Anti-Scald Devices Keep Shower Temperature Under Control

You’re happily swabbing yourself down in the shower. Suddenly someone flushes a toilet, the water grows hotter than a Habanero chili and you’re howling for mercy and swiping at the shower control from a safe corner.

Aside from strengthening your vocabulary and your reaction time, such incidents serve mainly as a temporary irritant. But, according to experts, several thousand people each year suffer severe scalds and thermal shock injuries caused by instantaneous water temperature changes while they are bathing.

While exact numbers are hard to come by, the National Safe Kids Campaign, a program headed by former U.S. Surgeon General C. Everett Koop, estimates that 5,000 children are scalded in the bathtub each year. In general, “hot water burns are the single most common way for a child to be burned,” says Dr. Bruce Achauer, director of the UCI Burn Center and chairman of the Burn Prevention Committee of the American Burn Assn.

The elderly and the physically challenged also suffer a disproportionate number of injuries when bath water temperatures fluctuate.

And, when there’s a sudden change in water temperature, the individual reacts instinctively to escape the water. Such shock reactions lead to slipping and knocking body parts against the shower, resulting in further injuries.

Such unnecessary injuries should tail away in the next five to 10 years. Anti-scald valves are making their way into the residential plumbing codes across the country.

“The codes have been passed at the level affecting single-family new construction and will be put into effect in the next 12 months,” says Reed Fry, director of marketing for the Rohl Corp. in Costa Mesa. Rohl is the importing arm for KWC bathroom and kitchen faucets; its KWCdomo line protects against scalds and maintains constant temperatures despite water supply fluctuations.

Within two years, the anti-scald valves will also heavily impact the remodeling market as municipal codes incorporate anti-scald requirements, Fry says.

The simplest way to cut the risk of scalding in the shower is to set your water heater to a temperature of 120 degrees or lower. A 140-degree setting, not at all uncommon, can produce a water flow that will severely burn a child in three seconds or an adult in five seconds.

People usually bathe in water between 96 and 102 degrees, notes Joel Kleinberg, a Los Angeles attorney and board member of the American Scald Burn Foundation who has handled liability cases resulting from scalding.

Curiously, only in the last decade has there been a concerted effort to push such anti-scald codes for single-family residences, although they have been widely mandated in commercial codes. “It should be old news,” Kleinberg says.

The anti-scald valve means greater safety because it limits opportunities for both scalding and thermal shock.

The anti-scald valve has been around for 50 years or more, but for a variety of reasons it never caught on in residential construction. They are more expensive ($20 to $25) than the low-end residential two-handle lines and plumbing codes did not require them.

Manufacturers of two-handle faucets did not have the technology to produce anti-scald valves, so they opposed such codes. Contractors did not spend much time telling buyers what options were available behind the shower face plate. And for plumbers, the valves meant extra work with unfamiliar items.

Thus, the anti-scald valve rested in near oblivion.

But consumers are becoming more aware of this feature from a comfort and a safety standpoint, says John Schott, senior product manager for faucets--including the Rite-Temp line of anti-scald valves--at the Kohler Co. in Kohler, Wis.

Anti-scald valves of all types now account for only 20% to 25% of the total market, estimates John Diohep, vice president of sales for Symmons Industries in Braintree, Mass. More than 30 years ago, Symmons was the first company to market a fully pressure-balanced anti-scald valve.

There are two schools of thought on anti-scald valve design. These single-handle valves use pressure and/or temperature balancing techniques to quell large temperature changes even as they get started. While code requirements vary, most establish that the valve keeps the temperature within three degrees plus or minus of the original setting, to prevent thermal shock reactions.

Pressure-balanced valves respond to pressure disturbances in the lines, Diohep explains. A stainless steel piston slides toward the higher pressure, reducing hot water flow if the cold water flow drops, and vice versa.

Thermostatic valves have bimetallic valves that expand as the temperature increases, reducing the hot water flow. The more expensive combination thermostatic/pressure-balanced valves, such as those made by Leonard Valve, control both temperature and pressure, adjusting for the pressure indirectly. Such a combination provides an extra level of protection, says Greg Wilcox, vice president at Leonard Valve in Cranston, R.I.

The pressure-balanced valves reportedly respond more quickly to temperature changes, reacting in less than a second to a pressure change. The thermostatic valves respond to a temperature change in one to two seconds. However, the pressure-balanced valves require the temperature limit be set by the plumber on site. The limits on the thermostatic valves can be preset.

The anti-scald valves of both types have adjustable limit stops that prevent incoming water from exceeding a set temperature. Some units have an override button that can be pushed to get hotter water, but most limit stops use a screw adjustment.