Hired-Hand Farm Hand Series: Vent Master 16 Stage - Manual (Page 22)

Part No. 4801-5098 Farm Hand Vent Master 19
As you can see, a stage will be placed on the system timer once the temperature rises above 80ºF
(OFF) and will start running 50% (P71) of the time. If the temperature continues to increase
then the run time percentage will also increase toward 90% (P70).
12.5 Variable Speed Stage Operation
Depending on the Farm Hand Vent Master model, you have 0 or 2 variable stages. The Variable stages
can be used in one of two ways: Variable Speed or Progressive Cool Timer. The two options are selected
by the parameters P3. The following sections explain the operation of both options.
12.5.1 Variable Speed Stage Operation (Variable Stage Model Only)
Note: This option applies to stages 1 and 2 of the Variable Stage Farm Hand Vent Master.
The variable speed option (P3=0) allows the user to configure the variable stage to vary the speed of the
fan for their minimum ventilation needs. The following explains the setup and operation.
In this case, the stage timer setting is P3=0 to indicate variable speed operation. The Minimum OnPoint
(OFF) is set for 75ºF, and the Maximum OnPoint (ON) is set for 80ºF. This establishes the temperature
range (75º-80º) over which the speed is varied. The variable speed percentage is set by the "Var/Timer
Pct." parameter as described in Section 5.1. In this example, Var/Timer Pct. is set to 50%. The
Minimum Runtime percentage is set to 40% (P10=40).
Below 75ºF, a fan connected to the variable speed stage will run at 50% speed for 40% of the system timer
(either 2 minutes for a 5 minute timer, or 4 minutes for a 10 minute timer). When the temperature
reaches 75ºF, the fan will run at minimum speed (50%) continuously. As the temperature increases, the
fan speed progressively increases from 50% up to 100% at 80ºF. Above 80ºF, the fan runs continuously
at its maximum speed.
Table 2 Example Of Variable Speed Fan Control
Brief Description Of Variable Speed Fan Control
Percent
100
50
50
100
76 78 80 77 75 79
TEMPERATURE (F)
Graph 2 Variable Speed Fan
Minimum OnPoint
Minimum Speed
Maximum
Maximum Speed
Setting Stage
Sensor Stage
Mode Stage
Timer Minimum
OnPoint Maximum
OnPoint Minimum
Runtime % Motor
Curve Var/Timer
Percentage
Parameter P1 P2 P3 OFF ON P10 P11 N/A
Value 10 02 00 75 80 40 0 50
Option Sensor 1 Cool Stir No Timer Fan begins
Varying
Speed Fan begins
Maximum
Speed Runtime
40% Standard
single
phase Refer to
Section 5.1