View Full Version : Preventing "Shower shock"

06-18-2011, 12:05 PM
I just purchased a home that does not have anti-scalding prevention in the shower stall or bath tub. The shower is a two-valve system (hot and cold) and the tub is three valve (hot, cold, diverter). Both of these have ceramic tile on the walls and there is no easy access to get behind the fixtures (the bath tub fixtures are on an external wall). I was wondering if I can install remote pressure valves in the basement for each set of hot and cold lines going to each location to prevent scalding. If this sounds like a reasonable solution, can you recommend a good remote valve?


06-18-2011, 12:15 PM
If it is only the shower you are concerned with, you could replace the shower heads with anti-scald versions. They also make anti-scald tub spouts.

I've read about retrofit tempering valves to reduce the temperature of the hot water but don't know if they are pressure balanced or just temperature sensing.


06-18-2011, 12:21 PM
You can cut the tile, and use a repair plate.

Or Grohe makes a balancing valve that goes on the incoming pipes to the shower valve.


06-18-2011, 12:33 PM
There are two different scalding risks. A pressure balance system can still scald if only the hot water tap is turned on and the temperature in the tank is high enough. There exist also, tempering systems that blend some cold in with the hot to reduce how hot the water from the hot tap can be. A tempering system at the hot water tank can reduce the risk of scalding from all outlets but can affect how well a dishwasher works.

06-18-2011, 06:08 PM
The ONLY thing that can prevent "thermal shock" is a balancing valve. IF you use a "remote" one it has to be installed in the hot and cold lines TO THE TUB or SHOWER, not in the piping to the bathroom. For one thing the internal ports are so small that THEY would cause the thermal shock if anyone used hot or cold water in the bathroom while the tub or shower was being used.

06-18-2011, 06:36 PM
All modern shower valves, at least the pressure balance types, have a means of limiting how hot you can make the output. They do this by putting a cam, screw, or some other method of restricting the movement of the handle. Now, I'm sure there are many that were never adjusted per the manufacturer's instructions and aren't doing their jobs, but they are on all newer valves designed for a shower. Generally, it isn't as big a deal on a tub, and it's possible, if it is a tub only valve, it may not have this (but almost all valves are designed for either/both functions thus have it).