I noticed a shut off valve that goes to the bath tub was leaking, so I decided to replace it. I shut off the hot water coming out of the water heater, and drained the water and attempted to solder a new valve in. The problem is, a little bit of water keeps coming out from the hot water side, and it is stopping me from being able to solder the copper pipes. Water in pipes are very hard to solder. I am thinking the valve before the one I am fixing is slightly defective and letting a little bit of water pass by. One Idea I had was to drain the water heater, that way all the water is out of the pipes, and try to solder again. Does anyone have any experience on this?
The draining the water heater solution may work. Another option is to simply turn off your house's main water supply. It is usually right there with the water meter. Even if that isn't 100% tight (and it should be), combining the effects of turning off the individual stops and the main stop should slow flow enough that you can get the pipes empty enough, for long enough, to get your joints made. Been there! Good luck with it.
Stuff a piece of bread into the pipe before you solder. The bread will stop the water long enough to solder the pipe and the water will dissolve the bread when you turn the water back on
Mike deserves best answer, that is an old plumbers trick. Turn the tub faucet on when your done. If it was a sink you were repairing the bread could clog the aerator, which is no big deal. But being the tub, you'll have no issue with an aerator.
