12-15psi would be more "normal", and adequate for 2 stories. For some low-mass boilers it needs to be a bit higher to limit micro-boil sizzle & hiss at the heat exchanger, but 20psi is usually more than enough. If it's running high it could be that the expansion tank has failed or needs the air charge to be adjusted. I should be big enough, since the Runtal most likely has a lower water volume than the cast iron it replaced.
Most autofill valves have a screw adjustment for setting the pressure but if it's bleeding bu at all it could charge the system to whatever the water pressure is from the street. (I'm not a big fan of autofill valves- it's some thing of a "solution problem". If there's a leak in the system and the pressure goes too low the boiler gives you plenty of sizzle & bang warning well before there's a hazard.)