Steam boiler keeps shutting off

Unknown

do you have on the boiler? Is it gas or oil? If it is gas it may be a self generating system, if it is they do just what you say yours is doing. Let me know!!! Then I can perhps help you.

Joe_23

steam boiler keeps shutting off

I have a one pipe steam boiler system in my house. The boiler will fire up and create steam which is sent to all of the radiators in the house, but it shuts off and dosen't come back on for a while, sometimes a few hours. I checked the water level and it seems fine. The thermostat is set at 70 degrees, although the temperature in the house hasn't reached above 62 degrees. Even if I set the thermostat to 80 degrees, the boiler dosen't fire back up. The radiators will become cold before the boiler starts up again. I replaced the thermostat, thinking it may have not have been functioning properly, but this did not help. Any ideas about why the boiler keeps shutting off without reaching the set temperature or why it takes so long to come back on?

tim smith_2

boiler shutting off

I am wondering if you are shutting down on low water cutoff, this sounds like a possibility, if your feed line was blocked or even shut off it might seep just a little water to boiler to get water level up just high enough to restart but then as soon as a little steam off occurs the water level would drop and shut down boiler. 1st initial thought???

techheat_2

Check the pigtail

David Efflandt

Could be the unexpected

For problems like this, it helps to know how to use a volt-ohm meter and trace circuits, so you could figure out what is interrupting its operation. Could have at least saved you the price of a thermostat.

My problem was hidden by previous owner setting pressuretrol way up. Once I set it as low as it goes, it would run for awhile, kick off before it reached temperature, and sometimes not come back on for hours. But it was mild weather and problem intermittant, so I had to catch it in the act. Because it did it when hot, I thought it might be a rollout switch.

Finally figured out that that the vent damper would not open automatically when hot, even though it had power to all the right contacts. So once the boiler ran for awhile and started pressure cycling, the damper would close and not automatically reopen (even though power to all the right contacts). But when opened with its electric manual override switch (which did work even when hot), the boiler fired right up and worked fine. New vent damper solved it.

That is not to say that this might be your problem, but with all the safeguards and controls, if you start replacing things without determining the cause, it will likely be the last thing you could possibly guess.

Joe_23

Yes, the boiler is on and it is gas. The heat was working fine for about two weeks, then it started acting like described. The other thing I have noticed is that the thermostat used to click and turn on the boiler, when the temperature setting was raised above the room temperature. This does not happen anymore no matter what temperature I set the thermostat to. The room temperature on the thermostat seems to stay right around 62 degrees. The boiler seems to come on if that temperature drops.

Unknown

Is it a 24 volt system or

a millivolt system? It sounds like you may have a millivolt system. If that is the case you will have to take some multi-meter readings to determine if you have sufficient millivolts to power the system. This erratic behavior is typical when resisitance of controls combined with a low generator output are involved. Is the thermostat a round one if so pull the cover off and see if you can find some numbers on the original thermostat you replaced.

Joe_23

It is a millivolt system

The original thermostat was a round Honeywell thermostat. I replaced it with another round Honeywell (heat only) thermostat. What kind of information would I be looking for on the old thermostat?

Jay_6

Yes, checking the pigtail is a good idea.If that is partially blocked, running the system for a bit will open the pressure-trol.Make sure its clean, or replace it.While we are on the subject, what is the position of the pressure-trol.make sure it is well above the water line.The short cycling of a steam boiler can have many causes.One thing you dont mention is if this is a new boiler, or if this has just started happening to a exsisting boiler that was working fine.If it is an exsisting boiler that was working fine, i would approach it this way:
1.-check the pig tail
2.-check your t-stat, heat anticipator settings,calibration ect..(T-87s are cheap enough to replace if its old)
3.Check your water level condition.Is it surging ect..maybe the boiler needs to be skimmed....

Just a few thoughts on the subject....Jay

Unknown

If it is Millivolt

the T87 with the anticipator is the wrong thermostat. That one's for 24 volt systems

Noel

Unknown

If it is a millivolt system

the old thermostat should be a TS86 millivolt thermostat. If you use a T87F it is for 24 volts and if the anticipator is set too low you will have a very high millivolt drop across the thermostat which can hold the boiler off. You need to have a complete set of millivolt readings taken by a professional. Just for some info as to what is normal:

The output of the pilot generator should be around 750 millivolts the minimum is 540.

With the gas valve energized you should have about 350 to 360. Anything above 380 is too high.

Maximum drop across any switches should be 10 millivolts.

Look for any loose or poor connections as these can rob millivolts.

You may also want to check gas pressure to equipment it should be 7 to 10 inches water column. And after the gas valve 3.5" to 4" water column.

As others have suggested clean the pigtail for the pressuretrol. Have you been regularly flushing the LWCO it may be that the float is stuck and needs cleaned.

Self generating systems can be very tricky and really need some one with a lot of experince to properly troubleshoot them.

Frank_15

dont be so cheap

stop being so cheap and call someone to come look at it.

Joe_23

heat is fixed

I want to thank everyone for their advice. It turns out that it was the pigtail. I replaced it and everything is working fine.