Help weird hot water problem

Dear Forum readers you have helped me int he past and hope ypu can help this DIY'er again.

I spent the weekend gutting my upstairs bathroom (4 piece) and installed a new Delta Shower/tub faucet. During the weekend my wife needed to use hot water and she realized there was no hot water in kitchen nor my other bathroom upstairs (MBR). I figured I needed to flush lines which were not done yet. I flushed the new faucet (from tub spout) and no surprise ...hot water......put my stop back on the tub spout and continued only to find out that the hot water goes to the other fuacets ONLY when the water is running in the newly installed faucet. I went into the basement (unfinished) and I followed the hot water along the copper pipes from the tank and I reached a point where one side of a "copper tee" the pipe is hot but the other side of the tee the water is cold. What's up with that? I only installed the shower body and have not installed the cartridge which I was planning to install after the ceramic installed. I am stuck and I really do not want to slap on my ceramic until I get this resolved.

Thx all in advance

Just want to add new info. It would seem that hot water in the whole house is not working unless the newly installed faucet is running.

You need to install the cartridge. With out the cartridge the hot & cold are mixing through the valve body.

John

Thx John.

Just so I understand. The hot and cold are mixing in the valve body and then bleeding back into the hot supply line when I turn another faucet on?

Yes. With no flow, pressure in the cold line is slightly higher than in the hot, due to losses such as through the tank, etc. This is enough to cause flow of cold back down the cold line. When you run some water, hot comes back up the line.

The Delta R10000 valve is famous for this, since it comes with cartridge not installed, and an oh-so-convenient blank plug, so folks put it in and leave it while they work on the tile or whatever. What you missed is that it also comes with an internal plug, to be installed to prevent water flow. You may have lost that or forgot to put it in.

Thx John and Jimbo

I inserted the cartridge and the problem is resolved. The whole idea of the blank plug for us DIY'ers makes sense since I am sure I will get mud on the cartridge and bang it around a few times before the project is over. I just wish they would have cautioned us against this in the instructions.........but then again we wouldn't need this forum.

Thx again.

valve

Tape a baggie over the valve during construction.