Fired up boiler for the first time, turns off after a few minutes, internal siphon pressure high

JodiMe

Hi. Just fired up the boiler for the first time this season and after about 10-15 mins I noticed nothing was happening in my office. Went down to the basement and the boiler was hot, but not on. No heat had been pushed. Thermostat shows "heating". It was not doing an intermittent water check. I then noticed the internal siphon pressure was almost 14psi. Pressuretrol is still at the level its always been, .5psi. If I remember correctly, the internal siphon is often not a good indicator of anything, but in years past, it has always remained somewhere in the range of 2-5psi.

Thoughts? Help?

Jamie Hall

Is there another pressure gauge on the same pigtail as the pressuretrol? What does it say?

And... is it the pressuretrol that turned the system off, or something else? If so, what?

My first thought is that something -- or somethings -- is clogged. I'd take things apart and unclog everything that can be unclogged. But... wait until the system is cool; if the internal syphon gauge is correct you do not want to open anything up -- could get very exciting.

Then,, having unclogged and cleaned things, I'd be very much inclined to put a 0 to 3 psi gauge on the same pigtail as the pressuretrol, so that you can see what it's seeing and thinks it's doing. And probably while I was at it add a second pressuretrol on a separate pigtail of the manual reset variety, set higher -- say 3 psi -- as a backup safety.

JodiMe

We don't have another gauge on the pigtail. The boiler did end up pushing heat after I wrote the initial post. When I went back down, the internal siphon was a bit lower, though not by much. I turned the heat off, I'm letting it cool, just to see if the gauge goes down or if it's just stuck in a higher position. I will check the pigtail as I suspect that's probably clogged.... Will update later. Thank you!

JodiMe

Clogged pigtail it was. All cleaned out, internal siphon is back to 0, boiler running fine. Thanks for the suggestions and help!

Jamie Hall

No problem -- and thank you for getting back!