WattMaster Water Source Heat Pump, Installation & Operation Manual

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WattMaster WHP
Section 1
Design Guide
1-13
Staged Heat Addition
Heat Addition is staged up based on a different deadband level for each stage. Basically,
if the user programmed a 2° deadband, then the first stage could activate at the setpoint,
stage 2 would activate 2° below the setpoint, stage 3 would activate 4° below the setpoint,
etc...
Staging down is calculated in the same manner, except the water temperature would need
to increase above the setpoint by the deadband amount. If stage 3 was activated at 4°
below setpoint, it would de-activate when the temperature rises to within 2° of setpoint,
stage 2 would de-activate at setpoint and stage 1 would de-activate 2° above setpoint.
A user defined staging up and down interval must be met before any heat addition stages
can be added or removed. If the selected Water Temperature is below the current staging
level and the timer has been satisfied, an additional stage can be added, up to the
maximum available 8 stages. If the selected Water Temperature is above the staging
down level and the timer has been satisfied, a stage can be removed.
Proportional Heat Addition
If the Water Temperature is below the addition setpoint, a Boiler Enable relay is
activated. If the Water Temperature rises 1° above the setpoint the Boiler Enable relay is
de-activated.
At a user defined rate, the analog output signal is proportionally controlled from 0.0 VDC
at 1° above setpoint to the full 10.0 VDC signal as the water temperature drops below the
setpoint by the user defined deadband amount. If a 5° deadband was entered, the
maximum voltage would be reached at 4° below the setpoint and the minimum voltage
would be set at 1° above the setpoint. Since this is strictly proportional control, at 1.5°
below setpoint the controller would set 5.0 VDC since that would be half the deadband
amount.