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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

  • 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 :) – TRomano 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
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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

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    I'm still waiting for a reason to buy a Pipe Freezing Kit, but at $500 it might be a while. – Mazura Dec 23 '16 at 2:59
  • @Mazura there are also single use freezing kits. I've never needed one myself but I'm told they work quite well (but keep a spare to hand in case it takes longer than expected l – Chris H Dec 23 '16 at 10:59
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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.

  • 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" – TRomano 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. – TRomano 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

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