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Appendixes
6.7 Navien H
2
Air Add-on Controller Kit (Optional)
The Navien H2Air is an add-on controller for the water heater. It adds input and
output functions to the water heater for a combination application where space
heating and domestic hot water (DHW) are supplied simultaneously. With this add-
on controller, a thermostat (1 or 2-stage) and an outdoor sensor can be installed
along with a hydronic air handler to add space heating functionality to the system.
6.7.1 Basic Principles
The following diagram shows the basic operation of the heater system with the Navien H2Air add-on controller.
NOTICE
Do not configure the system for DHW recirculation when it is configured to run an air handler using the
H2Air add-on controller. DHW recirculation and Navien H2Air configurations cannot be used at the same
time.
NHW700-AI/AE
Series Water Heater
Heat Demand
Output
Space Heating
Supply
Check
Valve
Expansion
Tank
Internal Pump
Flow Switch
Cold Water
Supply
Space Heating
Return
Mixing Valve
DHW Supply
Outdoor Sensor
Thermostat
