Steam leak from valve bonnet

Fizz

One pipe rad valve has slight leak. Is replacement only remedy?

KC_Jones

Need to see a picture of valve. As long as nothing is cracked or broken I advocate for repair rather than replacement. I know there are varying opinions on that.

Jamie Hall

KC_Jones said:

Need to see a picture of valve. As long as nothing is cracked or broken I advocate for repair rather than replacement. I know there are varying opinions on that.

Totally agree. Please post a picture of the valve and, if possible, indicate exactly where the leak originates. That sort of leak is almost always repairable, but the repair is different for different places or different valves.

Fizz

Here's pic, hope it helps. Steam comes from left side of valve bonnet.

nicholas bonham-carter

Also check your pressure to make sure it has not crept up because of a plugged pigtail.
Old valves can be repacked with graphite or Teflon string, I think there is a video here of that simple procedure.
Changing the valve involves removing and replacing the valve spud from the radiator, which can be very difficult. A new valve can be of a slightly different size, and may be of lower quality than the original.—NBC

Jamie Hall

You're in luck. That's an easy problem to fix. As @nicholas bonham-carter said, there are videos on how to go about repacking such a valve. Matter of turning the boiler off, unscrewing that bonnet nut (which you have the Teflon tape on) replacing the packing around the valve stem, and screwing the whole thing back together.

KC_Jones

Jamie Hall said:

You're in luck. That's an easy problem to fix. As @nicholas bonham-carter said, there are videos on how to go about repacking such a valve. Matter of turning the boiler off, unscrewing that bonnet nut (which you have the Teflon tape on) replacing the packing around the valve stem, and screwing the whole thing back together.

Also do not put teflon tape back where it is now, those threads should have nothing applied to them. The packing does all the sealing.

Fizz

The leak is at bonnet and housing, not the stem. Leak seems to occur towards end of cycle, so it may have to do rise in pressure. I replaced Gorton 5 vent with MOM4, hoping to slow-down steam to rad somewhat.

Jamie Hall

That bonnet assembly should also be removable. You may have to encourage it... use a good big crescent wrench on the square flats, and you may want to put a backup wrench on the hex at the bottom. If you can get it apart, clean the faces well; it should seal without any sealant, but a THIN smear of red RTV will get it sealed. THIN! You don't want it gooping out, particularly inside.

Fred

I am almost certain the bonnet leaks due to steam pressure. What is the Pressuretrol set at and has the pigtail been cleaned lately?
Does it actually leak steam or just weeps a little water?

Fizz

Pressuretrol set at cut-in 0.5, and out 1.0. New pigtail installed 7/2017.
Yes, steam no water.

Fizz

Jaimie, would tightening it help, or just remove, clean and replace?

Jamie Hall

Try tightening it -- but if you're going to put a wrench on it, you might just as well do the whole thing... But give it a twist first. If that works, be happy!

Fizz

Thanks Jaimie and Fred.

Fred

Fizz said:

Pressuretrol set at cut-in 0.5, and out 1.0. New pigtail installed 7/2017.
Yes, steam no water.

Check that Pigtail ....

Fizz

Ok, thanks Fred!