Rheem Water Star Owner's Manual And Installation Instructions page 22

CONNECTIONS – PLUMBING
A full flow isolation valve, such as a gate valve or ball valve, must be installed
on the water line from the continuous flow gas water heater to the Water Star
water heater.
If there is no expansion control valve installed, then the non return valve must
be installed between the continuous flow and Water Star water heaters. An
acceptable arrangement is shown in the diagram
Water Star with Continuous Flow Water Heater
If an expansion control valve is installed, then this must be installed before the
continuous flow water heater. The non return valve must be installed before the
ECV and MUST NOT be installed between the continuous flow and Water Star
water heaters. An acceptable arrangement is shown in the diagram.
Water Star with Continuous Flow Water Heater
"Hot Water Delivery"
Refer also to
page 16.
Water Connections – without ECV
Water Connections – with ECV
on page 17 and to
22
"Mains Water Supply"
on