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Radiator vents open and close repeatedly

Lately my radiator vents are opening and closing repeatedly, especially during the initial part of a cycle. The open and close times are around a minute or so. The vents hiss fairly loudly when open and make a noticeable sound when they close. The vents were replaced a few months ago. The radiators are single-pipe. Anyone know what could cause this and whether it means something is amiss?

Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    What make of radiator, and main vents are on the system?
    What is the pressure of the system?—NBC
  • dopey27177
    dopey27177 Member Posts: 887
    Your steam pressure may be set to high.

    Your boiler pressure should be no more than 3 PSIG with a 1 pound drop back.

    Jake
  • jimb245
    jimb245 Member Posts: 6
    The embossing on the radiators is American Radiator. The main vents are Dole Valve No 3C - they probably havent been serviced for a long time. The pressure gauge on the boiler always reads zero so guess it's not functional. The cut-in pressure setting on the pressuretrol seems to be at the lowest point (picture attached) and the cut-out wheel shows a "1" when viewed from the opening of the box.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    I think a 3C is for convectors, like a Hoffman 71C. That's pretty small for a main vent.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
  • jimb245
    jimb245 Member Posts: 6
    Thanks. Guess I need to get the vents and pressure checked.