I just had a new Raypak heater installed and a check valve becuse i have a salt cell.
Now my filter ( 1 year old hayward 72 sq ft ) pressure gauge stays at ten when i turn off the pump.
If i open the relief valve ( top of filter ) it sucks air in and the gauge will go to zero.
Is this correct operation .
As long as i can remember the gauge has always went to zero with pump off.
Is my gauge bad ? Or did the old leaky heater let air out?
Thanks for any advice...