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I have 35 year old boiler with a honeywell pressuretrol. The heat had been running when needed for about a week with no signs of trouble. However, the other night it was damp and rainy and the boiler would not go on the next morning. There was sufficient water in the boiler and new batteries in the thermostat. Wiring had been replaced last year. I figured I would check contact points. I started with the pressuretrol. As soon as I took the cover off of it, the boiler started. I have a Utica millivolt boiler from the mid- seventies. The pressuretrol's serial number begins with PA404A. Can anyone tell me what happened?


  • BobC
    BobC Member Posts: 5,479
    Ozidized switch contacts?

    If this pressuretrol has a brown switch inside the switch contacts may have oxidized; when you disturbed it the contact was made. The pressure diaphram could be suspect but they usually just fail. Make sure the wires are screwed down tightly. If it happens again you might have to replace the pressuretrol.

    The thermocouple cold be going but the fact it started when you fiddled with the pressuretrol points to it.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
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