More than two or three taps in use at the same time may cause a decrease in the hot water flow from the
taps. This can also be evident if the water heater has been installed as an in-series gas booster to a solar
water heater and the solar heated water is at a low temperature.
Are there more than two or three taps open, or are appliances such as a dishwasher or washing
machine, in use at the same time?
Ensure only two or three taps or appliances are on at the one time.
Check the flow of the water from one tap, e.g., the shower.
The shower should be adjusted so the hot tap is fully open.
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 58°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 of 58°C or higher 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 43).
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?
Is one outlet (especially the shower) 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 family’s hot water usage. As you have installed an energy saving appliance, energy saving should
also be practised in the home. Adjust your water usage pattern to take advantage of maximum solar
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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