solar heater

[pkzmf]

we are looking into buying a solar heater but wonder if it hurts the pump because it makes pump work more ???? our pool is 27' round and we bought 2 --2x2x20 how bad will it hurt pump ???? and is this enuff solar heaters

[JohnT]

It won't hurt the pump unless it is oversized and trying to push too much water already. If the pump pressure goes too high, just set the valve to send more through the bypass instead of the panel. You will see heat from 2 panels. More is always better, but you can easily add more later if you have the space.

[ScottEvil]

I made my own solar heater and use a booster pump set on a timer for optimal heating. You should see a 10-15 degree difference between pool temp and heater return line.

[Poconos]

The 10-15 deg rise is too much and the efficiency could be better. Maximum solar efficiency occurs with the lowest temperature differential between inlet and outlet. There is a happy tradeoff between temperature rise and flow. Every system is different and anything is better than nothing especially when it's free. I get about a 4 degree rise on a 4x20' mat heater at around a 15 GPM flow rate (very rough numbers from memory). I don't try and control the flow exactly but shoot for about 1/3 to the field heater, 1/3 to the mat, 1/3 to the returns.
Al

[CarlD]

Al is right.

But there is a paradox. The more water you can flow through the panels, the less of a temperature differential you'll see. This leads people to believe that a lower flow is better.

WRONG!!!!!!!!

The ONLY reason to limit flow is that some part of the plumbing (the pump, the valves, the hoses or the panel itself) is likely to fail from too high or too low pressure. The more water you can flow, the more efficient your system will be and the more heat you'll transfer. Your panels, at peak efficiency, on a blistering hot sunny day, will be no warmer than your pool. While you never achieve this, it is quite common for panels to be cool to the touch when you expect them to burn you.

That's because to warm your pool you are working on transferring HEAT, not temperature. BTUs are what count, gang, not degrees.

[rmeden]

As I mentioned before, I try to keep my rise close to (but not over 10). The reason? I like feeling warm water dropping into the pool! (I have a vacuum hose leaving the panels on the deck and dropping into the pool.. I pull it out when I want to feel. )

I agree I lose some efficiency, but nothing beats feeling the warm water going into the pool. I bet the efficency loss is negligable.

Robert

[JohnT]

I agree I lose some efficiency, but nothing beats feeling the warm water going into the pool. I bet the efficency loss is negligable.

Robert

I would guess the efficiency loss to be in excess of 50%

[tphaggerty]

CarlD is right on for this one. The most efficient panel setup may see less than a 2 degree rise from the panels, but if you're turning over 40gpm vs 10 degrees at 5gpm, that's almost twice as much HEAT going into the pool. Thats why many permanent installations push for as many panels as possible, not only do you get a larger surface area, but you can put through a lot more water. I just saw JohnT's post, I would have to agree that it is probably that or more.

But, if your pool is at or close to where you want it to be, I like the idea of slowing it down and getting a warm rush from the returns!

[CarlD]

But, if your pool is at or close to where you want it to be, I like the idea of slowing it down and getting a warm rush from the returns!

There's ANOTHER way to get that

[rmeden]

I would guess the efficiency loss to be in excess of 50%

*WOW* that much? I was thinking less than 10%... we're talking about a 77->87 degree rise... you're saying a 77->80 degree would put twice as many BTUs in the water?

Granted, I never had thermo in college, but that seems a bit much...

Robert