short-cycling steam boiler

Glenn Harrison

Assuming that the guage is accurate, if the guage never reads 1 psi, and the pressuretrol is set at 3 psi, It shouldn't be the pressuretrol. Have you by chance replaced or done work on the thermostat recently, or had other work done to the boiler controls? This sounds like the thermostat anticipator is set way too low. What kind of thermostat do you have? Another possibility, do you have electronic ignition? There may be a problem with this also.

Glenn Harrison Residential Service Tech

Althoff Industries Inc. Mechanical and Electrical Contractors

Crystal Lake, Illinois

Larry_6

short-cycling steam boiler

My home boiler (70000 BTU) cycles on and off very quickly -- it'll run for as little as 1 minute then shut off -- then a few minutes later come on again.
Possibly related: the pressure gauge has never read higher than 1 PSI. I removed the pigtail connecting the Pressuretrol to the boiler the other day. It was plugged-up with sediment and I cleaned it out and re-installed it. Still, the pressure gauge never reads higher than 1 PSI. I have the Pressuretrol set at around 3 PSI.
The boiler generates plenty of steam when it runs...though it's not reaching the radiators furthest down the line even though I just installed a main vent at the end of that line.
I think if the boiler ran for a longer continuous cycle steam would get to the furthest radiators.
Any ideas?

thanks -- Larry

ed wallace

short cycling

set the pressuretrol for .5 on the scale and 1 on the differantial wheel inside the control the less steam pressure the better other than that find someone who understands steam

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[Deleted User]

try these two things

since you have a new main vent try first- you cleaned the pigtail, but how about the inlet to the pressuretrol? clean it and blow in it. you should be able to hear it click the switch when you blow into it. and second- skim the boiler to clean up the water. check its ph also.

Unknown

Is the main vent hot before the boiler short cycles?

If it isn't, you aren't venting as fast as you are steaming, and you are shutting off on the back pressure of the air against the vents. More venting would be called for. You can probably hear the system venting, which is a symptom of too little venting capacity, if this is the case.

Noel