Radiator slow drip at the union of the shutoff valve

Tuggy

I've recently noticed my boiler LWC kicking in once/2 or 3 days and the feeder being activated for about 8 seconds and I began checking for leaks at the 19 radiators throughout the 3 floor house. The house is >100 y.o. and originally had a coal fired boiler before transitioning to oil ages before I was around, but the piping system (and I assume) the radiators are mostly unchanged (they're old regardless).

So far I discovered one of the two radiators in the bedroom of FL2 where the vent isn't shutting during a cycle when it's piping hot, hissing and letting some steam escape. This BR is at the rear of the house which gets more of the steam faster as the boiler is situated more towards the rear. The vent is a MoM4. No issue with addressing that.

THEN I NOTICED that same radiator has a slow drip at its' union.

The water seems to originate on the supply-side and it's about 1 drop/8 seconds or so at boiler full throttle/mid cycle.

Is this a difficult fix? What are my options here?

Last year I discovered several of the radiators on Fl 3 had slow drips coming from the stem of the shutoff valves. These radiators are of the recessed type:

I was able to remediate this myself by cranking on the packing nut ¼-½ turn on these:

and that stopped those leaks, albeit it was very difficult to do because there's nearly zero clearance to turn a wrench because of the constraints of the design. I imagine it'd be a significant job if the shut valve need to be replaced on these.

Nevertheless, the radiator in question on FL 2 is of the very common free standing type so things are much more accessible and workable here, but I don't know what's the general remedy for the leak I am facing now.

Appreciate any advice and suggestions, YT vids that might be apropos to my situation that a non-pro might be able to tackle on his own.

TIA

(ps Thank you site owners for auto-save & drafts here! phew!)

Jamie Hall

That drip is enough to account for most, if not all, of your water loss. Surprising how they add up.

Now. A quick review of how a union works. The actual seal is on a pair of mating surfaces behind that big nut. The two surfaces — one on the valve and one on the pipe (called a spud) coming out of the radiator — must mate very exactly to prevent a leak.

So. What you need to do is first turn off the valve. You don't want to get steam all over the place! Then loosen that big nut. If you imagine yourself sitting on the radiator, it will unscrew counterclockwise. If possible, use a big crescent wrench, not a pipe wrench, to avoid scarring it. It should unscrew completely and be caught on the spud. Now the fun part. You need to separate the spud from the valve, so you can clean the two mating surfaces. Whatever works. Clean the surfaces with something like the rough side of a dish sponge — never ever use sandpaper or anything abrasive! When you're happy and the surfaces are bright and shiny, push the radiator over so they are firmly seated. A union will not take up lateral or angular alignment problems, so make sure that the final alignment is perfect. Then hand tighten the unit nut and give it no more than a half turn more.

Good luck!

Tuggy

Excellent tutorial!

 If you imagine yourself sitting on the radiator, it will unscrew counterclockwise

So this is reverse of normal thread? So if I am in on my knees in front of it from the same perspective that my photo above was taken from, I would push the wrench toward the wall, to loosen it, correct?

And when I loosen it, no need to "hold back" with another wrench any of the other sides/pipes?

*and no tape/dop on this thread when I reconnect, yeah?

Jamie Hall

Actually, it is a normal thread — but what is confusing is that the male thread is on the valve. Up and towards the wall should do it. You shouldn't need a backup unless the union was attacked by a gorilla, but do hold the riser and valve steady one way or another.

And no, you don't need pipe dope, although some folks like to put a VERY thin smear of it on the mating faces of the union. The seal is on those mating faces, not on the threads.