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Vaporstat/gauge selection advice

nicholas bonham-carter
nicholas bonham-carter Member Posts: 8,576
edited February 2021 in Strictly Steam
I can’t seem to find my old notes on which replacement Vaporstat (0-4 psi), to order. My present one is behaving in a peculiar manner, and causing a lot of short cycling, even though the low pressure gauge reads only a few ounces. Vaporstat (mercury) is set for 2psi, and diff is 8 ounces.
Also need a new low pressure 0-3 psi gauge, as it is too cold to have the boiler out of action while I try and investigate its strange behavior. Who has the best gauge now, as I can’t find the gaugestore.com website now. One of these devices is having trouble.
Another possibility could be that the gas company has raised the incoming pressure, and that the pressure regulator is not able to cope, causing the burner to be overfired, effectively oversizing the boiler. My plan is to get my boiler man to check the gas inlet pressure, and do a combustion test. If that checks out then I’ll order the replacements.
It has been rare for the pressure to rise over 10 ounces, until now.—NBC


  • ChrisJ
    ChrisJ Member Posts: 15,706
    edited February 2021
    Did you clock the meter?

    As far as best, Dwyer Magnehelic by a lot.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • nicholas bonham-carter
    Not yet, as I wonder if, with overpressure the results will be wrong.
    Even the burners on the kitchen stove seem to have higher flames, but that is not a scientific measurement.—NBC
  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    Your existing vapourstat is a mercury type? If so, they don't break. However, they do get out of level -- and level is critical. If the vapourstat seems to be the cause of the short cycling, make sure the pigtail is clear and then, when you put it back on, make sure that it is really level -- and that the orientation of it and the pigtail is such that as the pigtail curls and uncurls with temperature that the level isn't disturbed.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ethicalpaul
    ethicalpaul Member Posts: 5,704
    You can find a LOT of used (or new-old stock) Magnahelic gauges on ebay for about $30. They come in a wide variety of ranges and always measured in inches of water column.

    So here's one that would show you up to about 1psi: https://www.ebay.com/itm/Dwyer-Magnehelic-4-Differential-Pressure-Gauge-0-30-Inches-Of-Water-Model-2030/274672948142
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    JUGHNE Member Posts: 11,062
    Do you have meter and reg in basement? Is reg vented outside, the vent could be frosted over....or outside vent/meter could have same problem.

    Also MUD could have a sub station regulator that is over compensating for your area.
    They might respond if someone reports pressure that is too high.
    They are probably anticipate reports of low pressure this AM with your -20 overnight.
  • mattmia2
    mattmia2 Member Posts: 9,670
    If you are running longer cycles because of it being unusually cold, especially if it is also windy, that could be causing it to run in a steady state that it normally doesn't, it probably gets shut off by the t-stat before the whole system becomes fully heated so the oversized boiler is less apparent.
  • nicholas bonham-carter
    The pressuretrol is shutting down the boiler on pressure, and is level, and before now, had no problems.
    I think Jugne has the right diagnosis-overpressure from the gas company, or the frozen Regulator vent pipes.
    Gas company say that this is probably due to the added propane in the winter mix of gas.-NBC
  • mattmia2
    mattmia2 Member Posts: 9,670
    Propane will increase the energy content of a given volume of gas.