Criterion 6.1.1.2 Solar Loop Isolation

Criterion text:
Isolation/bypass valves must be installed to allow the system owner to bypass the solar storage tank in the case of a two-tank system, or to shut off the cold water supply to the solar tank in a one-tank system. All isolation valves shall be labeled with their normal operating position indicated.

Comments:
The installer must install all isolation valves included in the SRCC approved solar system. The manufacturer's system schematic as well as the SRCC system schematic indicate the required valves and their locations.

In addition, the installer must include a label or tag with each isolation valve. The label or tag will identify the valves' normal operating position. The tags and labels are to be provided by the manufacturer.

Note that the isolation valves in Figure 1 have been tagged. The tags provide information on the function of the valves as well as indicate their normal operating position. Identifying the normal operating position is especially critical for the homeowner in the event the valve handle has been readjusted for one reason or another. In addition, these tag provides valuable (and readily available) information for future service personnel.

Figure 1

In many installations, a large number of isolation valves are used. This can at times be quite confusing for the system owner and service personnel. Identifying the function of the isolation valves in Figure 2 can be quite frustrating. (Compare the situation in Figure 2 with that in Figure 3 where the valves are labeled and identified.) Labels and tags serve to easily identify the valves and their function in the overall design of the system.

Figure 2

The use of accompanying tags and labels (Figures 3 and 4) in a multi-valve system greatly simplifies the understanding of not only the valves, but overall system design and operation.

Figure 3

Figure 4

Figure 5 shows that this installer includes tags on a variety of other valves for quick identification. Note that the system manual is also exhibited in a prominent location for future reference.

Figure 5

The valve tag shown in Figure 6 states "Valve used to by-pass solar heater" but does not indicate the normal operating position of the valve. Of course, those familiar with ball type isolation valves understand the relationship between the handle orientation and the valves operation, but homeowners may not be as adept at determining this. Instruction as to the position of the valve handle for normal operation should be included.

Figure 6

The most common isolation valves used are the ball type valves (Figure 7) due to their ease of use and reliability. In the past, gate valves (Figure 8) had been used for isolation purposes, but this is no longer the case. Gate valves were primarily used as cold service water isolation valves. The use of gate valves as isolation valves in solar systems is not recommended.

Figure 7

Figure 8

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