Written by IAPMO 3:32 pm ASSE, IAPMO News

Still Confused About Water Temperature Control Devices?

A little over five years ago, an article titled “When Will the Confusion End?” was published in ASSE’s former publication, Backflow Prevention & Plumbing Standards (BPPS) magazine. That April 2016 article hoped to explain which water temperature control devices should be installed for particular applications and why. Feedback, at that time, agreed that it helped, but more information was needed.

Since then, ASSE’s Scald Awareness Task Group published a white paper titled, “Guidelines for Temperature Control Devices in Domestic Hot Water Systems,” along with a corresponding “pocket guide,” which outlines the proper water temperature control device to be used in various applications. Additionally, ASSE International published three new product performance standards for water heaters that precisely control their outlet temperature. All of these tools can help you make your temperature control device selection more easily.

Here’s the entire list of ASSE’s product performance standards for water temperature control:

ASSE 1016-2017/ASME A112.1016-2017/CSA B125.16.17
Automatic Compensating Valves for Individual Showers and Tub/Shower Combinations

These devices are to be used, as the title states, for individual showers and tub/shower combinations ONLY. This type of device provides both scald and thermal shock protection installed at the point of use and is the final temperature control with no further mixing allowed. We should all know by now that three types of valves meet the 1016 standard:

  • Type “P” devices sense the cold and hot water supply pressures and adjust for any variations in these pressures to maintain the outlet water temperature.
  • Type “T” devices sense the water temperature at the outlet and adjust the incoming cold and hot water to maintain the outlet water temperature.
  • Type “T/P” devices sense the cold and hot water supply pressures and outlet water temperature, and adjust both the pressure and temperature variations to maintain the outlet water temperature.

ASSE 1017-2009
Temperature Actuated Mixing Valves for Hot Water Distribution Systems

These devices are to be used to control the temperature of the hot water distribution system and to be installed at or near the hot water source. These devices are for hot water distribution systems ONLY. Since this type of device does not provide scald or thermal shock protection, additional downstream temperature control devices are required. A working group is currently looking at possible revisions to this standard.

ASSE 1062-2017
Temperature Actuated, Flow Reduction (TAFR) Valves for Individual Fixture Fittings

These devices can be integral or added on to fixture fittings such as showerheads, bathtub/whirlpool tub spouts, and some sink fittings. They are designed to reduce the flow to a trickle (0.25 gpm or less) within 5 seconds in response to a temperature greater than a preset outlet temperature. These devices ONLY provide scald protection.

ASSE 1066-2020
Individual Pressure Balancing In-Line Valves for Individual Fixture Fittings

These devices are used to equalize incoming hot and cold water pressures in order to minimize the outlet temperature variations when used with a mixing valve or two handle valve set. They DO NOT provide scald protection but DO provide thermal shock protection.

ASSE 1069-2020
Automatic Temperature Control Mixing Valves

These devices supply tempered water ONLY at a preset temperature to SINGLE pipe gang (group) showers and sitz baths. They provide BOTH scald and thermal shock protection. The end user has no control of the final temperature.

ASSE 1070-2020/ASME A112.1070-2020/CSA B125.70:20
Water Temperature Limiting Devices

These devices limit the hot or tempered water temperature to fixture fittings such as sinks, bathtubs, bidets, and lavatories to reduce the risk of scalding. Mixing with cold water at the point of use is intended. They ONLY provide scald protection.

ASSE 1071-2012(R2021)
Temperature Actuate Mixing Valves for Plumbed Emergency Equipment

These devices are intended to be a component of eyewash, eye/face wash, drench showers, and combination units to provide tempered water in compliance with ANSI Z358.1. These devices ONLY provide scald protection.

ASSE 1082-2018
Water Heaters with Integral Temperature Control Devices for Hot Water Distribution Systems

Water heaters, both tank type and tankless, listed to this standard control the outlet temperature to the hot water distribution SYSTEM at a defined setpoint under various steady-state flow conditions. The limits of this setpoint are very similar to those of ASSE 1017. This type of water heater does NOT provide scald or thermal shock protection. Additional temperature control devices are needed downstream at the point of use. Essentially, this type of water heater has a similar built-in means to control the outlet water temperature to the distribution system as adding a 1017 device to a tank type or tankless water heater.

ASSE 1084-2018
Water Heaters with Temperature Limiting Capacity

Water heaters listed to this standard precisely control the outlet temperature under varying flow conditions to provide tempered water at the point of use. Mixing with cold water at the point of use is intended. These water heaters provide a level of scald protection consistent with ASSE 1070 devices. They are NOT intended to be a substitute for an ASSE 1016 device. This type of water heater is essentially a point of use water heater that controls the outlet temperature, similar to adding a 1070 valve to the system at the point of use.

ASSE 1085-2018
Water Heaters for Emergency Equipment

Water heaters listed to this standard control the outlet water temperature to a precise setpoint at varying flow conditions to supply tepid water to emergency equipment in compliance with the range listed in ANSI Z358.1.

These 10 product standards give us the valves, faucets, fixture fittings, devices, and water heaters that can be used to help us as designers, engineers, installers, and inspectors to prevent the potential for scald injuries and slip/fall injuries due to thermal shock. So, now that we have all of this information, what is the simple and easy way to choose the correct device? The Scald Awareness Task Group put this chart together to help with that selection, but first, you must ask yourself a number of questions:

  1. Do I need scald protection, thermal shock protection, or both?
  2. Will further mixing downstream happen or be needed?
  3. Where will the device be installed? Will the end user need access?
  4. Is the device the final temperature adjustment or can the end user adjust at the point of use?
  5. Does the device control the temperature of the hot water distribution system?

Now, take your answers and plug them into the chart below to choose the correct device. Of course, you will need
to confirm your selection using the manufacturer’s literature and installation instructions. This identical chart is part of the handy “pocket guide” mentioned earlier.

Something else to consider — electronics have been part of our plumbing world for some time now and they are constantly making a larger impact on the industry. It all began with the advent of sensor-controlled faucets that deliver tempered water at a predetermined temperature; these require a 1070 type device to control that tempered water temperature.

Today, we have digitally controlled shower and tub/shower combination valves, and digital controls for hot water distribution systems, and plumbed emergency equipment.

Some of the features of digital shower valves are mind blowing:

  • Precise temperature control so the temperature is the same each time you shower
  • Preset temperature control for individual persons — some valves can be set for four people
  • Preset warm up cycle
  • Multiple temperatures for different sprays set to predetermined time cycles
  • Touch screen controls
  • Voice, Alexa, or phone control

The features of a digital system control valve:

  • Precise temperature control
  • Programmable temperature setback scheduling
  • Ability to connect to building system automation
  • Can be preset to sanitize the system to control waterborne bacteria

One of the newer features that I really enjoy is the LED temperature indicator on my showerhead. This lets me know, at a glance, the temperature of the water at the showerhead — both by looking at the color and the actual temperature displayed. My particular showerhead shows BLUE until it reaches 90 °F, changes to GREEN at 91 °F and changes to RED at 109 °F. I have my high limit stop set at 112°F. I find this feature to be very handy. Many manufacturers of showerheads and body sprays are incorporating some form of this feature into their products.

So, with all of these tools and all of this technology at our disposal, why do we still have so many scald injuries and even deaths? I know that I am preaching to the choir, as they say, but each of us in this choir of professional plumbers need to spread the message that scald injuries are preventable.

Even after choosing the correct device and installing it correctly, our job, as the installer, is not done until we instruct the owner or the owners’ representative on how to adjust the device to ensure that it continues to work as it was intended. This is particularly true with shower or tub/shower combination valves; the limit stop must be set at the time of installation — the plumbing code says so and manufacturers’ installation instructions say so. Using the excuse, “We didn’t have hot water when I installed the shower valve trim,” doesn’t cut it anymore … you need to go back after the water heater is installed and complete the installation by setting the limit stop on the shower valve. And remember, Type “P” shower valves must be checked and possibly reset seasonally, as the incoming cold water temperature changes or when the temperature setting of the water heater is either increased or decreased.

It’s hard for me to believe that the Scald Awareness Task Group was formed 12 years ago and we have completed six white papers in that time. All of the white papers, listed to the right, are available for download on ASSE’s website at www.asse-plumbing.org/asse/membership/resources.

The most important thing to take from this lengthy article is that each of us must continue to learn everyday because our industry is changing every day. Education and knowledge are the keys.


Article by Richard J. Prospal, IPP, FASSE first appeared in Working Pressure magazine


IAPMO develops and publishes the Uniform Plumbing Code®, the most widely recognized code of practice used by the plumbing industry worldwide; Uniform Mechanical Code®; Uniform Swimming Pool, Spa and Hot Tub Code®; and Uniform Solar Energy, Hydronics and Geothermal Code — the only plumbing, mechanical, solar energy and swimming pool codes designated by ANSI as American National Standards — and the Water Efficiency Standard (WE-Stand)™. IAPMO works with government, contractors, labor force, and manufacturers to produce product standards, technical manuals, personnel certification/educational programs and additional resources in order to meet the ever-evolving demands of the industry in protecting public health and safety.

Last modified: December 30, 2022