Rheem 871 Series Owner's Manual And Installation Instructions page 49

Where a temperature limiting device is installed adjacent to the in-series gas booster, the cold water line to
the temperature limiting device can be branched off the cold water line either before or after the isolation
valve and pressure limiting valve to the solar storage tank, but it MUST BE before the non return valve prior
to an open circuit direct system. The cold water line to the temperature limiting device can be branched off
the cold water line either before or after the non return valve prior to a closed circuit indirect system. If an
expansion control valve is required, it must always be installed after the non return valve and be the last
valve prior to the solar storage tank.
Warning: A non return valve MUST BE installed on the cold water line to the solar storage tank AFTER
the cold water branch to a temperature limiting device prior to an open circuit direct system. Due to the
higher water temperatures generated under certain conditions in the solar collectors of an open circuit direct
solar water heater, an additional effective back-flow prevention device also should be used as an extra
safeguard. Valve manufacturer RMC recommends Dual Check Valve model N7150, as being suitable for this
application.
If a combination isolation valve and non return valve (duo or trio valve) is installed on the cold water line to
an open circuit direct solar water heater and the cold water line to the temperature limiting device branches
off after this valve, then a second non return valve must be installed between the cold water branch and the
solar storage tank. Due to the higher water temperatures generated under certain conditions in the solar
collectors of an open circuit direct pumped solar water heater, an effective back-flow prevention device
should be used as the second non return valve as an extra safeguard. Valve manufacturer RMC
recommends Dual Check Valve model N7150, as being suitable for this application.
If a pressure limiting valve is installed on the cold water line to the solar water heater and the cold water line
to a temperature limiting device branches off before this valve or from another cold water line in the
premises, then a pressure limiting valve of an equal pressure setting may be required prior to the
temperature limiting device.
In-series Gas Booster as part of an Open Circuit Direct Solar Water Heater Installation
In-series Gas Booster as part of a Closed Circuit Indirect Solar Water Heater Installation
Two Temperature Zones Using a Temperature Limiting Device
Two Temperature Zones Using a Temperature Limiting Device
INSTALLATION – WATER HEATER
49
from solar
storage tank
to solar
storage tank
from solar
storage tank
to solar
storage tank