Cozy Low-Energy Shower

Step 15 C) Temperature Stabilization: Identify the Problem

The first step is to check whether you have a problem, and if so, whether the hot is back-feeding the cold, or vice versa.

Turn on the shower, let the hot water warm up, and adjust for a moderate temperature. Now shut off the flow at the showerhead and go away for a few minutes. Come back and turn it on. If the water quickly becomes scalding hot, your hot water is back-feeding the cold water pipe. If the water is ice cold, the cold water is back-feeding the hot.

If it came out hot (hot water back-feeding the cold pipe), you need a check valve in the cold.

If it came out cold (cold water back-feeding the hot pipe), you need a check valve in the hot.

Now you need to find a location to add the valve. If the pipes are accessible near the shower, that's ideal. If not, you could add the check valve to a main hot or cold water feeding the house...but then it won't always work as well if other plumbing in the house is being used. So you may need to open up the drywall behind the shower or in the ceiling above it in order to get access to a pipe that is just feeding that shower. Once you've found the spot, measure the pipe diameter--you'll need that to choose the right fittings.

Comments

[Bruno M]

It is not allowed by the water utility company to let hot water flow back in the cold water line; so your problem ( should ) not exist. Most old fashioned showers with 2 separated valves for hot and cold have non return valves build in. But instead of breaking up walls etc, why not install a thermostatic shower valve, that mixes your water to the right temp ( and volume too)? And spills also less water while one waits for the cold water to get up to temp in your old fashioned setup?

[LowEnergy]

In buildings, at least the ones I've worked on, there are lots of things that "should not exist" that do! In my installation, I did not have to break into any walls to install the check (non-return) valve. The pipe was accessible in the basement. However, I would have had to break up the walls to install a thermostatic shower valve. So for me, what I did made sense. In buildings, every installation is different, so it won't be the same for everyone. I don't understand what you say about spilling less water. Don't you need to wait the same amount of time and dump the same water in either case?

[phb]

I think Bruno might be referring to the fact that the thermostatic shower valves actually don't release water to the showerhead itself until it's @ the set temperature. Instead, they feed the hot back to the HWS until it's up to temp. That's my understanding anyway... could well be I'm wrong! ;-)