Rheem RTGH-RH10DV Service Manual page 11

Chapter 1 Product Characteristics
Operating Principle (Standard/External Mode)
Standard Mode
1. Only POTABLE water may be plumbed through
the water heater.
2. The water heater cannot be used for space
heating applications.
3. Expansion tank is required if a backflow
preventer is installed.
4. Isolation valve kits are recommended for this
installation.
External Recirculation mode
The recirculation pipe must be installed in the field in
order to use 'External Recirculation Mode'.
This mode allows the water heater to recirculate
heated water through the system and additionally
serves as a freeze protection function.
When using external recirculation mode with
the built-in pump, check the following maximum
recirculation pipe lengths including fittings (3/4"
pipe is recommended):
-1/2" Pipe- 200' (60m) of equivalent length
-3/4" Pipe- 500' (150m) of equivalent length
Lengths in excess of these limits will require an
external recirculation pump.
Air & Gas
Mixing
Burner
Primary heat
exchanger
Secondary heat
exchanger
Recirculation
Pump
Pressure Relief Valve
Secondary heat
Recirculation
Recirculation
Pump
Pump
Pressure Relief Valve
Pressure Relief Valve
Recirculation Line
Gas
Backflow Preventer
(optional)
Expansion Tank (Install
according to local code)
Air & Gas Air & Gas
Mixing
Mixing
Burner
Burner
Primary heat
Primary heat
exchanger exchanger
Secondary heat
exchanger
exchanger
Gas
Gas
Expansion Tank (Install
Expansion Tank (Install
according to local code)
according to local code)
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