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DN-Series Integrated Programmable Controls
DOAS
58
6.5.2.2 Heat Pump 2-Stage Cooling Operation
This type of cooling cycles two stages of cooling to maintain the cooling setpoint. You must
set a prop band value. This value represents 100%; the wider the prop band the slower the
response. Then you specify the “on point” for stages one and two in percentages. Stage one
will turn off at setpoint and stage two will turn off at the on point for stage one. There is also a
minimum on and off time to prevent over-cycling.
If in cooling mode, and the unit calls for cooling, it puts the tempering mode output used for
a reversing valve, in the cool position and after a delay, will turn the compressor on and off to
maintain the cooling setpoint.
Stage 1 turns on a 25% and
Stage 2 at 75% of prop band
Stage 2 turns off at 25% and
Stage 1 at 0% of prop band
Proportional Band
Se
Proportional Band
Setpoint
STAGE 1
OFF
TEMPERATURE
STAGE 2
OFF
0%
25%
75%
100%
STAGE 1
ON
STAGE 2
ON
Example:
In this case 4°F = 100% which means that 1°F = 25%, which makes our calculation
easy. With the default settings, stage 1 turns on at 66.2 + 1 = 63.2. Stage 2 turns on at 66.2 +
3 = 65.2.
TEMPERING CONTROL
