Rinnai 37AHA Series Training Manual page 10

Basic Sequence of Operation
Typical Open-Loop Air Handler Operation
• When the thermostat calls for cooling from the A/C, circulation occurs from the condenser
through the evaporator coil
• Air is blown across the evaporator coil moving cool air into structure (no time delay)
• Similarly, when the thermostat calls for heating from the heat pump, circulation occurs from
the evaporator coil through the condenser
• Air is blown across the evaporator coil moving warm air into structure (no time delay)
• If the heat pump cannot adequately heat the structure, the thermostat will call for
emergency heating and initiate flow from the water heater, engaging the air handler
• While the hydronic system is in use, the flow sensor again monitors water usage to ensure
adequate heat is delivered
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Rinnai Corporation Hydronic Air Handler 101 Training Manual