Rheem W2W Series Owner's Manual And Installation Instructions page 9

HOW YOUR WATER HEATER WORKS
To prevent this damage, the pumps for
both sides of the water heater are sized
and supplied by Rheem and the heat
pump is supplied with a flow switch
sensor and a low temperature cut out
switch. The heat pump will terminate its
operation if poor flow rate is sensed or
the cold side outlet temperature or hot
side outlet temperature falls below
5°C.
AUXILIARY BOOST OPERATION
There are two types of auxiliary boost operation, which operate as follows:
ANTIFREEZE AUXILIARY BOOST OPERATION
When freeze protection activates, the heat pump will cease operating. It is then
possible to activate auxiliary heating mode.
In auxiliary heating mode the controller deactivates the heat pump and switches
to an auxiliary gas or electric water heater, if installed and activated in the menu.
A pump circulates water from the storage tanks through the auxiliary water heater
until the set temperature is reached.
When the cold side outlet temperature and hot side outlet temperature rises to
10°C, the auxiliary heating mode is deactivated and the heat pump starts
operating again.
For installations using multiple heat pumps in a master/slave configuration,
activation of antifreeze auxiliary boost operation on any heat pump activates the
auxiliary boost on all LAN connected heat pumps.
BACKUP AUXILIARY BOOST OPERATION
If the heat pump is in fault mode, the controller switches to an auxiliary gas or
electric water heater, if installed and activated in the menu. A pump circulates
water from the storage tanks through the auxiliary water heater until the set
temperature is reached.
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