Safety is a main focus of this edition of Working Pressure. One category of safety equipment used in plumbing systems are those products that control temperature. ASSE has a portfolio of standards related to temperature control devices and their applications. I thought that I would provide a brief summary of these standards and the use of the devices in the field.
The standard that covers the fitting for which most are familiar is ASSE 1016/ASME A112.1016/CSA B125.16, Automatic Compensating Valves for Individual Showers and Tub/Shower Combinations. As you can tell from the designator, this standard is harmonized between three standards development organizations — the others being ASME and CSA. These valves are the single handle shower valves that we are accustomed to. They mix the hot and cold water to distribute tepid water to the bather. Hence, the devices are known as “mixing valves.”
ASSE 1016 devices provide anti-scald protection, as well as limit the maximum temperature and prevent thermal shock. Thermal shock is the phenomenon where there is a sudden and noticeable change in the discharge water temperature. It is often proceeded by a significate change in water demand, such as the flushing of a toilet.
The next devices to discuss are covered by ASSE 1017, Temperature Actuated Mixing Valves for Hot Water Distribution Systems. These are often referred to “Master Mixing Valves.” These devices control the in-line water temperature and are installed at the hot water source. These valves do not protect against scalding — they are for temperature control only. Devices that comply with ASSE 1017 are often listed to ASSE 1070 as well (the reverse is not true).
Closely related to ASSE 1017 devices are ASSE 1070/ASME A112.1070/CSA B125.70, Water Temperature Limiting Devices. Again, this is a harmonized standard. ASSE 1070 devices are used to limit the tempered water to fittings that discharge in fixtures such as lavatories, bidets, and bathtubs. These devices do not address thermal shock.
The next standard is ASSE 1066, Performance Requirements for Individual Pressure Balancing In-Line Valves for Individual Fixture Fittings. An ASSE 1066 device equalizes incoming hot and cold water line pressures for the purpose of minimizing mixed water temperature variations. These are used in conjunction with two handle valve sets. They are not designed to limit the maximum outlet temperature at the point-of-use.
ASSE 1069, Performance Requirements for Automatic Temperature Control Mixing Valves, covers devices that control the water temperature to individual or multiple fixtures to reduce the risk of scalding and thermal shock. These devices are installed where the bather has no access to the temperature adjustment means, and where no further mixing occurs downstream of the device.
The last of the mechanical device standards — ASSE 1071, Performance Requirements for Temperature Actuated Mixing Valves for Plumbed Emergency Equipment — is for a very specific application. As the name states, these are used with plumbed emergency showers and eyewash stations. These mixing valves contain a temperature controlling element that is set to a specific outlet temperature. Their purpose is to limit the maximum outlet temperature.
As the use of electronic controls become more prevalent in water heaters, the ability to control temperatures with precision and accuracy has improved. This has resulted in a class of water heater that can control temperature, similar to the mechanical devices just described. As a result, new standards have been developed to include these products.
ASSE 1082, Performance Requirements for Water Heaters with Integral Temperature Control Devices for Hot Water Distribution Systems, is similar to ASSE 1017. The controls on these heaters are similar in that they control the inline water temperature and are installed at the hot water source. However, these valves do not protect against scalding. They are for temperature control to specific temperature limits. These devices are not for point of use application.
ASSE 1084, Performance Requirements for Water Heaters with Temperature Limiting Capacity, covers heaters with control that perform the same function as an ASSE 1070 device. These devices heat and control temperature to a maximum of 120°F and connect to downstream fixture fittings.
And finally, ASSE 1085, Performance Requirements for Water Heaters for Emergency Equipment, provides temperature control similar to an ASSE 1071 device. These water heaters heat the cold water supply to an acceptable tepid temperature for emergency equipment.
As you will notice, there are many different standards covering temperature control devices. This is a lot of information, but the takeaway should be that specific application requires very specific devices. The requirements can be found in the standards unique to the device in use.
