Steam boiler cycling due to oversize vent damper wear

melo · 1:32AM

Hello,

I have a steam boiler thats probably 10-12 years old, it's a crown boiler. It's oversized for the space as the baseboard radiators were replaced throughout the house with the smaller steam radiators. Anyways, the thing unfortunately cycles too much, sometimes almost every 30-40 seconds once it really kicks on and tries to maintain temp. Thankfully, our temp catches up quick in the house.

Anyway, my question is more to do with the vent damper which is set to automatic operation. Which means its closing when the boiler turns off. Which basically means it's turning everytime the boiler short cycles.

I'm planning to put it to hold open, I think that's how it used to be previously. Any issues with that? I mean I get the gas usage technically, as now you are letting the heat leave the boiler and up the chimney.

I'm worried that the damper may get stuck and cause more problems.

mattmia2 · 1:41AM

You could also change where the damper motor is in the circuit so it opens and stays open whenever there is a heat call but doesn't close when the vaporstat cycles the boiler off on pressure. Make sure you have solved all of your other system problems so that the radiators are hot all the way across when the boiler cycles off on pressure so the system is at least consuming as much steam as it can. You can also add a time delay so it stays off a little longer before cycling back on.