open issue - Plumbing Engineer

Code Classroom
Ron George, CPD
President, Plumb-Tech Design & Consulting Services, LLC
Warning! Anti-scald shower valves can scald you!
(Part 2)
Editor’s Note: The following is a continuation of last
month’s column from Ron George.
Every year, thousands of people suffer serious thermal
shock and/or scalding injuries in showers or
combination tub/shower fixtures. Tens of millions
of currently installed code compliant shower valves,
referred to as anti-scald or safety shower valves, can
potentially scald people.
Plumbing inspector’s responsibility
I recently spoke to a group of about 80 at a code
inspectors’ conference. I asked by a show of hands how
many inspectors carried a temperature gauge or thermometer
with them on a final inspection to check for the
maximum temperature at a shower or tub/shower. Only
a couple raised their hands. When I asked why, one person
said that his municipality would not pay for expensive
testing equipment. I explained that you can a food
thermometer (available at the grocery store for about ten
bucks) can be used. Another said he never thought to use
a thermometer and that he tested the water temperature
by feeling it; as long as it did not get too hot, he considered
it all right. Most attendees said they had not given
the problem much thought. Several said they were going
to purchase thermometers.
Model Plumbing Code requirements for showers
The two model plumbing codes in the United States
have the following language covering showers:
The 2009 International Plumbing Code
424.3 Individual shower valves.
Individual shower and tub-shower combination valves
shall be balanced-pressure, thermostatic or combination
balanced-pressure/thermostatic valves that conform
to the requirements of ASSE 1016 or ASME
A112.18.1/CSA B125.1 and shall be installed at the
point of use. Shower and tub-shower combination valves
required by this section shall be equipped with a means
to limit the maximum setting of the valve to 120°F
(49°C), which shall be field adjusted in accordance with
the manufacturer's instructions. In-line thermostatic
valves shall not be utilized for compliance with this section.
The 2009 Uniform Plumbing Code
418.0 Shower and Tub-Shower Combination
Control Valves.
Showers and tub-shower combinations in buildings
shall be provided with individual control valves of the
pressure balance, thermostatic, or combination pressure
balance/thermostatic mixing valve type that provide
scald and thermal shock protection. These valves shall
conform to ASSE 1016 or ASME A112.18.1/CSA B125.1.
Gang showers, when supplied with a single temperature-controlled
water supply pipe, shall be controlled by
a mixing valve that conforms to ASSE 1069. Handle
position stops shall be provided on such valves and
shall be adjusted per the manufacturer’s instructions to
deliver a maximum mixed water setting of 120°F
(49°C). The water heater thermostat shall not be considered
a suitable control for meeting this provision
Limit stop readjustment needed.
The maximum temperature limit stop on all pressurebalancing
type shower valves should be readjusted seasonally
to correct for changes in the incoming cold
water temperatures. These temperatures can vary as
much as 50 degrees in some areas, which can correspond
to a relative change in the outlet temperature,
based on the delivered hot water temperature and the
ratio of hot to cold. I recommend having maintenance
workers check the limit stops at least twice a year to
assure the maximum hot water temperature does not
exceed 120 F.
All compensating type shower valves should be readjusted
every time there is a change in the domestic hot
water system that could affect the system temperature.
The limit stop should be readjusted when a water heater
is replaced, when the master thermostatic mixing valve
temperature is readjusted, when the circulating pump is
replaced, when the thermostat on the water heater is
adjusted or if any work is done on the hot water system
that can potentially change the hot water delivery temperature.
Manufacturers of all hot water system components
should mention this in their literature.
Schools and institutional facilities
For gang showers in schools or prisons, where the
bather cannot adjust the temperature, there is typically
an on-off shower valve or a metering button. Shower
valves for this application are set by staff, and the thermostatic
mixing valve should comply with the standard
titled ASSE 1069-2005 - Performance Requirements for
Automatic Temperature Control Mixing Valves for gang
showers. In all cases water should be flowed from the
shower valve long enough to assure that the water temperature
is not a hazard. n
Ron George is president of Plumb-Tech Design and
Consulting Services LLC. He has served as chairman of
the International Residential Plumbing & Mechanical
Code Committee. Visit www.Plumb-TechLLC.com, email
Ron@Plumb-TechLLC.com or phone 734/755-1908.
The views and opinions expressed in this column are those of the author and
do not reflect those of Plumbing Engineer, TMB Publishing, or ASPE.
Page 30/Plumbing Engineer April 2012