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Psi reaching 5?

cynthia07104
cynthia07104 Member Posts: 48
edited January 2019 in THE MAIN WALL
I have a 1 pipe system and am noticing the pressure is building up to 5psi before the boiler cutting off. What could be causing this?? The tenants have their thermostat set at 75 degrees and their boiler is constantly running. As soon as the psi drops down the boiler is cycling on again and continues until it reaches a Psi of 5. What should I be looking at when troubleshooting?? Also how dangerous is it reaching such a high PSI it was my understanding it shouldn’t be higher than a 2.

Comments

  • JUGHNE
    JUGHNE Member Posts: 11,312
    Pigtail plugged?
    Set control as low as it will go without falling apart.

    What does the gauge read when boiler is off for 10 minutes?
  • cynthia07104
    cynthia07104 Member Posts: 48
    Here’s a full picture of the boiler.
  • Fred
    Fred Member Posts: 8,542
    @cynthia07104 , the Pressuretrol is mounted right on the McDonnell Miller #67 Low Water Cut -Off. Probably the worst place for it as that tapping in the LWCO and the pigtail will clog at least twice each heating season. The pigtail need to be taken off and cleaned as well as the tapping in the top of the LWCO. Actually, the LWCO should also be tested to make sure it works. They are suppose to be taken apart and scraped out once a year and McDonnell Miller recommends the entire unit be replaced every ten years. That one looks like it hasn't been touched in years.
  • cynthia07104
    cynthia07104 Member Posts: 48
    Going to shut it down and clean the pigtail and the LWCO. Had no idea it had to be replaced every 10 years. I’m not sure how old it is but I know I have never cleaned it. I didn’t even know it was something that had to be done.
  • Fred
    Fred Member Posts: 8,542
    cynthia07104 said:

    Going to shut it down and clean the pigtail and the LWCO. Had no idea it had to be replaced every 10 years. I’m not sure how old it is but I know I have never cleaned it. I didn’t even know it was something that had to be done.

    There is a gasket set that you need to buy, before you take it apart. You can order them from Supplyhouse.com I would clean the pigtail and the straight pipe on the top of the MM#67 and make sure the LWCO still works while waiting on the gaskets.
    cynthia07104Ironman
  • cynthia07104
    cynthia07104 Member Posts: 48
    @fred you mentioned the pigtail is probably in one of the worst locations. Would I just remove it from its location and plug the hole in the LWCO?
  • Fred
    Fred Member Posts: 8,542
    cynthia07104 said:

    @fred you mentioned the pigtail is probably in one of the worst locations. Would I just remove it from its location and plug the hole in the LWCO?

    Yes, if you have somewhere else on the boiler, above the water line that you can move it to. The plug that goes into the top of the LWCO is just a 1/4" plug.
  • cynthia07104
    cynthia07104 Member Posts: 48
    Great thanks going to try to get that done tomorrow.

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