
For parallel piping, see
. Mount the water heater circulator as close as is practicable to the water
heater, and make sure the flow arrow points toward the water heater. The use of shut-off valves is
recommended for future service convenience.
The water heater connection labeled “Out to Boiler” should be piped to the boiler return, piping as close to
the boiler as possible and after any flow control or check valves in the space heating return piping. We
recommend the use of a union and a shut-off valve. The use of a check valve is required to prevent back flow
through the water heater during operation of the space heating system.
3.4 Zone valve system (residential only)
IBC recommends using minimum size 1" pipe and 1" full-port zone valves with a high CV on the water heater
zone to ensure adequate flow.
The water heater connection labeled “In from Boiler” must be piped to the boiler supply piping after the air
purger and grouped with the other zone supplies. The use of a shut-off valve is recommended for future
service convenience.
The water heater connection labeled “Out to Boiler” should be piped to the boiler return piping and grouped
with the other zone returns. We recommend using a union and a shut-off valve. The use of a check valve is
required to prevent back flow through the water heater during operation of the space heating system.
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3.4 Zone valve system (residential only)