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I need to fix some leaky return shutoff valves on a hydronic heating system. Is there such a thing as an inflatable device that can be used to plug the pipe to prevent the system from draining while the washer is being replaced?

return valve closeup

mr blint
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  • I've heard of people stuffing a slice of bread into the pipe. Seems like a really bad idea, though. – Daniel Griscom Dec 23 '16 at 13:26
  • That trick's for domestic water, I think, and it's usually a small ball that will dissolve. This is large black-iron pipe. I'd have to stuff a dinner roll :) – mr blint Dec 23 '16 at 13:30
  • ... this is a hot water (heating) pipe, right? Use dough, and it will leaven and fill the pipe. Then you'll be left with an unusual cylindrical loaf. (Could be marketable...) – Daniel Griscom Dec 23 '16 at 13:38

2 Answers2

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If you can stop the flow of water in the system you can freeze the water in the pipe, then fix whatever you have to. This works on steel and copper pipe. I have frozen pipes up to 2 inches. A pipe freezing kit is great but you can also use dry ice. Find a place that sells dry ice and buy the crushed type. Make sure you use heavy gloves to protect your hands. Get a face towel or equivalent and use it to hold the dry ice as you wrap it around the pipe. Use a lot- 2to3 inches of ice. Then duct tape the cloth to keep it in place. Wrap this whole thing with paper towels or newspaper for insulation and wait for the pipe to frost up just past the dry ice wrap. Test for water stoppage downstream. When frozen you can complete your repairs. When done remove everything, allow to thaw and you are done. And by the way where is the washer in a hydronic heating valve? all the ones I have seen have brass to brass seats.

d.george
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  • Thanks for the dry-ice tip. I just assumed there would be something like a Viton washer inside. All I know is that it's dripping :) It is nominal 1.25 inch black-iron pipe. The O.D. is 1.66" – mr blint Dec 23 '16 at 11:54
  • Where is the drip coming from, a valve stem, pipe fitting, pipe union, etc. If the leak is at the valve stem you can sometimes add packing at the stem. – d.george Dec 24 '16 at 12:46
  • It is coming from the valve stem. What kind of packing? I have some oakum left over from a plumbing repair on an old lead-sealed waste pipe toilet flange. – mr blint Dec 24 '16 at 13:18
  • Is there a packing nut where the leak is coming from? If so, loosen the nut all the way and slide it up the stem. Add a few wraps of packing, slide the nut back down and tighten the nut hand tight . Slowly tighten the nut until the leak stops. You can buy packing at a local hardware store, Home Depot, Lowes. buy thin packing, 1/8 inch or less or as available. Wrap the new packing clockwise around the stem. You can use almost any type of packing; graphite, silicone, I have even used pipe Teflon tape looped together and twisted into a string when I could not find any thing else. – d.george Dec 26 '16 at 11:37
  • Don't use the oakum. – d.george Dec 26 '16 at 11:39
  • It seems to be dripping from the handle side of the packing nut, along the stem. Is the packing applied clockwise when facing the valve from the stopper side or from the multi-turn-handle side? – mr blint Dec 26 '16 at 13:04
  • looking down at the stem,from the handle to the pipe,wrap the packing clockwise or the same way as when you tighten the packing nut. – d.george Dec 28 '16 at 10:39
  • Is this repacking done with the valve fully closed ? – mr blint Dec 28 '16 at 12:19
  • I would install the packing with the valve midway but it should not matter. 2 or 3 wraps should be enough. You can always add more. By the way what kind of system is this steam or water and what kind of valve? – d.george Dec 30 '16 at 11:54
  • It is the main return on a heating system (hot water with convector-fin style radiators). The pipe this valve is on is nominal 1.25" black iron pipe. I will let the system cool down before working on it. When I back the packing nut off, the system will begin to drain if the valve isn't shutt. I can catch the water in a bucket but I try to avoid that, as refilling with fresh water increases chances of a leak. It's 75 years old. Graphite impregnated packing is 3/32 diameter and the teflon packing is 5/32. Would the larger diameter be the right choice for such a large valve? – mr blint Dec 30 '16 at 13:04
  • Not sure of the kind of valve. Multi-turn shutoff. I could add a picture if that would help. – mr blint Dec 30 '16 at 13:06
  • I am getting curious now , Add a picture.the system should not drain unless this a drain valve. Show a picture of the valve and a picture of the connected piping. – d.george Dec 30 '16 at 14:50
  • Pics added. I guess I should have said that my CONCERN is that the system will start to drain if I try to repack the valve with the valve partly open. I haven't it yet (it's cold here at the moment and I'm waiting for a warmer day to do this). – mr blint Dec 30 '16 at 15:04
  • Show more pictures of the piping so I can see what this valve is for. I can't understand why the system will drain when the valve is opened. – d.george Dec 30 '16 at 17:02
  • Let us continue this discussion in chat. – d.george Dec 30 '16 at 17:45
  • The packing must fit inside the packing nut, so I would use the larger packing if it fits under the packing nut, if not use the smaller. Also in your Dec 30' 16 at 15:04 you said that if you open the valve to repack it the system would start to drain. That does not look like a drain valve. A wider picture would be helpful. – d.george Jan 06 '17 at 10:59
  • I don't have much experience with valves, and my fear was that if I loosened the nut, the stem of the valve would come out of its seat and the system would start to drain. These are return shutoffs. They feed back into the boiler. I will pack as you say. Thanks. I have learned something new. – mr blint Jan 06 '17 at 12:14
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There are all kinds of temporary pipe plugging options, inflatable, mechanical, etc. Here is a link to one supplier (not an endorsement of products) Pipe Plugs and Stoppers

Jimmy Fix-it
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