I used a Taco Cartridge Pressure Reducing Valve for my new Boiler. Is there a difference from that valve to a boiler fill valve? I seem to think they work slightly different and I may have used the wrong valve to for the fresh water. Plus my pressure in the system started at 12 and gained 2 psi every day without even firing the boiler up. The system is fully bled of air and I ran it for a while and the pressure went to 21psi so I shut it all down and let it sit for days and released the pressure to 12 and left it off and thats when it started to creep up each day. It's been 3 days and it went from 12 psi to 16 psi without running.
I got a new expansion tank charged and checked to 12psi before installation...
I'm thinking the PRV is not the right type and will replace it but that;s why I'm asking if there is a difference between the two types.