I have a Weil-McLean CGa gold boiler. Up untill this year I haven’t been been having a problem! When the unit calls for heat the pressure gauge drops 2-3psi. It was at 12 psi cold but when heat called I’d be in the 8-9psi. Once the water heated up the pressure did rise like it should. I upped the cold psi to around 15psi so when the pump kicks on it doesn’t go lower then 12psi. The unit is piped this so, boiler unit pipe goes up gauge then pump. Does anyone know why this is happening all of the sudden?