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Trying to Narrow Temperature Difference Between Floors

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MikeC_3
MikeC_3 Member Posts: 28
edited February 11 in Strictly Steam

As I previously posted, the 4 year old, single zone steam heat system in my mother's 3 story circa 1900 house was working without issue. It first began to short cycle and then shortly after only fired at about 6 hour intervals. The thermostat is programmed for 70 degrees during the day and then only a two degree setback to 68 at night. During the short cycling, the second and third floors were 15 degrees hotter than the first. When the furnace began to fire only 4 times a day, obviously the entire house was cold.

The first technician reset and reprogrammed the thermostat (Honeywell RTH7500D) because he incorrectly claimed that it was the issue. The second technician diagnosed it correctly as a clogged pigtail, replaced it and cleared the pressuretrol (notes attached). The house went back to being much warmer on the top two floors than the first.

I realized that the first technician only programmed the schedule, not the installer options. I changed the system type to conventional, the cycle rate to steam and turned off the adaptive recovery (which fires the boiler early to match the programmed temperature at the programmed time). The boiler now only fires once or twice an hour and the first floor holds steady at 70 and the top two are only about 6 degrees hotter.

I believe there would be even a less of a differential, however the boiler is firing when the temperature is set for 70 degrees and the temperature in the room is still 70 degrees. I assume that there is some sort of anticipator causing this to happen - but shouldn't it only trigger the boiler when it drops below the set temperature? I am not looking for perfect balance, but just something a little closer.

The pressuretrol seems to be set correctly as far as I have researched (attached). The analog gauge doesn't move off of the first hash mark before the boiler shuts off.

Thoughts?

Notes.jpg Pressure1.jpg Pressure2.jpg Guage.jpg

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 27,134

    It's not clear whether this is one pipe steam (with vents on the radiators) or two pipe. The approaches to the imbalance are diffferent.

    Assuming this is one pipe steam, a lot of imbalance can be fixed by changing the vents on the radiators — or adjusting them, if they are adjustable. What sort of vents are on the radiators now? The idea is to put slower vents on the radiators in rooms which are getting too warm.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • MikeC_3
    MikeC_3 Member Posts: 28

    It is a one pipe system. I am sure that balancing is the answer which I plan to explore after this heating season. However, up until this past two weeks and the ensuing issues there was a much smaller difference in temperature between floors.

    Something was altered. Since I was never monitoring it as closely, I am not sure if the thermostat always called for heat while the programmed temperature equaled the room temperature. If it does so based on time and/or temperature, it could have been.

  • 4GenPlumber
    4GenPlumber Member Posts: 79

    Start with the main vent, or vents. When the main vents dont open, steam is lazy, it likes to rise first before slugging along the steam main, depending on how its piped.

    MikeC_3
  • yellowdog
    yellowdog Member Posts: 292

    @MikeC_3 It is awfully hard to balance a steam system after the heating season is over. You should start now while you still have some heating season left.

    MikeC_3

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