Hi new to this forum so hopefully explaining this correctly. Before I added my pool heaters my filter pressure was at 10 after backwash and new DE. I then added a Hayward heat pump and a Raypak propane heater. The Raypak has a built in bypass however the Hayward does not. It appears that the Hayward heat pump is causing the pressure to go from my old normal 10 to with heat pump valves on 20. Is this normal?