I have to replace a leaky 1/2 inch cold water valve in my basement (I know
how to sweat the pipe/valve), and was told that I have to drain down the
water in my house before doing it (I have a furnace & hot water heater in
What is the best way/procedure for draining down the water? Is there a guide
on how to do this? I know bits and pieces on what to do, but would rather
get the full procedure. Thanks!
The water will remain in the boiler and hot water heater. That's not a
problem. You need to drain the water from the pipes because water can make
Turn off the water at the main valve and open a low faucet (outside bib
faucet, maybe) and a high faucet. Most of the water will drain out. Plan for
some water to spill out when you remove the old valve.
Sometimes it helps to add a wet/dry vacuum to the lowest point to get some
pockets of water that always seem to trickle down once you get the pipe hot,
only to cool it back down. I duct tape a piece of vinyl tube to the vacuum
hose crevice nozzle and then jamb fit and/or duct tape it to the pipe or
valve outlet. The clear vinyl tube allows one to see if water is still being
pulled from the pipe. Keep the high level valve open to let the air in.
Then there's the trick of pushing a ball of bread into the pipe before you
start sweating. The bread seals the pipe long enough to finish the
sweating, then dissolves and gets flushed out.
I've never done this myself, so it's up to you to decide whether you'll
screw up some valve down the line. Just to be safe, cut off the crusts. :-)
I've seen this mentioned. Would never try it. I can think of places that
ball of bread will do no good immediately like going to the washing
machine with screens in the hoses or to a frig that has an inline water
The bread trick works, I used it more times than I can remember.
Yes it MIGHT cause problems with with clogging screens & filters IF
you don't plan an exit path for the bread.
In the many times I've used the trick, I've never suffered a clog
because I left an open escape path for the bread; an open hose bib or
faucet with the aerator removed. When the water is turned back on,
the bread plug travels to the open point & is blown out.
Or if you're really worried just remove all the aerators & flush the
lines to each sink (IMO overkill since the single blow out point seems
to work fine)
and yes, cut off the crusts & use a cheap white bread.... most
"granola head" wheat, etc bread is too coarse to form a good
btw back in the 1920's & 30's, galv steel was the piping material of
choice.......CWT didn't become widely used until the late 50's / 60's
The OP mentioned the leaky valve is in the basement so an outside hose
bib would be too high to be the low vent. He probably has a laundry/
slop sink down there, and that's the faucet that should be opened up.
I usually open all faucets that are on that branch to speed draining
and so there are no surprises during sweating.
On Thu, 10 Jul 2008 09:23:09 -0700 (PDT), firstname.lastname@example.org
A few weeks ago I watched a plumber repair some pipes. He had
difficulty, because of the water remaining and was not able to sweat
Using a cordless drill, he drilled a small hole in the bottom of the
pipe, next to the valve. Water drained, and repairs made.
That was the first time I've seen such a trick.
And, on a completely different tack from the guys who got the draining
Where/what is leaking--the valve itself not holding or just a stem leak?
What kind of valve?
There's always the possibility of simply repairing it and avoid the
necessity of actually opening the piping itself entirely not to be
I would take this time to drain the hot water heater as well. YOu should do
that yearly anyway.
1. Turn off main water into house.
2. Put a hose on the heater and run it to a basement drain. Open the
heater drain valve.
3. Go upstairs and open some faucets hot and cold to let air into the
4. Wait until heater drains completely.
5. Open your leaky valve and let it drain.
all this is assuing the hot water heater drain valve is the lowest in the
house. The simple way is to turn off the main water, open the leaky valve,
and open another set of valves which are higher than the leaky one. It
should drain enough for you to solder it.
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