Suburban SW6DE Water Heater - Water Too Hot Gas AND Electric...

[MR.M]

Originally Posted by BehindBars

I think you’re right about city pressure above 62 PSI possibly filling the fresh water tank. That is something to think about. I use a 40-45 PSI regulator on the city water line, and I guess that’s a good reason to do it.

The by pass doesn't work that way . the pump has a built in check valve to stop water from back filling tanks . many have added an additional check valve when the pump valve fails . the by-pass is built in for when you may have a faucet open partially so the pump doesn't cycle as much . it just allows the water to move around in the pump . as nothing to do with back flow

[nomad297]

What SHURFLO writes about the bypass:

“NOTE: By-pass adjustment should only be performed by a professional techni- cian with proper gauges and equipment.
The by-pass is a spring loaded dia- phragm 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 (lower pressure pumps will vary depending on the by-pass and pressure shut-off settings). The pres- sure switch on the pump is set to shut off at 55 psi. 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. Unscrew- ing the switch screw counterclockwise 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 coun- terclockwise 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-pass pressure setting should be at least 10 psi higher than pump shut off pressure.”

The bypass will not help solve the problems associated with thermal expansion.

Bruce