A Rheem 874a20NF model may be used as an in-series booster water heater to a solar preheat water
heater. When the inlet water temperature is 58°C or higher the fan and burner will not
operate despite water flowing through the heat exchanger. When the inlet water
temperature is less than or equal to 57°C the burner will fire and boost the outlet
temperature to the preset outlet temperature setting provided the flow rate is greater than
3 litres per minute
In this application the preset outlet temperature setting of the heater must be set at 70C to
comply with the requirements of AS 3498.
It may be required by regulations that an approved
temperature limiting device be fitted on 60°C models
(244, 274, 874 series). Where a tempering valve is
fitted and there is not a separate untempered line for
the kitchen or laundry areas, the kitchen temperature
controller will be able to display temperatures above
50°C however the delivered water temperature at the
tap will be that set by the tempering valve which will
be no hotter than 50°C.
To enable delivery of hot water at temperatures
above 50°C a separate untempered line must be
provided that supplies hot water exclusively to
kitchen and laundry areas
