Lwco shuts off when boiler overfilled?

CalamityQueen

My dad has a one-pipe steam system. Bless his heart, he thought he was helping but ended up overfilling the boiler such that water came out of the radiator air vents. We let out enough water so the sight glass level is where it should be and amazingly the system (fingers crossed) seems to be working okay. But I'm confused by what happened with the low-water cut-off.

When the boiler was overfilled, the low-water cut-off went dead. The green light that's usually on was off and the red button did nothing. I assumed it was shot from the overfilling and would need to be replaced. But right before the water level became visible in the sight glass, the low-water cut-off reset itself and now the green light is back on.

Is that normal? Is it monitoring the right/low level? Why would it shut down if the level of water is too high or the boiler is full?

Thank you!

ethicalpaul

The high level of water in your system could have opened the pressure control (pressuretrol) switch which, depending on how your stuff is wired, could have cut power to the LWCO

EBEBRATT-Ed

Agree with @ethicalpaul

The LWCO should not go dead on a high water level

Snowmelt

or it has debris on the tip of the prob giving a false reading, drain boiler take the l.w.c.o off and clean it …..

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1869402#Comment_1869402

Totally agree. And it is surprising how "little" overfill will do this. In many installations the pressure switch and the LWCO (and maybe other safeties) will be wired all in series (there are other way to do this, but this is very common indeed). So — I'd say everything worked the way it was supposed to work.

109A_5

If the pressuretrol (assuming your has a pressuretrol and not some other pressure cut off device) was set for 1.5 PSI Cut Out and 1 PSI Differential, once the water level went above 3.5 feet above the pressuretrol (the weight of the water) I would expect the pressuretrol should shut off the burner, it may shut off other equipment too depending on the boiler's wiring. Once the water level drops below 2.3 feet above the pressuretrol, the pressuretrol should reset. Pressuretrols are notoriously inaccurate so these numbers may vary a bit.

CalamityQueen

https://forum.heatinghelp.com/discussion/comment/1869407#Comment_1869407

Thank you, everyone!

There is a pressuretrol and my guess is this is what happened. (We live in an area where steam heat is rare, so a lot about this system is a little screwy.) Do I have to worry about any damage to the pressuretrol?

STEAM DOCTOR

No need to worry about to the pressuretrol. Just to verify, you could unscrew one of the wires from the ptrol and see if the LWCO goes off

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1869456#Comment_1869456

Keeping in mind that on some installations that wiring is line voltage…

STEAM DOCTOR

True. Turn off the power before you do this

CalamityQueen

Will do. Thank you!

BobC

Some boilers (Smith G8) have the Ptrol and LWO on a 120vb loop instead of the 24v transformer loop so killing your power to the boiler is important.

Bob