INSTALLATION
25
CIRCULATED HOT WATER FLOW AND RETURN SYSTEM
This water heater should not be installed as part of a circulated hot water flow and return system in a building.
The benefits of solar gain will be significantly reduced.
If a circulated flow and return system is required, it is necessary to install a secondary water heater supplied
from this water heater. The flow and return lines connect to the secondary water heater, not this water heater.
The secondary water heater makes up for the pipe heat loss in the flow and return system and must be able
to provide a hot water outlet temperature of at least 60°C.
Note:
The thermostat or preset outlet temperature of the secondary water heater must always be set to
maintain a temperature of at least 60°C in the hot water flow and return line, including making up pipe heat
losses in the system.
Refer to the
Circulated Hot Water Flow and Return
– Solar PV Electric Water Heater
diagram on page 25.
Circulated Hot Water Flow and Return System
Solar PV Electric Water Heater
Temperature Limiting Device
A temperature limiting device cannot be installed in circulated hot water flow and return pipe work. The
tempered water from a temperature limiting device cannot be circulated. Where a circulated hot water flow and
return system is required in a building, a temperature limiting device can only be installed on a dead leg,
branching off the circulated hot water flow and return pipe.
If circulated tempered water were to be returned back to the secondary or in-series booster water heater, then
when the hot taps are closed no water will be supplied to the cold water inlet of the temperature limiting device
whilst hot water will continue to be supplied to the hot water inlet of the temperature limiting device.
This condition may result in either water at a temperature exceeding the requirements of AS/NZS 3500.4 being
delivered to the hot water outlets in the ablution areas, or the device closing completely and not delivering
water at all, or the device failing. Under this condition, the operation and performance of the device cannot be
guaranteed.
