No Heat This Morning

mattmich

This morning I woke up to 57 F in the living room per the thermostat readout, and no heat. Not fun when it's 13 degrees outside and windy. Jumpering the call for heat didn't work, but some troubleshooting found the culprit to be the Pressuretroll.

The cut-in had been set to an indicated 0.5 PSI with a differential at 1, and when I backed the cut-in screw up past 1 PSI, the heat came on and has been working fine since.

I'm making this a separate discussion so it can have a meaningful title and maybe help someone in the future. The boiler has been working fine since September when I installed it, so why the Pressuretroll decided to wander out of calibration now is a mystery.

To be fair, I'd set the cut-in orginally by running the boiler, turning the screw until the gas turned off, then backing off a full turn(*). That seemed like a good idea at the time, but I won't do that again. Clearly the calibration is not good, since the highest pressure I've ever seen, even today on a long run, is still less than 20 inches of water column, or half a PSI.

So that's my story. No blood no foul, but an uncomfortable half hour this morning before sunrise. Should I worry about my Pressuretroll and replace it? For short-term fixes, I kept the ones from my 1992 Weil-McLain, but I'm not opposed to buying a new unit if it makes sense.

Your comments and suggestions will be appreciatedd.

cheers -m

(*) Bolt-tightening sequence for Harley-Davidson:
"With crescent wrench, tighten until stripped, back off one quarter turn."

Long Beach Ed

If it's a newer snap-switch Honeywell pressuretrol, your problem is not uncommon. You can fiddle with it, increase the pressure to what ever setting is reliable until it isn't or look for a mercury-bulb one on eBay or off a junked boiler.

This Mexican quality is Third-world stuff.

Jamie Hall

If it's been working and now needs a higher pressure setting to work… check the pigtail. It may be getting clogged.

That said, as @Long Beach Ed said the calibration on the microswitch pressure controls is none too good. Best bet is to mount a low pressure gauge on the same pigtail and use that to see what the pressuretrol is really doing…

LRCCBJ

 Clearly the calibration is not good, since the highest pressure I've ever seen, even today on a long run, is still less than 20 inches of water column, or half a PSI.

If you don't make 1 psi on an unlimited run of the boiler, you can simply ignore the fact that you HAVE a pressuretrol. The device is superflous. Just dial it up to "2" and call it a day. Not worth your time.

ratio

If you're running in the inches/H₂O range, consider a vaporstat for control.

JUGHNE

If you try to go too low the mechanism inside can come apart, prevent firing.

mattmia2

it will drift some with ambient temp as the parts expand and contract.

If the old control is the mercury switch type yo could put them in series and run off the old control and set the new control to maybe 4 psig as a safety.

109A_5

I'm kind of wondering why it cut out in the first place, since you said you installed the boiler did you size it correctly ? 1.5 PSI is a lot of pressure for a properly sized boiler IMO.

mattmia2

https://forum.heatinghelp.com/discussion/comment/1840965#Comment_1840965

Probably the first thing to do would be to put a ow pressure gauge on it if you don't already have one. see if on a very long run if it ever builds any more than 1 psig or so anyhow and just turn the control up to maybe 2psig as a safety that should never cut out. i'm sure this is somewhere in the 5 pages of the other thread.