Re: Pump Efficiency
Richard,
I live near you and I have a larger pool, so I had a worse problem. My pressures were similar....21 psi with solar off and 29 psi with solar on. (Actually your pressure difference seems too large...maybe you should consider using a bypass to decrease head loss in solar?) I just changed pumps this summer because I was running a 2 HP Whisperflo and my rate was up to 35 cents/kwh and I was spending $$$$. I also run long run times in the summer to let the solar work well, so it was even worse.
I went with a variable speed pump and my electric bill definitely dropped significantly. I'll private message you the information on the contractor I worked with but there are definitely caveats. Not cheap, but quick payback. Also, they made significant mistakes that I had to stay on top of. Good thing I know my pool....
I have also heard good things about the new Intelliflow pumps. I wish I looked into them more. You set your required flow rate and the pump motor adjusts to get you there, so you will see a difference with solar on/off.
As far as your original question, I don't know the answer except that motors don't run at full-efficency new and get less efficient with age. You can feel your pump running warm right? That is heat loss. I don't know what the standard efficiencies are.
Salinda
owner of ~35,000 gallon plaster IG pool/spa combo. Ikeric Dyna-Miser VS150 filter pump, 2 hp whisperflo spa jet pump, The Pool Cleaner 2x suction cleaner, Clean & Clear Plus 520 cartridge filter, Zodiac Clearwater LM2-40 SWG, Sta-rite 400k heater, solar heat pads and coils.
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