Criterion 6.1.5.6 Temperature Control

Criterion text:
The system shall be equipped with a means for automatically limiting the temperature of the hot water at the fixtures to a selectable temperature. The range of selectability shall be at least 10 degrees C (18 degrees F) and shall include a set point of 50 degrees C (122 degrees F).

Comments:
The use of a mixing or anti-scald valve will be used to meet the requirements of this standard.

Use the valve that has been specified by the manufacturer for the approved SRCC system that is being installed.

Although the installer will be required to install the specific valve that has been approved for this system, the installer should also understand the difference between a common tempering valve and a true anti-scald valve.

A tempering valve is meant to be used as a "BTU conserver", while a true anti-scald valve is recognized as a "safety" valve. Manufacturers and installers must understand the difference between these two valves, especially as they relate to safety and legal ramifications.

Figure 1 illustrates a standard "tempering" valve that is meant to be used as a "hot water extender" and not as a "safety" device.

Figure 1

The manufacturer, as indicated in Figure 2, has made sure to point out that these tempering valves are not to be used to provide anti-scald service.

Figure 2

Installers must also understand that the installation requirements of the tempering and anti-scald valves very often differ. In most cases, tempering valves must be installed with a heat trap while the anti-scald valves do not require this additional plumbing.

A very common anti-scald valve used in the solar industry is shown in Figures 3 and 4. Note that the valve does not require a heat trap and thus can be installed directly to the hot out port. In addition, note in Figure 3 that the valve can be set to various temperature levels.

Figure 3

Figure 4

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