My boiler is running at 20psi cold. I'm concerned this is too high. I'm using a bladder type expansion tank and Taco autofill valve (boiler feed). The convectors are cast iron radiations. The house is a 2 story cape with the boiler located in the basement. The fill valve is before the expansion tank which is in the return side of the boiler. The pumps are located on the supply side, so pumping away.

I've been reading up on this subject and have some items to check. The air pressure in the expansion tank is the factory fill so will be checking that this weekend. The fill valve is brand new, replaced over the summer, and it too has the factory setting.

My only concern is I installed the fill valve vertically, due to space restrictions in the system. I just noticed the Taco documentation says to install horizontally. Do you think this would cause a high pressure problem? Should I relocate the fill valve to a horizontal position?