Boiler too big ? short cycling ... HIGH PRESSURE ... STEAM ...

[Shemaya]

Hi,
we got a Dunkirk boiler, switching from oil to gas ...

Perhaps the problem in our system is that the boiler is too big for the house, which is a fairly small duplex with upstairs and downstairs one bedroom apartments. The installation has had several problems, which we have been gradually unraveling. The heating/plumbing company that installed it has since gone out of business -- no mystery why!

Anyway, the surging changes in water levels are finally not happening anymore, after rearranging the piping and endless skimming to get all the oily gunk out of the system (three years later). Now, with the heating season just started into more serious activity for nights in the low 20s and days in the 30s in Massachusetts, it's obvious that the system is not all better. It has a pressure gauge which used to run at about 3 pounds -- that was while all the surging was still happening. In the last few days it's been running progressively higher -- today up to 10 pounds. But the system has been short cycling, going on and off five times in the process of raising the temperature at the thermostat from a setting of 60 to a setting of 64. The thermostat seems fine -- when the temperature gets to 64, the boiler shuts off and stays off.

But 10 pounds of pressure seems excessive -- the radiators are spitting, and it never used to run that high. And the adjuster on the pressuretrol is set to cut in at 0.5 and to cut out at 2. On the theory that the "pressuretrol" was not working correctly, or was damaged by all that running with oily gunk in the system, we changed that today to a new one. Now it's running at 9 pounds, which still seems excessive, and it's still short cycling.

The tech people at Dunkirk won't talk to regular human beings -- only to "contractors". We have a friend helping who has done a lot of work on boilers and heating systems, though he's not a "professional". But he has a lot of experience with both heating systems and plumbing, and has done a lot of building maintenance and renovation. He's now 81, and grew up helping his dad who was a steam fitter. That's who put in the new pressuretrol. Dunkirk tech people won't talk with him either. One "professional" took a crack at it last spring, which did help with fixing up the piping so proper skimming could be done, but has not solved the short cycling problem. Another "professional" is supposed to come on December 2 -- but the increasing pressure situation is looking like we had better figure this out before that.

I'm wondering if the boiler has been too big for the building all along, but because of all the surging and gunk problems, this wasn't perfectly clear. Is there anything else that could be causing the pressure to run so high, and the short cycling, that we could check?

Thanks for any ideas,
Shemaya

[rbeck]

Do you think it could be a bad gauge or partially block pigtail (the little curly pipe under the pressurtrol).

[Shemaya]

Hi -- the gauge seems like it must be at least in the ballpark, because when it reads really high, the radiators are behaving like they have really high pressure -- steam coming out the vents, spitting at a newly discovered spot that needed tightening on one radiator. The gauge drops to zero a little while after the boiler shuts off.

While changing the pressurtrol, my friend blew out the pigtail to clear it -- a little water came out but otherwise it seemed open.

Thanks for thinking about this!
Shemaya