Interior piping does not require protection against water and UV radiation damage.
However, some jacketing is usually applied to keep insulation in place, protect it
from physical damage and improve its appearance.
Bypass and Balancing Valves
The configuration of flow balancing and bypass valves should be compared against
the system's operation and maintenance manual. Some systems have tags or
labels at each valve handle to indicate the appropriate position for various
If neither source of information exists, it will be necessary to trace the piping to
check valve positions. Use pumps and check valves for clues to flow directions.
Note missing tags on Inspection Worksheet.
Whenever possible, check for proper tempering valve operation. This can only be
done when the outlet temperature of the tank preceding the valve is hotter than the
To check, run hot water from a fixture until the temperature stabilizes and measure
the temperature. Tempering valves are normally used only on DHW systems, and
the water temperature at the fixture should be within five degrees of 120F.
Pressure Relief Valves
Pressure relief valves must be used on the collector loops of closed-loop solar
systems. Look for evidence of leakage or blowoff, and properly installed discharge
piping. Large systems may discharge into a bucket or drum, to save the solar fluid
A pressure-only relief valve must not be used on tanks or any
other pressurized city water piping. A combination temperature
and pressure relief valve must be used for these applications.
3.1 INSPECTION PROCEDURES