Specifications

INSTALLATION – WATER HEATER
30
Gas Booster for a Solar Water Heater
The temperature limiting device used with a CG20-60 model in-series gas booster as part of a solar water
heater installation must have the additional capability of receiving a hot water supply temperature of up to
99°C if the solar water heater does not have an over temperature protection system to limit the water to no
greater than 90°C.
Warning: Temperature controllers must not be fitted to this water heater (CG20-60 model) if it is
installed as an in-series gas booster with a solar water heater because water at a temperature much higher
than the controller setting can be delivered. If a solar water heater is installed to an existing water heater
installation, then all controllers must be disconnected and removed.
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. 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.
LEGEND
In-series Gas Booster as part of a Direct Solar Water Heater Installation
Two Temperature Zones Using a Temperature Limiting Device
from solar
storage tank
to solar
storage tank