I have a water heater that has both a pressure relief valve and a back flow prevention valve (BFP). It seems that the BFP (which is an 80psi) is continuously running. I checked the pressure in the hot water heater and it is 90psi (all the time) which makes sense why the 80psi valve is always open. I checked the hose bibs pressure and initially it was 90psi also. I lowered the whole house pressure and got the hose bibs down to 75psi. No matter what I do the house pressure, the water heater is above 80psi. I open the pressure relief valve on the water heater with the guage attached and saw the pressure go down to 60psi but within 2 minutes it was back to 90psi. How do I get the pressure in the heater down? I would understand if the BFP was leaking hot water (which expanded) but it's leaking cold water from the input line most of the time. Any advice on what to check, set, or install would be much appreciated...I'm watching hundreds of dollars a year leak down my drain tube at this point.