n240sxguy,
Both pumps 1 HP, the old had a SF of 1.4, the new a SF 1.25. I should add the old pump was over a decade old and was coaxed through last summer only with plastic welding and bondo.
The same gauge was NOT used on both pumps. Last year's gauge was dead by this spring so I replaced it.
mas985,
Yes, I always switch off the pump before changing from one mode to another.
I updated my signature already. The old pump was a very old A.O. Smith Century Centurian B128; the new is a Pentair Superflo Dual Speed.
Let me add some further data in case it may be relevant.
Starting last summer I began seeing air bubbles coming from the returns upon starting the pump, so I figured I had a suction side leak somewhere to diagnose this spring.
The old pump was DOA this spring and would not start, which set back my opening by a week and had me worried about a big algae issue, as I typically have leaf reside/sludge on the bottom from holes in the mesh cover. After installing the new pump and starting it I was not surprised to see I still had some air bubbles coming from the returns, but not only on start up, but fairly continuously. Still, given the late opening and the fact the pump seemed to be working great beyond the air bubbles and the mentioned higher pressure reading, I have been running it while watching it closely and backwashing frequently as soon as pressure rises to about 22 psi.
Obviously I have to diagnose and address the suction leak issue, but I was focusing first on getting the pool open and hopefully passing the 3 SLAM tests. The water is improving over the past 2 days but is still very cloudy so I continue to SLAM and backwash. It's progressed from swamp like to light green and cloudy and seemingly improving each day.
I have never swaped out pumps before though, so wasn't sure if this increase in typically pressure was an indication of further concern - perhaps my sand filter needing a deep cleaning - or if it was a non issue. That's why I only asked about the pressure issue, since I am trying to prioritize my troubleshooting between pumps, leaks and filters! Given the answers so far, I figured the additional information might be relevant, so I offer it now.
I'm also surprised to see that when I run the pump on the slow speed the pressure drops way down to about 5 psi, and although it manages to maintain prime the water level in the basket drops visibly to about half full. Does this sound normal? I've never had a dual speed pump before.
So to recap, my concerns/questions are:
1. Should I be concerned that the new pump operates at about 20 psi vs the old pump of 15 psi?
2. Is it typical for the low speed on a dual speed pump to have a pressure of about 25% of the fast speed? (5 psi vs 20 psi?)
3. Could the new pressure gauge be the source of this pressure change?
4. Could my suction side leaks be contributing to this pressure issue, or would that be limited to air bubbles in the return?
5. Could the pressure issue be caused by an algae bloom or problem in my sand filter that should be deep cleaned to improve the pressure?
Sorry for the long treatise, and any feedback or suggestions welcomed.
