Vacumn @ boiler 2-pipe System?

Dan Wood_2

We are working on an old P.M. Lattner fire tube boiler with Hoffman return trap. My tech went to drain off some water at the bottom of the boiler. When he did he found the system in a vacumn and the drain sucked in air. The unit was cycled off at the time. It is about a 5000 sq ft house with a few end main bucket traps. And of course it is a two pipe system.

Can a end of main vent let air in but not out?

Unknown

Yes,

A lot of the old coal vapor/vacuum systems had vacuum vents on them.

Not needed where the steam cycles on and off. A regular "2-way" vent, like Gorton #2, would solve that.

Noel

Dan Wood_2

reply

Noel, Thanks for the reply. I guess I knew that, but didn't give it
consideration because the system has standard pressuretrol although the gauge is
a vacumn/pres. style. After I posted the question I talked w/ my tech. He was changing a
bucket trap and noticed the return was flooded. He found what he thinks
was a gate valve broke in a mostly closed position. I am not sure of
the location of the valve and if that would have effected a vacumn in
the boiler. This vacumn was severe enough that it effected the static
water line. The home has new owners and no auto feed valve. So I not
clear on it's history of operation. I am going to have them give me
more specific input on much feed water they are putting in it.

Thanks Dan

Unknown

Sure it could affect it

If the vent, or vented tank, was beyond the broken valve (opposite side from the steam supply piping), it could prevent air from coming back to the boiler to break the vacuum.

Noel