Frequent Boiler Interruption

Abinoone · March 4

My 28-unit cooperative apartment association, located in upstate NY, had a new boiler installed two years ago to replace an old unit. Since then, the boiler often will simply stop working - at times a daily occurrence, requiring the system to be reset manually to get it running again. We've spoken to the contractor who installed it, and the explanation he gives is that the older steam traps aren't working properly, affecting the flow of water back to the boiler, which "tricks" the boiler into thinking there's not enough water, causing a shutdown. His solution is to replace all traps in the building at a considerable cost. Since we never had this problem with the old boiler (with the same traps) we're uncertain if what were being told is true, but then we're all novices. Any advice you may be able to provide would be greatly appreciated.

Thank you.

Jamie Hall · March 4

Well… the first thing to do is to figure out what is shutting the boiler down. It might be low water. It might be high pressure. It might be a wonky connection somewhere. It might be a combustion or fuel delivery problem to the burner. Until you figure out what the actual problem is, you don't have much hope of fixing it.

It's unlikely to be a rash of bad traps. First off, they usually fail open — they'd have to fail closed to trap condensate. So honestly that's about the last place I'd look for a problem.

So figure out what is shutting off the boiler…

Like, for starters, what are you doing to "reset" the boiler manually? Which button do you push?

EBEBRATT-Ed · March 4

Yeah, you have to find out which control or controls are shutting the boiler down. Its possible but not likely that a bunch of bad traps failing closed would starve the boiler of water but I doubt it.

What are you resetting to get the boiler started?

It is possible your traps if they have never been serviced need replacement.

For a trap guy who knows how to do this its not a huge issue. You can buy the parts to rebuild almost any trap and the rebuild consists of taking the top off the trap and pulling out the internals and replacing them and reinstalling the cap. Maybe 20 min /trap on average wehn someone is all set up to go.

Of course if you have to move stuff or the traps are difficult to access that is an issue.

LRCCBJ · March 4

the explanation he gives is that the older steam traps aren't working properly, affecting the flow of water back to the boiler, which "tricks" the boiler into thinking there's not enough water, causing a shutdown

Here is how you can easily prove him wrong.

When the boiler shuts down, go to the boiler and take a photo of the sight glass (the 12" glass tube on the side of the boiler). If you can see water about 2" (or more) from the bottom of the glass, you have proved that he lied to you.

I agree with Jamie and ED…………….determine why it shuts down.

pecmsg · March 4

pictures of the control settings will also help

EdTheHeaterMan · March 4

Most commercial boilers are equipped with two limit controls. One is the operating control. The operating control will automatically reset. The other is the redundant control and should be a manual reset to stop the burner in the event the operating controls fails in the closed (turned on) position. If you are needing to reset the secondary limit control often, then the operating control is not working properly, or the two controls are set too close to each other. Find out what control you are resetting. Is it pressure or is it low water cut off, or is it a combustion gas vent spill switch or is it a high temperature switch.

Once you know what you are resetting, then we can go from there.

Based on the plumbers response to your query, I bet it is the Low Water Cut Off limit control LWCO. If you have two of them, then the higher LWCO should stop the burner long before the water drops below the level of the back-up LWCO. someone needs to rethink that design.

mattmia2 · March 4

If it is 2 pipe some pressure differential could be causing the water to be pushed out of the boiler at some point although it is much more likely to leave as a liquid because of surging or priming.

Long Beach Ed · March 4

As mattmia2 suggests, make sure the boiler water is clean and all oil is skimmed from it.

Frequent Boiler Interruption

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