Specifications

INSTALLATION – SOLAR STORAGE TANK
28
CIRCULATED HOT WATER FLOW AND RETURN SYSTEM
The solar storage tank of a solar 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 and energy gained
from the sun lost through the pipe work.
If a circulated flow and return system is required, it is necessary to connect the return line after the solar
storage tank and prior to the in-series water heater supplied from the solar water heater.
If the in-series gas booster is mounted on the solar storage tank, then a suitable Tee must be installed at the
inlet to the gas booster, after the flexible hose from the solar hot outlet on the tank. The circulated return line
is to be connected to the Tee.
A Rheem 871 or 874 model in-series gas booster can be installed as part of a circulated hot water flow and
return system in a building.
If the in-series water heater is a continuous flow water heater, its preset outlet temperature setting must be
set to at least either 60°C, or to at least 70°C to meet the requirement of AS 3498, or at least 70°C if the
water temperature decreases by more than 5°C through a circulated hot water flow and return system due to
heat loss in the ring main.
If the in-series water heater is a storage water heater, its thermostat must always be set to at least 60°C.
Notes:
Water should not be circulated from a water heater with a temperature setting of less than 60°C.
If the in-series booster is a continuous flow water heater, then the circulator must be:
sized and set to provide a minimum flow rate of 3.0 L/min through the recirculated hot water flow and
return system, and
either thermostatically and / or timer controlled.
The circulator must not be set to operate continuously, i.e. 24 hours per day.
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 water heater, depending on the location of the
return line connection on the water supply line to the water heater, then either:
water will be supplied to the cold water inlet of the temperature limiting device at a temperature
exceeding the maximum recommended water supply temperature, or
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.
These conditions 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 either condition, the operation and performance of the
device cannot be guaranteed.