Finally comfort in small cape cod

Fizz

with single pipe steam. In second season in this house after leaving comfort of Richardson System in vacuum at prior house(switched t-stat from old round h-well merc to round h-well set to hot water setting which provided steady comfort). Orig t-stat was old rectangular honeywell merc, tried two other mechanicals, the Robertshaw(now Invensis) 986-1R and the White-Rodgers 1E30N-910 with similar results, temp swings of 4 degrees, and few minutes of some vents hissing, with boier pressure occasionally reaching 16-20 oz and bringing p-trol into play for shut-down. so I swapped out to W-R(Emerson) 1E78-140 heat only. What a difference; have t-stat set at 71 and never moves! Boiler cycles for7-10 min, and because house is so small, EDR of 218, rads never get cool, steam never gets to air vents(no hissing on very cold temps out-side) and pressure is between 1-4 oz, t-stat always turns off boiler.