I had a new Pentair 300k btu propane heater installed today to replace the 20-year old oil fired unit that was here when we bought the house. I have not been able to heat the pool with it yet as I am waiting on the gas bottle hookup. But the one thing I immediately noticed was that the pressure gauge on my DE filter is now showing 20 psi whereas with the previous heater the normal pressure was around 12-14 PSI. This kinda surprised me and makes me think that the system is now more constricted than it was before, even though the plumbing has been simplified in the process. He did add a new check valve as well. Is this jump in PSI something to be expected? Is 20 PSI good/bad? I have attached before and after pics for reference.