I was experiencing a problem with my water heater which is in my basement. I disconnected and temporarily capped the cold water input pipe. When I turned on the main water supply, I could hear water running into the water heater. I turned the water off again and disconnected the hot water side pipe. I placed a catch pan underneath the open pipe which is the outlet pipe for the hot side of the water heater. When I turned on the main water supply to the house again, water began to run out the pipe. The water was not pressured as it would be if the piping was somehow installed wrong but was a steady stream. All the faucets in the house were turned off. I have 2 Delta single handle shower valves, one of which has recently been replaced.

Hi Homeowner

A mixing cartridge has failed at one of your single handle faucets/valves. You have to isolate each faucet/valve by using shutoffs or capping lines to finds which valve it is (or isn't... read on).

You could also have a failed washing machine solonoid valve... shut off shutoffs to the hoses feeding the washing machine to eliminate this as the culprit.

Anything else that can mix the water... outside faucet with hot and cold supplies tied together... other stuff like that, OK?

Glad to discuss more if you want...

Mark

OK. I have also turned off the cold water supply to all of the sinks in the house and the washer. So I think the showers, which have no separate cut-off valves must be the problem.

Cap the line to the oldest valve first, or just replace the cartridge to the oldest valve, but be sure to pick up the second cartridge just in case it is the newer valve... can always return the cartridge if not used.

You said it's a Delta brand... the cartridge(s) may even be under warranty.. right?

If I do have cross flow across one of the shower valves, would that in any way damage my water heater? My originally recognized problem with the water heater was that I had hot water for a short while and then the water would become only warm not really hot. I diagnosed this problem as a dip tube issue and when I inspected the tube, I found that this was indeed the case. When I was working on that issue, I noticed there was a small amount of water at the top of the heater that had wet the insulation. I can't really tell where the water is coming from. I am OK with replacing the water heater if that is the case, but was wondering if the heater might have a back flow preventor or something that would release backflow. The pressure relief valve is functioning OK.
I cannot cap off the pipes directly into or out of the showers tonight as they have 1/2 feeder lines and all the plumbing supplies I have are 3/4. I do have a 3/4 gate valve that I can install on the hot water pipe so that I can turn my main water back on tonight.

Water heaters have no backflow device (unless you have HEAT TRAP NIPPLES.. if so, replace these with dielectric nipples, or if you have a CHECK VALVE... could be stuck open) so that's not it.

Sounds to me like you did everything right but in shutting things down and turning things back on something messed up at a mixing cartridge... replace them and you should be all set!

*crossing fingers*

Let me know what happens tomorrow, OK?

Mark

Thanks for your help. I'll have to wait until Monday to look at this problem again. I'm spending the next 3 days starting the process of cleaning out my recently deceased mother's house. Joy comes in multiples!
Right now I have the water heater out of the water circuit with both input and outlet pipes sealed. I turned the main water supply back on and nothing is leaking-thank goodness. So now I can wash the many towels that I have gotten wet in this whole process-in cold water.

Sorry to hear about your Mother... always sucks!

I'm here if you want to discuss more, OK?


Mark