I just installed a new water pressure regulator as documented in Water Pressure Regulator not regulating after rebuild.
I left the pressure gauge attached to a hose bib with the faucet turned on so I could monitor the pressure over the course of a cpl days. My gauge has a red, maximum pressure, hand to record the highest measured pressure during that measurement period.
So far everything is working as expected, and it's able to control the pressure to 60psi where I set it, except sometimes when I leave and come back several hours later, I see the maximum pressure hand read high over the 60psi.
Once it was up at 80psi, the other time it was at 110psi (from other tests I've done, I assume 110psi is the city water pressure level, and this is the same pressure I was reading on the old regulator that went bad before I replaced it).
From reading other articles on the site, I understand one possible cause is the water heater heat cycle expanding the water and increasing the pressure in the system, although I'm not sure about this.
I don't see an expansion tank on my water heater, and I don't think there's any pressure release valve anywhere in my house water line.
Any ideas what the issue could be, and how I can solve it?