Vent-Rite No 51 adjustable steam radiator vent being disassembled (C) Daniel Friedman Steam Radiator Vent Cleaning & Testing
Steps in cleaning & testing: how to get the steam vent working or decide to replace it

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Steam radiator vent cleaning & testing procedures:

How to remove, clean, then test a steam vent to either get it working or decide that it needs to be replaced. This article describes step by step how to remove, clean, de-scale, then test a steam vent used on radiators or on steam main piping systems.

We include warnings that may help avoid trouble and we explain how to determine that the steam vent should simply be replaced.

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Steam Radiator Vent Cleaning

A steam vent is designed to allow air to escape from the steam piping or steam radiator during the heating phase (when steam is rising in the system), in order to allow steam to rise into the piping or into the radiator itself.

If the steam vent becomes debris clogged or otherwise is not working it cannot vent air properly. Results of a clogged steam radiator vent or mainline steam vent include loss of heat, diminished heat, cold steam radiators, or sometimes a steam vent that does not stop venting when it should, continuing to vent steam even after the radiator is hot.

Manufacturers such as Heat-Timer Inc. (producer of the Varivalve quick vent discussed at STEAM VENTS, AUTOMATIC) point out that

... Over long working hours and years, these air vents clog with rust from the radiator and other heating system components. In many cases, it may be a matter of cleaning the air vent to bring the radiator back to its working condition. Cleaning the air vent is a very simple process that can be done by any homeowner. - retrieved 22 Jan 2015, original source: Steam Vent FAQs, : Heat-Timer Corporation, 20 New Dutch Lane Fairfield, NJ 07004 USA, Tel: 973 575 4004 and website:

The following steps in cleaning a steam vent are adapted and expanded from the information we just cited:

  1. Turn off the heating system and allow it to cool so that when you remove the steam vent you don't send potentially dangerous scalding steam venting into the occupied building spaces.
  2. Remove the steam vent from the radiator using a suitable wrench.
    Watch out: don't use a larger wrench than necessary and still if you cannot remove the steam vent with just modest turning force (counter-clockwise) STOP lest you break off the vent and have to leave your heating system shut down while waiting for your heating service technician to bail you out.
  3. Soak the steam vent in household vinegar for 30 minutes or longer if necessary. If there is visible white mineral scale on the vent that disappears or that will disappear when you agitate the vent in the vinegar you've probably soaked it long enough. Notice that for this procedure you are not actually disassembling the vent into its individual components though if that's necessary we show how to do so beginning at STEAM RADIATOR VENT REPAIR.
  4. Rinse the steam vent thoroughly with cold water.
  5. Test the steam vent by blowing through it: (blow into the end that screws into the radiator body)
    1. If the steam vent is clear: if you can blow through the steam vent and air comes out of the vent's exit orifice freely then the vent is as clean as you'll get it without disassembly.
    2. If the steam vent is not clear: if you can't get air to move freely through the steam vent try shaking it and rinsing it again. If you still can't get air to move through the vent you can try soaking it longer and repeating the rinse and blow test above.
    3. If you cannot clear the steam vent your options are to risk ruining it by disassembly (shown above) or just buy a new replacement steam vent of the same type and capacity.
  6. Re-install the steam vent (or install the new one you bought after cleaning didn't work). Wrap the threaded end of the vent with teflon tape, taking care that the tape doesn't block the steam entry port on its mounting end and screw it back into its tapped mounting opening on the steam radiator.
    Watch out: be sure that you end up with the steam vent pointing "up" for proper steam vent operation
  7. Turn the heating boiler back on and set the room thermostat to above room temperature so that the boiler operates and sends steam rising in the system.
  8. Watch the steam vent for proper operation: as steam rises in the system the vent should release air in the piping or radiator. When the radiator (and the steam vent itself) become hot the steam vent should close. If the steam vent does not close - that is if it continues to vent steam, replace it.

Bottom line on steam radiator vent repair versus replacement

If you are a tinkerer or if you are desperate to try to get a recalcitrant steam vent working and don't have a replacement at hand (replacement is still our best advice), you might want to try disassembling the steam vent and then cleaning the valve seat or float pin in a steam radiator vent.

Details of how to do this steam vent disassembly are

But really for most repair technicians or building occupants or owners you'd be better off just replacing the steam valve if simple cleaning (described
at STEAM RADIATOR VENT CLEAN & TEST did not work) didn't work: it's often not worth the time and trouble to actually disassemble the steam vent, especially since there's a good chance that if the valve no longer opens or closes when it should it's the float itself that's at fault.

Given the trouble of cleaning and reassembling and reinstalling the valve, then bringing up the heat to watch the valve to see if it works, the disappointment when it doesn't, and the muttering, to me it makes sense to just go ahead and replace the steam vent with a new unit.


Continue reading at STEAM RADIATOR VENT REPAIR for details about how to completely disassemble a steam vent, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

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STEAM RADIATOR VENT CLEAN & TEST at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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