Reducing Pump Pressure To Make Solar More Efficient

[CaptainBusy]

I have a 15x30 aboveground pool that makes use of a solar heater. My first pool filter/pump was 1 HP and that proved to be too much for both a small pool and two banks of 4x20 solar collectors plumbed into the system. I replaced the pump with a 3/4 HP Hayward pump and both elevated and added an additional solar panel. Still... the output from even a 3/4 HP pump is more than the solar needs to have water pumped through the system.

Is there a way to reduce pressure from creating more back or head pressure in the system verses stressing the system by gating down flow, or is this acceptable, using ball valves in the system to reduce the diameter of the discharge piping in the valve?

Thank you in advance for you response and assistance,

Mike Schlags

[email protected]

Santa Barbara, CA

[Dr. Spa]

I'm not quite sure why you're trying to reduce the flow through the panels. Valving the pump will cause it to work harder and use more power to operate.

From the title of your post, it sounds like you might think that slowing the water flow through the panels will increase their efficiency? This is typically not the case...in fact, you may very well actually decrease their efficiency by lowering the flow rate.

So why? Well lets say at your current flow rate the water going through the panels is gaining 5 degrees, and by reducing the flow you could gain 15 degrees. Logic would say that to do this you'd have to reduce the flow by two thirds. So, one third the flow rate, three times the temp gain, it's a complete wash. Or is it? No, actually, it's not a wash. It take MORE than three times the solar power to increase the temp rise three-fold. Also, as the temp increases, you have MORE heat loss from the water to the atmosphere (Newtons law of cooling).

If you're thinking that the water is traveling too fast through the panels to absorb the heat the panels have "captured", this too is incorrect. The panels absorb and transfer to the water ENERGY. Transference of energy is completely different than that of "solid" material.

BUT. If your solar panels are made of a metal (copper), there should be a rated flow rate. If you exceed this, the water flow will actually wear away the metal.

[Dr. Spa]

Here another explanation...The sun isn't actually heating the water. The sun heats the solar panels, then the water flowing through absorbs the heat from the panels and carries it back to the pool.

[Flapjack0023]

The rate of transfer of heat is dependent on the temperature difference. As the temperature difference gets smaller, heat exchange slows. Faster flow through the panels may only raise the discharge temp by a few degrees, but in the end, puts more heat into the pool.

[Wizzard of spas]

I have a 15x30 aboveground pool that makes use of a solar heater. My first pool filter/pump was 1 HP and that proved to be too much for both a small pool and two banks of 4x20 solar collectors plumbed into the system. I replaced the pump with a 3/4 HP Hayward pump and both elevated and added an additional solar panel. Still... the output from even a 3/4 HP pump is more than the solar needs to have water pumped through the system.

Is there a way to reduce pressure from creating more back or head pressure in the system verses stressing the system by gating down flow, or is this acceptable, using ball valves in the system to reduce the diameter of the discharge piping in the valve?

Thank you in advance for you response and assistance,

Mike Schlags

[email protected]

Santa Barbara, CA

[/quote

Yes of course there is a solution. This solor system should have a bypass valve, you adjust the valve to create the desired amount of flow to the solar sys. The rest of the water is returned dorectly to the pool. Better keep the 1 horse pump, you still need filtration. Keep knocking that pump HP down, and you will be running a swimming pool on a fish tank pump.