Removing Sweat Valve

Old 04-15-08, 09:29 PM
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Removing Sweat Valve

I've got about 20 year old copper piping with a sweat valve. I moved my toilet for the purpose of tiling and ending up breaking the knob from the multi-turn valve. I want to replace the valve without having to cut the pipe. Bottom line: can I use a torch to desolder the pipe, put another valve on and solder that back? Any help would be appreciated.
Old 04-15-08, 11:19 PM
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Yes, just be sure and try and get the old solder off as much as possible (I've heated & wiped with damp rag, with reasonable success), then clean it up good with sandpaper before sweating the new valve on.
Old 04-16-08, 12:43 AM
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Use a 100% cotton rag to wipe the melted solder from the end of the pipe. Don't wet it but wad it up to keep a large amount of rag between the pipe and your fingers.

If you use a synthetic or blend rag you will end up really frustrated and hopping mad.
Old 04-16-08, 06:30 AM
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Try to drain the pipe as much as possible (turn off main supply, and open some faucets on a lower floor - then open the valve in question if possible to allow the water to siphon downwards). Otherwise, you're just trying to boil water in the pipe and it won't get hot enough for the solder to melt, allowing you to pull off the valve assembly. While applying heat, gently, but firmly put a twisting pressure on the valve (channel locks) until it begins to turn - then slowly, carefully, work it off the pipe. I say this because it's easy to bend/distort the copper piping when it gets to temp as you try to take off that valve.
Old 04-16-08, 06:19 PM
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Hi, I'm a little superstious. When you remove the valve install a threaded adapter then screw in the new angle stop. With this system it will probably never give you any further problem but if it does all you have to do is shut off the water and unscrew the valve.
Good Luck Woodbutcher
Old 04-20-08, 07:57 AM
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Sorry to semi-hijack this thread, but ...

I also am in an old house. I find that the old copper pipe is much harder to sweat a good joint on than new stuff. Is that common? Reason? I am very careful about cleaning the old pipe, use good flux, etc.

This could further mitigate for the new fitting rather than sweating.
Old 05-14-08, 04:22 PM
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Am I just imagining this, but I seem to recall my father using STEEL WOOL to wipe off the old solder once he had remove a old fitting?

Dale in Indy
Old 05-14-08, 06:37 PM
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First off you will need to disassemble the shut off valve (remove handle, remove nut behind handle, turn valve handle out. If handle is broken use pliers or vice grips), so you can get all the water out. That is of course after you shut off the house main and drain down as much water as possible. If you have a bathroom or faucet below the toilet in question open them to drain down. It may also help to open faucets on the floor above if any otherwise it will hold water like putting your finger on the end of a straw. Then it will drip slowly and sometimes it can make like miserable when trying to re solder.

Then you need to be very careful to watch your torch at all times. It is very easy to burn the wall when not paying attention.

Heat the valve on the chrome extension tube if it has one. Keep moving the heat around. Keep pliers on valve and constantly try to twist it off.

BE CAREFUL not to over heat it as it will not come off if too hot. If you think you have gotten it too hot, let it cool back down then try again. Make sure to wipe off all the solder you can as mentioned in earlier threads. Then sand as clean as possible. Make sure you use a soldering flux or solder will not stick.

If you care what it looks like either re solder a new valve on or use a compression angle stop with escutcheon.
do not just solder on a threaded adapter if you care what it looks like. If you choose to use a compression stop you will need to make sure and clean the pipe extra good and will possibly need to cut to length.

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