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Never build pressure

Steam isn't my strong suit, so I'm going to pass on this one. If no one else responds, you might post your questions on the main part of "The Wall" on this website.


  • Foreman
    Foreman Member Posts: 30
    Never build pressure

    On normal heating cycles I never build steam pressure for pressure-trol to shut burner down, unless I raise temperature on Stat aprox 4 degrees. (in other words, keeping the burner on longer) Pressure and differential are to set to lowest setting. Is it normal NOT to build any measurable pressure with a normal cycle, unless burner stays on longer? Mains are insulated and no leaks or faulty vents, boiler sized properly also. Would a vaporstat shut down burner, while still producing steam and rad vents still open? What Im aiming for is maintaining steam, while burner cycles on pressure.

  • ttekushan_3
    ttekushan_3 Member Posts: 940

    Its not unusual to have systems that don't appear to build pressure. Actually, its more efficient with a perfectly matched boiler so that it operates the way you describe.

    IF the system heats evenly and otherwise shows no signs of malfunction, its probable that the system was originally designed to operate effectively with ounces of pressure. Its really quite efficient that way.

    So what you may need is a "Vaporstat" which regulates pressure in ounces, rather than a standard pressuretrol which regulates in pounds.

    You may also consider a pressure guage that resolves in ounces. If steam is flowing, there definitely is measureable pressure. Your guage is just not showing it.

    I've seen systems that never, ever build more than a pound of pressure. This is not inherently abnormal for a well designed low pressure steam system.

    Note: you don't want the boiler to cycle off until the radiators are reaching saturation and all the air is expelled from the system. What happens is that if the boiler cycles off too early, the air in the system expands also, and the consensing steam pulls cool room air into the radiators. This exaggerates system heat imbalances.

  • Rich W
    Rich W Member Posts: 175

    If the burner stays on longer when you raise the temperature 4deg. it's not a pressuretrol problem. The heat anticipator needs to be adjusted to a higher setting on your thermostat(or fewer cycles/hour on a digital). If the reading at the 'stat is .5amps, I would start with a setting of .6 on the anticipator- maybe even .7amps. This will give you a longer run time before the 'stat turns off the burner circuit.

    good luck
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