Pressure balanced shower valves

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We're building a shower from scratch. I read the tutorial about shower valves, and am still foggy.

I would like a pressure-balanced valve so that the temperature and flow remain the same when someone opens a hot tap in the kitchen. I want to control the temperature and flow to the showerhead, with a single handle control. The "expert" at an online fixture outlet tells me that the only way to do that is with an expensive thermostatically controlled valve. I could swear I've encountered single handle valves that do both.

Please let me know where I can find what I need.

Thanks, Charlie


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New England
To get constant temperature, a thermostatically controlled valve works...set it once, just use the volume control to turn it on/off.

But, for a single-handle faucet, the anti-scald functionality of the pressure balance spool valve will keep momentary flow related temperature changes from occurring. Pretty much any shower valve you buy today should have that functionality built into it, and is required for any remodel or new builds and has been since the 1980's.

What you'll see if there's a pressure/flow problem is that the anti-scald shower valve will slightly decrease the volume when someone using water elsewhere causes one supply's pressure to drop, either hot or cold. It will either add a bit more hot or cold to keep the BALANCE even, but not the pressure. When the pressure is not changing, you change the outlet temperature by moving the handle, and the pressure balance valve should keep the outlet balance between hot and cold the same. It won't compensate for running the water heater down, though, where a thermostatically controlled one will, until there's not enough hot, then it will start to cool off.
Hey, wait a minute.

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