Single Pipe steam leak

MikeinNEPA

So recently I replaced a 19ft run from the main to the largest down stairs radiator Before being replaced the 90 degree elbow leaked and there was a bad water hammer in the pipe due to a sag in the middle of the run. I replaced it with a single length of 1 1/4" a 90 a short nipple and a new shut off valve(all from the local pluming supply shop no rolled black from the big boxes) and some strapping to prevent strapping. For a few months the run was fine, no leak, no water hammer. The only thing it did was as soon as the steam kicked on it would make a slight clunk sound, nothing like a water hammer, it was a very dull sound and very brief, and then it was silent, almost like it settling. boiler shows 3lbs but its an old 30psi ( I think) gauge and tough to read, the pressuretrol is at the lowest setting 1.5. Other things that might help there is a new brass adjustable value on there, that I generally keep almost fully closed as its the closest to the thermostat. I just had the boiler serviced in the fall and the plumber seemed to think everything was in order. When I installed it i used pipe dope on every connection and everything was quite tight, and everything is insulated. My main concern is that this is the same place as the old pipe leaked, which seems peculiar.

So if anyone has any idea's on whats the problem, and how to fix it, and if not would there be an adverse side effect to having someone weld the elbow on the pipe, to prevent further leaks.



Thanks for the help in advance.

Hap_Hazzard

Keep the valve all the way open.

On one-pipe steam, the valves should be either fully open or fully closed. If you want to slow down a radiator that's near the thermostat, use a slow vent.

Hap_Hazzard

Keep the valve all the way open.

On one-pipe steam, the valves should be either fully open or fully closed. If you want to slow down a radiator that's near the thermostat, use a slow vent.

MikeinNEPA

correction

I'm not throttling the shut off valve I'm talking about the little pressure release value on the end of the radiator i keep close to closed.

nicholas bonham-carter

New piping

I'm not sure I understand-is it now leaking again?

When you replaced the shutoff valve, di you also replace the spud into the radiator. They are a matched pair, and will not seal together for long.

If your gauge is difficult to read, then it is time for a 0-3 psi gauge graduated in ounces, so you can see what the system is doing (gauge store .com)--NBC

MikeinNEPA

Spud

I replaced both the value and the spud, the leak seems to be coming from below the floor, I don't have any water besides in the basement. When i was working all the little details out of the system after buying the house a new gauge was on the list but as things started to work out all the little issues i never got done.

icesailor

Leaks:

Unscrew everything from the valve to the pipe that the elbow is screwed on to. Re-do with Teflon Pipe tape and paste like Rectorseal #5 or the favorite like type, and do it over. The leak will stop. And you will see where the leak now is.

Be careful to NOT over tighten the fittings because with Teflon, they screw on with less resistance. On CI fittings, if it starts to get tight and you think you could go around again, and you do, the fitting will probably crack. In fact, you might have a cracked fitting now. With Malleable fittings, if you are turning and suddenly it starts to turn easily, you have stretched the fitting, it will leak, and must be replaced.

In other words, DON'T OVERTIGHTRN IT!!!

FWIW

Also, check the pitch on the line to the main from the riser. Make sure it pitches in the right direction. If the radiator is on the first floor, you may be able to put wedgies on the feet to raise it up.

MikeinNEPA

leaks

So is it best to replace the elbow right from the start, or just take it apart and see how it goes?

MikeinNEPA

another correction

So I started working and after taking the cover off I found that the drip does start at the spud/valve union, both are brand new. Now when I first felt it the union was loose so i cranked down on it and it slowed the drip quite a bit but its still leaking about one drop per min. The reason I missed it is that the water ran along the pipe into the basement where it fell off the elbow below the floor, hence why I didn't have water upstairs.

I know originally the valve/spud union was tight as I could see my tool marks on the brass. So could it be a bad valve/spud combo or could something have caused it to loosen it self? what can I do to replace it and prevent it from happening in the future?

BobC

Check alignment

The spud/valve could be defective but look at the alignment between the radiator and valve first, also make sure it's not weeping from the spud/radiator joint. Make sure the radiator and spud are well lined up and use some pipe joint compound on the faces of the union and teflon tape on the threads.



Bob

icesailor

Tricks:

Something I always do.

When tightening a union, always paint the face of the union. Tighten as tight and as far as you can go by habd. It should turn easily. If it diesn't, take a pry bar with a board on the floor (so you don't damage the floor) and see if it will turn easier and get it on some more by have if you can. If you had to use a pry, use it again to turn the nut with a pipe wrench. Get it as snug as you can. Then really tivhten it. You want the union nut to pull the union face as colse to perfect alignment as possible. If you don;t, you might have more pressure on one part of the face than another. That can cause a leak.

If you cranked on the nut and found it loose, it wasn't tight enough at the start but it was probably misaligned.

MikeinNEPA

problem solved

So teflon and alittle left-right adjustment on the valve seemed to line everything up better, then found a second leak where the spud goes into the raditor. Took that out cleaned the inter threads with a wire brush and tefloned the spud now no leaks. Thanks to everyone for their help. You've saved me a lot of aggrivation.