

 

[JasonLion]

If they have copper pipes, which is common but not universal, the issues are the same as for a copper heat exchange coil in a pool heater. The crucial thing is to keep the PH from getting below 7.0.

Depending on the flow rate you can achieve the water coming out of the panel might be too hot for PVC. If so, you will need to use high temperature pipe till it gets mixed with some pool water.

Using domestic hot water panels to heat a pool is not normally a great idea, but if they are just sitting there unused then I say go for it.

 

[tphaggerty]

I would do it too. Check out CPVC, they carry it at home depot etc. It is used for domestic piping and is rated for high temp (you do need special glue and fittings). Since you are going to have to really limit the flow anyway, you can probably use much smaller pipe than normal solar and you will want to use a bypass so you can adjust the flow rate/pressure.