San Diego Union-Tribune (Sunday)
Ensure a perfect-temperature shower or bath
Thermostatic mixing valve offers comfort and scald protection
There are few things more aggravating or uncomfortable in life than taking a shower and suddenly feeling a burst of extremely hot or cold water after a cohabitant flushes the toilet or turns on the sink. This phenomenon happens more often than you’d think in many homes. And in worst-case scenarios it can result in dangerous skin burns or, at least, friction among family members.
The solution? Consider installing a thermostatic mixing valve (TMV) in your bathroom shower.
Joe Wood, a plumber and founder of Boston Standard Company in Boston, explained that a TMV is a special plumbing component that mixes the incoming hot and cold water to ensure safe temperature for the use of the shower or bath.
“This fixture not only protects the user from surges of hot and cold water if there are irregular pressures in the building — such as when you flush the toilet — it also allows you to limit the total temperature of hot water coming out of the fixture, which is useful for homes with elderly or young children who are more susceptible to scalding,” he said.
The most notable benefit of a TMV is that you can set the desired water temperature value using a dial, knob, or other control that works with the valve. Consequently, when you turn on the shower or bath, the water temperature will automatically adjust to your preset temperature preference and consistently remain there as you bathe or shower (unless, of course, you run out of hot water because you’ve taken too long of a shower or bath).
“You have the confidence that your water temperature will remain constant, regardless of pressure variations. Along with providing maximum comfor t, a thermostatic mixer valve also saves water and energy,” said Tanya Klien with Anta Plumbing in Toronto. “You don’t have to worry about fiddling with your shower handle to find the ideal temperature.”
Unlike a pressure-balanced shower valve, which can accomplish the same goals, a thermostatic mixing valve can also achieve a higher flow rate, mean
ing you won’t have to compromise water pressure while taking a shower.
But this plumbing upgrade comes with trade-offs.
“Scale can build up within the valve components over years of consecutive use, which may require eventual repairs and system flushing,” cautioned Jordan Collins, a home maintenance expert at Uk-based Two Lions 11 Ltd.
Additionally, installation may require you to retrofit your tub or shower, which could involve opening the wall to conceal the plumbing behind it, according to Wood.
“The main disadvantage is that it can be relatively expensive in terms of parts and installation,” Klien said, who strongly recommends hiring an experienced plumbing professional for the job. “This valve can be retrofitted into existing plumbing, but it will likely require severing, reconnecting, and soldiering necessar y plumbing joints so that ceiling gaskets don’t melt or warp.”
Often, the mixing valve roughin hardware or kit can be less expensive than the trim piece that includes the shower/tub controls – especially if you opt for a higher-end finish like brushed nickel.
“Anticipate paying anywhere from $300 to $800 or more for materials and labor,” Collins said. “That price can rise if your plumbing presents special challenges.”
Before choosing a TMV product, make sure it follows NSF international standards and includes a warranty.
“You also want to ensure that the deliver y of water to be used for bathing and washing is controlled by valves listed to ASSE standard 1016 Type T or ASSE standard 1070 for both scald and thermal shock protection,” Klien recommended.
For best results, hire a pro to inspect your bathroom set up and plumbing before purchasing any TMV products.
“An inspection from an expert can generate helpful suggestions based on your home’s characteristics,” Collins noted.