Hot Water Fluctuations In The Shower
by Pete Busch

If you have an older home you may have noticed that when your taking a shower the water temperature will fluctuate, sometimes a lot. When a toilet is flushed the pressure is reduced on the cold water supply pipes. This will reduce the amount of cold water going to your shower resulting in very hot water spraying all over you. The same holds true if someone turns on the hot water somewhere else in the home. Your shower water will get cold, you adjust to warm it back up, they turn the hot water off and now your shower is blasting out really hot water, not good.

Unwanted temperature fluctuations are more than just an annoyance. Hot water scalds account for 20% of all burns, more than 2000 children are scalded each year in the US. Water that is 160 degrees can cause scalding in just .5 seconds.

If you are experiencing this situation you may want to consider having a plumber install a device known as an anti-scald valve, also known as tempering valve or mixing valve. These valves will automatically balance the water temperature. They look similar to ordinary shower and tub valves and are equipped with a special diaphragm or piston mechanism that immediately balances the pressure of the hot- and cold-water inputs, limiting one or the other to keep the temperature within a range of several degrees. Some faucets have this built in so if you are not experiencing this problem then your good to go.

Its been my experience as a St. Paul, Minnesota home inspector that many homes, especially older homes, do not have these devices installed.

Pete Busch
St Paul, Minnesota Home Inspector
763 442 4039