Water hammer, no heat from one convector

narwhalicious

I have a single pipe steam system with working radiators all over the house except for one convector in the second floor bathroom, which also happens to be the most distant from the boiler. The convector never seems to heat up and it makes a terrible clanging noise that reverberates all the way down to the 1st floor steam pipes when the system cycles on.

The convector is recessed into the wall and very clearly pitched. I replaced all my air vents with new Hoffmans last winter, so those should be good too.

Any idea what might be wrong? As far as I know, there is no valve to adjust on this one.
Pics:
http://imgur.com/dq94UxX
http://i.imgur.com/PrVQsLa.jpg

When I first bought the house, there was a maid o mist vent and the convector was getting warm but panting like a creepy killer was hiding in the bathroom. The system got flooded at one point and I believe thats when this concector stopped working.

Any idea what the problem is? Is there a half open valve i can simply open all the way? Perhaps a messed up steam trap?

BobC

It sounds like you have water trapped in a horizontal pipe somewhere. Put a level on the pipe that connects this convector to the main and check it all pitches back towards the main so water can drain. Then stretch a string along the pipe in the basement to be sure there aren't any dips in the piping.

There should not be any traps in a single pipe steam system, are all the radiators single pipe? In the picture it almost looks like the short horizontal pipe under the sunrad is pitched wrong, maybe the pitch on that radiator is too much? If you try to move it be gentle, old pipes can be touchy.

Bob

narwhalicious

I would have to tear open the floor of my bathroom to do that, which I intend to do in about a year when I remodel it. Is there nothing else I can do to diagnose the problem until then?

KC_Jones

Can you trace the entire pipe run from basement all the way to the bathroom? You should check ever portion of the pipe you can see before you determine the floor needs ripped up. On a one pipe system all the pipes should slope away from the radiator. I agree with Bob the pipe directly under that convector looks suspect. It should be sloped towards the elbow coming out of the floor. If it isn't you might be able to lift both sides of the convector higher to achieve the slope you need. The clanging could be water hammer. The hammering is from steam encountering water and slamming the water into "something" so just because you hear it in the bathroom doesn't mean the real problem is there...it could be some distance away. The flooding does seem to point at some kind of water trap in the piping.

narwhalicious

Thanks KC, everything is all covered up, even in the basement (it was finished at some point).

Am I correct in understanding that there is a possibility the convector is pitched so much that it's pushing that exposed elbow down and water is pooling there?

If correcting the pitch of the convector does not work: I'm considering electric radiant for that bathroom when I remodel it, maybe it would be cheaper suffer through some clanging for a year and then put in the radiant/get rid of the convector?

narwhalicious

And thanks for introducing me to the term sunrad, not sure why I thought that was called a convector!

Bio

If the horizontal wood molding is level then your rad is tilting to the left and water is sitting on the bottom left, you need to bring that bottom left at least to level

Jamie Hall

Going back to the original post -- there are two clues there that say there is a section of pipe with a bad pitch: the clanging and the panting both indicate water pooling somewhere. The question is... where? Since all the other radiators are working, it would be most likely that the problem is in the lines from the steam main to this particular radiator.

Unfortunately, without being able to check each nearly horizontal piece of pipe (note: nearly horizontal!) it may be difficult to locate the problem, never mind fix it. Nor would it be simple to see if there is a half open valve on the line somewhere (don't laugh -- I've seen it) since all the piping is carefully hidden...

narwhalicious

Interesting, thank you for the insight!