66389-BIM-C-1208
32
Johnson Controls Unitary Products
OPERATION
SEQUENCE OF OPERATIONS OVERVIEW
For the DW series of units, the thermostat makes a circuit
between "R" and "Y1" for the first stage of cooling.
The call is passed to the unit control board (UCB), which then
determines whether the requested operation is available and,
if so, which components to energize.
For gas heating, the UCB monitors the "W1" call but does not
handle the operation of the gas furnace. An ignition control
board controls the gas heater operation. For electric heat
units, the UCB passes the call to the electric heater. In both
cases, when the "W1" call is sensed, the indoor air blower is
energized following a specified heating delay.
If at any time a call for both heating and cooling are present,
the heating operation will be performed. If operating, the cool-
ing system is halted as with a completion of a call for cooling.
Heating always takes priority.
COOLING SEQUENCE OF OPERATION
CONTINUOUS BLOWER
By setting the room thermostat fan switch to "ON," the supply
air blower will operate continuously.
INTERMITTENT BLOWER
With the room thermostat fan switch set to "AUTO" and the
system switch set to either the "AUTO" or "HEAT" settings,
the blower is energized whenever a cooling or heating opera-
tion is requested. The blower is energized after any specified
delay associated with the operation.
When energized, the indoor blower has a minimum run time
of 30 seconds. Additionally, the indoor blower has a delay of
10 seconds between operations.
TABLE 21: ADDITIONAL STATIC RESISTANCE
CFM
Cooling Only
1
Economizer
2
3
Electric Heat KW
18
24
36
54
3700
0.20
0.04
0.18
0.21
0.22
0.26
3900
0.23
0.04
0.20
0.23
0.24
0.28
4100
0.25
0.04
0.22
0.25
0.26
0.31
4300
0.28
0.05
0.24
0.28
0.29
0.34
4500
0.30
0.05
0.26
0.30
0.31
0.37
4700
0.33
0.05
0.29
0.33
0.34
0.40
4900
0.36
0.05
0.31
0.35
0.37
0.43
5100
0.39
0.06
0.34
0.38
0.40
0.46
5300
0.42
0.06
0.37
0.41
0.43
0.49
5500
0.45
0.06
0.40
0.44
0.46
0.53
5700
0.48
0.06
0.43
0.47
0.49
0.56
5900
0.52
0.07
0.46
0.50
0.53
0.59
6100
0.56
0.07
0.49
0.53
0.56
0.62
6300
0.60
0.07
0.53
0.56
0.59
0.65
1.
Add these resistance values to the available static resistance in the respective Blower Performance Tables.
2.
Deduct these resistance values from the available external static pressure shown in the respective Blower Performance Table.
3.
The pressure drop through the economizer is greater for 100% outdoor air than for 100% return air. If the resistance of the return
air duct system is less than 0.25 IWG, the unit will deliver less CFM during full economizer operation.
TABLE 22: MOTOR SHEAVE DATUM DIAMETERS
1VM50x7/8
(3 HP Motor)
1VP56x1-1/8
(5 HP Motor)
Turns Open
Datum
Diameter
Turns Open
Datum
Diameter
0
4.4
1
5.3
1/2
4.3
1-1/2
5.2
1
4.2
2
5.1
1-1/2
4.1
2-1/2
5.0
2
4.0
3
4.9
2-1/2
3.9
3-1/2
4.8
3
3.8
4
4.7
3-1/2
3.7
4-1/2
4.6
4
3.6
5
4.5
4-1/2
3.5
5-1/2
4.4
5
3.4
6
4.3
