A PosiTemp faucet is a temperature-sensitive shower faucet manufactured exclusively by Moen. Most of us have experienced unexpected water temperature changes in the shower when someone runs a faucet or flushes a toilet. But because of its temperature-sensitive design, a Moen PosiTemp valve prevents children and adults from getting scalded or hit by an unexpected blast of icy-cold water while taking a shower.
How the PosiTemp Faucet Works
Behind the handle of a Moen PosiTemp tub and shower faucet are built-in stops that limit how far the handle can turn. By controlling the turning range of the handle on a Moen PosiTemp valve, these temperature limit stops restrict the water temperature range, meaning it cannot get too hot or too cold. The valve is designed to balance the incoming flow of hot or cold water, even when the pressure varies due to another faucet being turned on or a toilet flushing.
This type of valve is also called a pressure balance valve, because it balances the pressure to eliminate large changes in water pressure. A Moen PosiTemp shower valve keeps your water temperature steady within 3 degrees Fahrenheit at all times, according to Moen, but requires both hot and cold pressure to operate properly. The temperature limit stops on a Moen PosiTemp valve can also be adjusted to make the range of your handle turn longer or shorter. This will increase or decrease how hot or cold your water temperature will get.
PosiTemp Valve Trim
The valve of a Moen PosiTemp faucet looks similar to most other types of tub and shower faucets, with 1/2-inch sweat, threaded, PEX or CPVC connections for the hot and cold water, shower head and tub spout. The Moen PosiTemp trim is a bit different from that of other Moen faucets, however. The escutcheon screws that hold the trim plate to the shower valve are at the 2 o'clock and 7 o'clock position, which is unique from any other Moen trim.
This screw-hole design means that the PosiTemp trim is not interchangeable with other types of shower trim, but a PosiTemp faucet will fit any Moen PosiTemp trim. Also, while other Moen faucets have a handle or knob that pushes in and out as well as rotating left and right, the PosiTemp shower valve features a handle that only turns left and right. It points straight down when off, turns to the right to the 3 o'clock position for full cold and left to the 9 o'clock position for hot.
Moen PosiTemp Cartridge and Warranty
For many years, Moen used the slogan "Buy it for looks, buy it for life," and they back it up with a limited lifetime warranty. If something goes wrong with the PosiTemp shower valve, they will replace it by sending you a new faucet cartridge free of charge. Moen has designed the faucet to make removing and installing a cartridge very easy in case of problems.
The only problem with installing a new cartridge in a PosiTemp shower valve is that it can sometimes be installed upside down. You'll know if the cartridge is installed upside down because it can lead to problems such as very hot or scalding water when the faucet is first turned on or hot water on the cold side and cold water on the hot side. The good news is, simply removing the cartridge, turning it over and re-installing it will fix this issue.
Gary Sprague is a retired master plumber who now works as a writer. He lives with his family in Maine.