Water Hammer

Jbaha14

Let me first say that this is a great site. I bought my home in August and went through (going through) my first winter season with steam heat that I can control. The previous home owners didn't do much of anything so when the first day of bitter cold and the house did not heat up the first thing I did was check the air vents based on Dan's book. Sure enough one was clogged. Not wanting to have to go from room to room searching for the problem I replaced all of the air vents. Then I undertook the task of insulating all my pipes and then installed a new Honeywell Vision Pro 8000. The house warms up nicely now.

My only problem is that I'm having some water hammer and it seems to be coming right from the radiator in my bedroom. I looked at it the other day and there is a rust line running down the supply valve, and upon closer look I saw steam coming out. This radiator also has a lot of hissing from the air vent. I believe that there is a small space where air is entering the radiator right at the stem of the valve and this is causing my problem.

I wanted to see if anybody knew of a way to fix this for now before calling in a pro and having them replace the supply valve. Will a rubber gasket work there?

I've attached a pic of the valve so you can see the rust line.

Thank you to all who can help me with this problem and have helped me this past season. My wife now wants me to join Steam Heaters Anonymous because I can't stop reading about how these systems work.

Jason

michael_15

You can tighten the nut

Tighten the nut on the valve stem. If that doesn't work or it's already pretty tight, then you'll want to re-pack it. Use graphite packing, which you can buy at a supply house. Unscrew the nut, stuff it with a little bit of the packing (or wrap the packing around the stem, if you prefer), and then re-tighten it.

Air won't generally enter the radiator through the leak since there is positive pressure in the radiators. Instead, steam comes out. (Except when the boiler is off and the steam is condensing away, of course.) I can't imagine how this would cause water hammer in your instance, however.

When does the water hammer happen? Mid-cycle? Is this radiator piped from the boiler differently (as in not sharing the main vent, for example)?

If the hammer is coming from the radiator, I'd check the pitch of the radiator first. Another thing to try is installing a smaller air vent -- if the air is venting fast enough to hiss, you may be forming too much condensate in the radiator, which can't escape because the steam is so busy rushing in.

-Michael