01 of 05
Troubleshooting Steam Radiators and Air Valves
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... are easy to fix.Continue to 2 of 5 below.
02 of 05
Air Valve Makes a Gurgling Noise
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... approximately 1 inch for every 10 feet of radiator length. If your air valve is making a gurgling sound, check for the following conditions:
Continue to 3 of 5 below.
- 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.
03 of 05
Air Valve Constantly Hisses
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.Continue to 4 of 5 below.
04 of 05
Radiator Does Not Get Hot
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:
Continue to 5 of 5 below.
- 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... 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.
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.