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3.4.4 System Application – External Recirculation
External Recirculation
The following diagram shows the recirculation system's basic operation of an NHW700 water heater system with
the dedicated return line.
Ball Valve
Expansion Tank
Check Valve
City Water Supply
External Recirculation with Hotbutton (Optional)
The Navien HotButton kit is an add-on input board for the water heater. It adds signal
input functions to the water heater for more efficient DHW hot water recirculation
functionality.
With the HotButton kit, DHW recirculation is carried out exactly when the actual demands
arise. This prevents energy loss caused by unnecessary operation of the burner and pump
throughout the day.
The HotButton kit can receive signals from multiple push buttons installed in various
areas and performs optimal DHW recirculation only when there is a demand for hot water.
The following diagram shows the basic operation of an NHW700 water heater recirculation system with the
HotButton Kit.
NOTICE
The Navien HotButton can be used ONLY with a water heater system configured for DHW recirculation.
30
Installing the Water Heater
To Cold Water Inlet
To Cold Water Inlet
Return Water
DHW Supply
(To Hot Water Fixtures)
Cold Water Line
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