Last winter my gas-fired boiler refused to fire, even after replacing the
low-water cutoff switch, the pilot generator, and eventually the gas valve.
After poking and prodding everything that seemed to move, I lifted the indicator
on the steam pressure cutoff box and the burners finally lit off. When I took
my fingers off the indicator, the burners went out. "Hmmm", thought I. "Another
adjustment that probably went awry."
I turned the screw at the top of the switch box until the burners lit and stayed
lit and congratulated myself on my brilliant deduction.
I awoke the next morning to a great whooshing noise emanating from the basement,
and discovered the room full of steam. The relief valve on the boiler was open
and gushing steam "everwhar". Ot was so damp down there, the flourescent lights
wouldn't go on. After filling the boiler with cold water to bring the pressure
down, and exhaustiing the steam outdoors with a fan, I turned the cutoff switch
screw back to where I thought it was originally. Of course, the boiler wouldn't
fire again, and I finally discovered that that curly pipe going to the bottom of
the switch box was plugged with rust. I replaced the pipe, and the furnace has
been working dependably since then.
However, one thing concerns me:
The pressure gauge on the boiler reads around 4-7 lbs when it's really
humming since we've had this cold spell, and I think the cutoff switch isn't
adjusted correctly. The boiler never exceeded 2 lbs. back in the days before
things started wearing out on the unit.
Can anyone enlighten me as to the proper adjustment procedure for the steam
pressure cutoff?