Plumbing issue with an outdoor shower

This weekend I plumbed an outdoor shower that will be drained seasonally. I ran 1/2 inch pex out to the shower area and built a shower 'manifold' out of copper.

The manifold - the hot and cold lines run up seperatley to simple gate valves. After the lines pass through the gate valves they run to a copper t and then up to the shower head.

I tested the hot and was pleased with no leaks and ok water preassure. I then connected the cold and tested the shower. To my surprise, there was no water preassure at the shower head. The hot water ran up the cold water line when both valves were open.

Is there a preassure balancer or a water backflow preventer that I can install to prevent this? Or will a standard mixing valve that comes along with a shower assembly prevent the higher preassure hot moving up the cold water line?

I wanted to stay away from the single dial shower assembly and use a simpler outdoor friendly hot and cold spigot.

Thanks,

Typically, the hot pressure is just slightly lower than the cold, so if anything you would have cold water back-filling the hot pipe. But the path of least resistance by far is the shower head, so no matter what is going on temp. wise, you should get water out of the head. It sound like the head has become blocked by some debris which got into the line.


You may not be happy with the performance of gate valves. They will probably tend to drip, and are not really the proper type of valve for throttling, They are meant to be full open or full closed.

Did you try your cold water line with the hot off? What you describe sounds like what would happen if the cold is connected to an outside faucet that is open outside, but with the line shut off inside.

I don't think the line is clogged. It seems that the path of least resistance would be the shower head - but the hot water is flowing up the cold line. Both the hot and cold were turned on.

I need to check the situation with the cold on and hot off. I'll do that this eve.

Would a standard mixing valve on shower assembly correct this if it is a balance issue or would I need to somehow increase the water flow on the cold?
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Some history - the PEX tube connects to a 1/2 inch copper. The 1/2 copper conntects to a 3/4 inch branch line. The system runs like this...

1/2 copper with gate valve to 1/2 PEX. PEX T connects to a ball valve for draining the system. The other end of the T runs the PEX line to the outdoor shower. The PEX tube run is ~ 90 feet. The cold run has a T on the end. One side of the T goes to the shower. The other side will connect to a hose outlet (currently stubbed off and closed with a PEX end cap). The hot run just connects to the shower. The system will be drained in the fall and left open for winter.

The only way the hot water will run "up the cold water line" is if there is some outlet for the cold water. I still suspect an open outdoor faucet.

flow

If no water comes out of the shower head, you either made a bad mistake while piping it, or the shower head is plugged. There is no other possibility. Once that is solved, then there may always be some crossover, if there is a pressure imbalance and the shower head cannot deliver all the water coming out of the gate valves. A regular shower, or any faucet, valve has very small openings in the seats so that the flow is regulated to the amount of water needed, not all that could be delivered. Your gate valves can "deliver" much more water than the shower head is rated for, and any excess can backflow to the other side during a pressure imbalance situation. Your "shower unit" is poorly designed.

I live in ca

and installed a nice outdoor shower near our hot tub. may I ask why you didn't just buy a shower valve?

Thanks for the advice... no need to tell me that it's poorly designed - I knew that on Sunday when I thought about taking an outdoor shower...

As for the question why I didn't just buy a shower valve... Did my wife call you and ask you to post that?

Not sure why I didn't... I guess I thought it would be cool to build one. I will be heading to the box store for a shower valve this week. Hopefully taking a nice garden shower sometime this weekend.

If not, I have ~90 feet of red and white PEX that's slightly used any takers?