WattMaster Water Source Heat Pump, Installation & Operation Manual

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Section 1
WattMaster WHP
1-6
Design Guide
WHP Sequence of
Operation
HVAC Mode of Operation
There are four possible modes of operation. These are Cooling Mode, Heating Mode,
Vent Mode, and the Off Mode. The HVAC mode of operation is calculated the same way
in both occupied and unoccupied modes of operation.
Off Mode The schedule is off and no overrides are active. There is no heating or
cooling demand in the space. Under these conditions, all outputs will be
off and the analog output will be set to 0.0 vdc.
Vent Mode No heating or cooling demand exists during the occupied mode of
operation. The fan will be on if the WHP is programmed for Constant Fan
operation. The compressor demand request will not be sent to the Loop
Controller. If no WHP units are sending a request, the Loop Controller
will discontinue operation after 15 minutes.
Cool Mode A cooling demand is generated when the space temperature rises half the
amount of the Deadband Setpoint above the currently active Cooling
Setpoint. The space is considered satisfied when it drops that amount
below the Cooling Setpoint.
Heat Mode A heating demand is generated when the space temperature drops half the
amount of the Deadband Setpoint below the currently active Heating
Setpoint. The space is considered satisfied when it rises that amount above
the Heating Setpoint.