Tekmar Invita Installation, Operation And Maintenance Manual page 29

Cooling Differentials
The first and second stage cooling have adjustable differentials and time delay setting to determine
when the stage turns on, and shut off when the room temperature reaches 0 .5 and 0 .0°F (0 .25 and
0 .0°C) above the Cool To setting respectively .
Heat Pump Balance Point
An air source heat pump's Coefficient of Performance (COP) declines with falling outdoor air tempera-
ture . The Balance Point is the outdoor temperature at which it is more economical to shut off the heat
pump (relays Y1 and Y2) and operate the backup heating equipment (relays W1 and W2) .
Dual Fuel
Dual fuel systems include a heat pump together with a backup heat source such as a furnace or a
hydronic fan coil . When Dual Fuel is set to on, the heat pump (relays Y1 and Y2) is shut off whenever
the backup heating equipment (relays W1 and W2) is operating .
Warm Weather Shut Down (WWSD)
The heating system can automatically shut off based upon the outdoor temperature and the WWSD
setting . This provides a convenient way to shut off the heating system .
Cold Weather Shut Down (CWSD)
The cooling system can automatically shut off based upon the outdoor temperature and CWSD
setting . This prevents unwanted cooling during the winter .
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