Good afternoon. I have noticed lately that my house pressure creaps up to approx 110 psi (per a lazy arm gauge on a faucet). The Pressure Regulator (PR) located where the water pipe enters the house is set for approx 55 psi as is the thermal expansion tank. I recently flushed out the PR out by removing the 2 plugs, screen, etc and running some flow through it. With the water feed turned off (no pressure) checked the expansion tank, found no water inside it and re-set it to 55. When I turn on a faucet in the house I get a burst of high pressure then it tapers off to approx 55. The gauge I have on a faucet generally reads 60 but the lazy arm almost always indicates the pressure has crept up to 110 (+/-). I checked the pressure relief valve (PRV) on the heater and turned it on/off a few time to make sure it is operating and get flow when open, no flow when closed. The heater is a 50 gal gas fired one, the expansion tank is a Wilkins WXTP-8A. I give up, any thoughts as to what may be the problem will be most appreciated.