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furnace runs on

I turned down the pressuertrol on my furnace to 1 & 1.5 lbs and stood back to watch what happens and here`s the problem. I noticed that during a normal heating cycle the only time the  furnace kicked off is when the low water level test light came on. The gauge on the front of the furnace never went above 1 lb. of pressure. So I`m curious if the pressuretrol didn't`t shut off the furnace because it never got up to 1.5 lbs of pressure?


  • john walsh_2
    john walsh_2 Member Posts: 64
    boiler keeps running

    Your boiler may not build pressure for a number of reasons. for starters, assuming that your boiler is sized correctly for the connected load, on a real cold day, it's going to take time for the system to come up to steam temp and slow the steam condensing process within the radiators so that pressure can start to build. Apart from that,  bad air valves at the radiators and leaking packing nuts around the radiator stems can contribute to the length of time it takes to build  1.5 pounds of pressure, which is really all you should need. Also check the pigtail that goes to the pressuretrol/ gage to make sure that it's not plugged up with junk and giving you a false reading. There is also the slight possibility that your boiler has a hole above the waterline, allowing steam to escape up the chimney keeping it from building pressure, but you should be able to hear this by manually shutting of the boiler and listening for a strong hissing sound. When it cools down, you can also fill the boiler manually up to the header and look for any leaks. One more thing, if your boiler is OK , (no leaks) and the pigtail clean and the vents are not leaving steam escape  and the heat output of the radiators is sufficient and even on the coldest days, then don't worry about the boiler not building pressure. This could happen if the boiler was to small for the connected load, but the connected load may be more than what is necessary to heat the house.   
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