I read the part on operation and adjustment but didn't quite get it. First it states it should not cycle even at a trickle. Mine does not do this.
Originally Posted by Happy Vibe
I looked at the instruction manual at shurflo and it sounds like your pump is not setup properly. The pump should continue to run if a tap is open. You may want to adjust the pressure setting as discribed in the manual.
This pump is designed for intermittent duty only. The pump operates normally up to about 40-psi, where a spring-loaded by-pass valve opens, allowing flow back from the output side to the input side, providing smooth, steady flow with virtually no cycling, all the way down to a trickle.
As a faucet is opened back up, the pressure will drop, the by-pass will close and full flow is again obtained. This allows good flow, even with today’s restrictive showers and pullout sprayer faucets. Performance will vary, of course, depending on the voltage to the pump; lower voltage = lower flow, higher voltage = higher flow. Remember your electrical safety: It is always best to shut power to the pump OFF when leaving the RV unattended.
About The By-Pass NOTE: By-pass adjustment should be performed by professional technicians with proper gauges and equipment.
Now for the adjustment. I assume I leave the "switch" screw alone and adjust the "by-pass" screw. Which way?
The by-pass is a spring loaded diaphragm that opens up allowing water from the discharge side back to the inlet side. The by-pass is set to begin opening at about 40 psi and creating full by-pass at about 62 psi (for 55 psi models), lower pressure pumps will vary depending on the by-pass and pressure switch settings. If the switch or by -pass are adjusted too much, the by-pass and switch shut-off can overlap and THE PUMP WILL NOT SHUT OFF. Screwing the switch screw in clockwise will raise the shut-off pressure. Unscrewing the switch screw counter clockwise will lower the pump shut-off pressure. Screwing the by-pass screw in will raise the pressure at which the by-pass starts and raise the full by-pass pressure. Unscrewing the by-pass screw counter clockwise will lower the pressure at which by-pass starts and lower the full by-pass pressure.
WARNING: If full by-pass is reached before the shut-off setting, the pump will not shut off. Full by-passpressure setting should be at least 5 psi higher than pump shut off pressure.