Steam Radiator and Air Valve Repair

  • 01 of 05

    Troubleshooting Steam Radiators and Air Valves

    Wide angle image of cast iron radiator.
    Cast iron radiator for steam heat. Alan LagaduCollection:E+/Getty Images

    The air valve, or air vent, on a steam radiator allows air in the cooled radiator to be pushed our by incoming steam at the start of each heating cycle. The hissing sound of the air venting from the valve is a sign of normal operation but should stop once the radiator comes up to temperature and the valve closes, thereby retaining steam in the radiator. If your air valve doesn't sound right or your radiator isn't heating properly, it can be caused by a number of problems, many of which...MORE are easy to fix. 

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  • 02 of 05

    Air Valve Makes a Gurgling Noise

    steam radiator air valves
    Three common types of radiator air valves. © Home-Cost.com 2011

    An air valve making a gurgling noise can indicate a problem with the valve itself or with the radiator. In one-pipe steam systems, the same pipes are shared by both the steam supplying the radiators and the condensate, the cooled water returning from the radiator to the boiler via gravity. That's why each radiator's supply valve must always be fully open and the radiator must be pitched, or sloped. toward the supply valve so the condensate can drain back. A correct pitch is 1-in-10, or...MORE approximately 1 inch for every 10 feet of radiator length. If your air valve is making a gurgling sound, check for the following conditions:

    • Supply valve is partially closed. Make sure the supply valve is fully open (turned counterclockwise all the way).
    • Supply valve is corroded or broken and the valve seat is not opening fully or at all. Check for proper operation.
    • Radiator is sloped too little. It should slope slightly toward the end of the radiator with the supply valve and pipe. Shim under the feet of the radiator as needed to achieve a proper pitch of 1 inch for every 10 feet toward the supply valve.
    • Radiator is sloped too much. This can cause sediment to flow into the supply valve and partially obstruct the valve opening. If that has happened you must remove and flush the radiator.
    • Air vent is improperly installed. It must be positioned vertically. Make sure it is not installed upside down, diagonally, or sideways.
    • Air vent is partially obstructed with mineral deposits or other debris. Try to clean the valve with vinegar. If the valve does not open and close after cleaning, replace the valve.

     

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  • 03 of 05

    Air Valve Constantly Hisses

    Air valves should stop hissing partway through the heating cycle. © Home-Cost.com 2011

    A constant hissing sound throughout the heating cycle usually means the air valve is not closing and is failing to trap the steam inside the radiator. Try to clean the valve with vinegar. If that doesn't solve the problem, replace the valve.

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  • 04 of 05

    Radiator Does Not Get Hot

    steam air valve
    Air valves are located at the opposite end of the radiator to the supply valve. © Home-Cost.com 2011

    If the radiator doesn't heat up, it could indicate that the air valve is stuck shut, retaining cold air in the radiator and preventing steam from entering. Try to clean the valve with vinegar, or simply replace the valve. Also check for a few other conditions: 

    • Radiator supply valve is shut. Make sure the supply valve is fully open (turned counterclockwise all the way).
    • Thermostat in the room (as applicable) is set too low. Confirm that the thermostat is set above the room temperature.
    • Radiator...MORE is sloped too little. It should slope slightly toward the end of the radiator with the supply valve and pipe. Shim under the feet of the radiator as needed to achieve a proper pitch of 1 inch for every 10 feet toward the supply valve.
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  • 05 of 05

    Air Valve Spitting or Leaking Water

    An air valve that's spitting or leaking water may be partially obstructed with mineral deposits or other debris. Try to clean the valve with vinegar. If that doesn't solve the problem, replace the valve.