Radiator Still Leaking After Repair

TAC77

Hello,
I have a single pipe steam radiator system in my 1927 house. Last year I noticed that two of my radiators were leaking from the union joint. The one in the dining room would fill a small tupperware container while I was at work or overnight and would also soak through a dishtowel and washcloth I placed under the container. The leaking radiator in one of my bedrooms was a bit more sporadic; I would sometimes have an inch or so of water in the container and sometimes wouldn't have any. I tried tightening the nuts last year but it did not stop the leaks. I would have to top off my boiler with water every 2-3 days.

This year my boyfriend and I disconnected the radiators from the pipe that comes up through the floor and applied pipe dope to the threads, tightened the union nuts, and made sure that the radiators were slightly off-level and sloping towards the floor pipe. I let the pipe dope dry for over 24 hours before turning the heating system on for the first time this year. Our repairs did not help. Within an hour or so the containers had water in them and needed to be emptied after only a few hours.

Any thoughts on what else could be wrong? I'm wondering if we used too much pipe dope (we put on a generous amount) which is interfering with the seal it is supposed to create or if he did not move the radiator completely into the pipe. The last one seems unlikely because when I tried to finger tighten the nut it moved evenly and fairly easily over the threads.

Thanks!

mattmia2

Pipe dope won't do much for a union like that other than to make it easier to tighten and loosen the nut. The seal is made with a taper that the nut pulls together. It takes a lot of force to tighten a union that large, like probably a pair of 18" pipe wrenches or bigger. You can also cheat by wrapping teflon tape around the side with the nut so about half of it laps over the taper and it gets compressed between the 2 tapers when you tighten the nut.

TAC77

We did use a pipe wrench to tighten it but how would we use two?

nicholas bonham-carter

Make sure the mating faces of the union are clean and dry. Lubricate the faces with a bit of dish washing liquid.
Rock the radiator as you tighten the Union nut. That should help the two halves to unite and seal.
Pipe dope and tape will not work in a union, and only make things worse.—NBC

acwagner

Do the valves look like the rest of the valves in the house, or do they look like someone replaced them? If they look different, it's possible someone replaced the valve but not the mating spud in the radiator.

Otherwise, I agree that you'll need a large wrench--18" or larger to really tighten it properly.

HVACNUT

When tightening a union, 2 wrenches are needed. One to tighten CW. The other to hold the pipe from twisting while you tighten. Opposing forces.

TAC77

acwagner said:

Do the valves look like the rest of the valves in the house, or do they look like someone replaced them? If they look different, it's possible someone replaced the valve but not the mating spud in the radiator.

Otherwise, I agree that you'll need a large wrench--18" or larger to really tighten it properly.

Yes, the valves look like the others in the house; in fact, they look original.

Steamhead

If the above doesn't help, the valve bodies may be cracked. In that case you need to replace the valves. This is a job for a pro with the tools and know-how.

Where are you located?

TAC77

Steamhead said:

If the above doesn't help, the valve bodies may be cracked. In that case you need to replace the valves. This is a job for a pro with the tools and know-how.

Where are you located?

I'm near Cleveland.

Where do I look to determine if there is a crack in the valve body?

Intplm.

TAC77 said:

Steamhead said:

If the above doesn't help, the valve bodies may be cracked. In that case you need to replace the valves. This is a job for a pro with the tools and know-how.

Where are you located?

I'm near Cleveland.

Where do I look to determine if there is a crack in the valve body?

You have to look closely. Very closely. The water can ride or trail horizontally a few inches before it drips at the union nut which is the lowest horizontal point of that area.
If the the teflon tape and pipe joint compound doesn't work. You might need to tighten the nut further. One wrench is not enough.
Use one wrench to tighten the nut while using another wrench as a counter or backer to counter the force of the tightening wrench. Similar to what @HVACNUT said.

If all the advice here and ^^^^^hasn't worked you probably need to change the valve and the spud that is screwed into the radiator. These two parts are integral and sold together, and must be installed together to ensure a proper joint.

JUGHNE

The weakest link in your valve is the large union ring that you unscrew. Or in any union for that matter.....anyway it is the first part I break. It is brass and can get a small crack that is hard to see. If cracked it is new valve and spud time. Both must be changed as Intplm said. And unless you are really handy and adventurous it is best to higher it done as Steamhead said.
They must change both parts.

To find the small seeping leak I wrap strips of thin cotton rag around each suspicious part. The water that leaks in one place and seeps to a different part is captured by the rag. Process of elimination.

TAC77

Thanks for all the tips!

We re-tightend the union nuts and it seemed to have helped to an extent. The bedroom radiator hasn't leaked since I turned the system back on yesterday evening, although I still want to watch it because it would go long periods without leaking last year. The dining room radiator leaked a full container of water within an hour or so of the union nut being re-tightened. However, after that it has barely leaked even though I turned the heat up last night before going to bed.

Any ideas on why I would see so much up and down in the amounts of water leaking? Does it sound like I'm getting closer to getting the radiators to work right or is this typically what leaking radiators do?

JUGHNE

Often when any union that is reassembled gets hot it will drip.
I add another nudge of tightness when the fittings are actually hot. Tapping the flats of the nut with a small hammer while wrenching may help......easy taps as this is brass.
Don't burn your hands.

ScottSecor

Since our customers don't want to pay us twice to fix a leaking radiator (or any other component for that matter), we try to make the most reliable repairs the first time. Often they take a morning or afternoon off from work and cannot afford to have us come back. In most cases, we've found that if the radiator angle stop is leaking it is actually less expensive to replace it with a high quality replacement. This is not a cheap or easy fix and often requires a three or four foot pipe wrench to get the old spud out of a hundred year old radiator. We've seen many "ringed out" unions on radiator valves. These brass pieces can get out of round pretty easily when a three hundred pound radiator is sinking into the floor for a century. We've also seen the spuds crack, likely from the same tensions for years.

I am not suggesting repacking a radiator valve stem or trying to seal an imperfect union is a waste of time. In my business the results are not as reliable as simply replacing the entire radiator angle stop.

With regard to water leaking different amounts, my guess is it depends on how long the boiler actually fires during the 24 hour period.

Steamer1928

I've encountered something similar on one of my radiators only to discover that the leak was actually coming from the bottom-most point on the radiator where the first two sections join. The condensate would leak down to the radiator connection which made it seem like the valve or union was the issue. After replacing the valve and spud, I didn't understand why it kept leaking. So I have JB Weld on there right now, but what I really need to do is replace the 95 year old radiator.