No flow of water from the hot tap may indicate a restriction in or failure of the cold water supply to the water
heater. Check for water flow at other taps and that the cold water isolation valve (refer to page 25) is fully
If the water heater is installed as an in-series gas booster to a solar water heater, you may find that the water
heater operates more frequently than expected. This will occur when the solar heated water temperature is
lower than 2°C below a water heater preset outlet temperature setting of up to 75°C (i.e. below 68°C if the
preset outlet temperature setting is 70°C) or lower than 4°C below a water heater preset outlet temperature
setting of 82°C, which may be experienced during periods of low solar energy gain or if there has been
heavy hot water usage. Factors to consider are:
Hot tap not used recently
If a hot tap has not been used for a while, the water in the pipe work between the solar storage tank and
the in-series gas booster may have cooled down. The in-series gas booster will sense the cooler water
and this will cause the burners on the water heater to ignite and boost the water temperature when a hot
tap is first turned on. The burners will extinguish when solar heated water at a temperature higher than
2°C below a water heater preset outlet temperature setting of up to 75°C (i.e. 68°C or above if the preset
outlet temperature setting is 70°C) or higher than 4°C below a water heater preset outlet temperature
setting of 82°C from the solar storage tank reaches the in-series gas booster (refer also to “Fan
Continues to Run after Water Heater Operation Stops” on page 13).
Insufficient sunlight
Insufficient sunlight due to cloudy weather during hotter months or low solar energy contribution in
colder months may mean the in-series gas booster operates more often.
Collectors shaded
If trees or other objects shade the solar collectors or if the glass is dirty, the effectiveness of the solar
collectors will be greatly reduced. Have the trees trimmed or the solar collectors relocated if the
obstruction is permanent or clean the collector glass.
Ensure the glass on your solar collectors is free of dust, salt spray or any other matter, which may
reduce the effectiveness of the solar collectors. If the collector glass becomes dirty, hose down or if the
solar collectors are accessible, wash the collector glass with water and a soft brush when the solar
collectors are cool.
Collector area is too small
For most installations, the number of solar collectors recommended in Rheem literature has been
proven to provide the required solar energy to meet the average family needs. However, in some
circumstances, it may be necessary to install an additional solar collector.
Are you using more hot water than you think?
Are outlets (especially the showers) using more hot water than you think?
Very often it is not realised the amount of hot water used, particularly when showering. Carefully review
the hot water usage. As you have installed an energy saving appliance, energy saving should also be
practised. Adjust your water usage pattern to take advantage of maximum solar gains.
Have your plumber install a flow control valve to each shower outlet, basin and sink to reduce water
Water heater size
Do you have the correct size water heater for your requirements?
The sizing guide in the sales literature and on the Rheem website ( suggests
average sizes that may be needed.
It is the normal operation of the water heater for the fan to continue running after heating of the water is
finished. The fan may run for up to six minutes after the burners extinguish, to prepare for the next ignition.
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