850 Communicating Wi-Fi Comfort Control
11-HD14D1-9-EN 13
6. Basic Operation
6.1 PI Control
The 850 Control uses proprietary control schemes to
provide comfort and energy efficiency. The Control senses
indoor temperature and determines capacity needed based
on the following parameters:
•
Mode of operation
•
Proportional Error - distance from setpoint
•
Integral Error - Time away from setpoint
72º
B
C
D
Set Point
Temperature
2 Seconds
Integral Error
Room
Temperature
A
B + C + D... = Integral Error
A = Proportional Error
6.2 Load Value - Heating
The 850 Control uses proportional plus integral error to
determine the amount of capacity required. The calculated
capacity is displayed as load value. Load Value is a numerical
representation of the needed capacity to maintain setpoint.
The load value range is dependent on the applied system.
0-100
Single Stage Heat Pump Only
0-200
Two State Heat Pump Only
0-200
Single Stage Heat Pump + 1 Stage Electric/Wet Heat
0-300
Single Stage Heat Pump + 2 Stage Electric/Wet Heat
0-400
Single Stage Heat Pump + 3 Stage Electric/Wet Heat
0-300
Two Stage Heat Pump + 1 Stage Electric/Wet Heat
0-400
Two Stage Heat Pump + 2 Stage Electric/Wet Heat
0-500
Two Stage Heat Pump + 3 Stage Electric/Wet Heat
0-100
Single Stage Indoor Heat Only
0-200
Two Stage Indoor Heat Only
0-300
Three Stage Indoor Heat Only
0-175
Single Stage Heat Pump + 1 Stage Gas/Oil Heat
0-275
Single Stage Heat Pump + 2 Stage Gas/Oil Heat
0-375
Single Stage Heat Pump + 2 Stage Gas/Oil Heat
0-275
Two Stage Heat Pump + 1 Stage Gas/Oil Heat
0-375
Two Stage Heat Pump + 2 Stage Gas/Oil Heat
0-475
Two Stage Heat Pump + 3 Stage Gas/Oil Heat
6.3 Load Value - Cooling
0-100 Single Stage Compressor
0-200 Two-Stage Compressor
A Load Value of 50 represents a request of 50% demand
for single stage cooling units (“Y”) or 50% demand for stage
one of multistage cooling units (“Y1”).
A Load Value of 150 represents a request of 100% demand
for stage one (“Y1”) and 50% demand of stage two (“Y2”)
for multistage cooling units.
6.4 Duty Cycles (non VSPD systems)
Indoor temperature control is achieved by duty cycling the
equipment when the load value is less than 100% of the
current stage of operation. The duty cycle rate is dependent
on the calculated load value.
The duty cycle chart below indicates the number of cycles
at 50% load (i.e. LV = 50).
1 Hour
6 CPH
2 CPH
As with all PI-based controls the indoor temperature will
fluctuate above and below the user selected setpoint to
maintain comfort in the space. Adjusting the factory set
CPH (Cycles per Hour) can affect how tight the Control
operates around the setpoint. The CPH can be adjusted in
the Installer Setup>Equipment Settings (2 – 6 CPH)
•
Factory default for compressor operation is 3 CPH
•
Factory default for indoor heat is 5 CPH
Effects of changing the cycle rates
Lower CPH results in longer run cycles with less cycling
but the indoor temperature may deviate above and below
setpoint.
Higher CPH results in tighter indoor temperature control
but shorter, more frequent cycles.
6.5 Overshoot Clamp
The 850 Control will enforce an “off cycle” anytime the
control overshoots more than 2.5°F. Once the indoor
temperature is within 0.75°F of setpoint an “on cycle” is
allowed dependent on load value and minimum off times.
Actual Temperature
75º
74.25º
72.5º
Cooling Overshoot Clamping Example
OFF Cycle Enforced ON Cycle Allowed
