Hired-Hand Farm Hand Series: Vent Master 24 - Manual (Page 6)

Part No. 4801-5124 rev 10-03 Farm Hand Vent Master 24 4
7. Pressure Ramping (Optional) Explanation
High Volume of Slow Warm Air
Low volume of fast moving air enters the vents and is "thrown"
to the ceiling, where it is slowed, and warmed by the mixing with
the warmer air in the top of the enclosure before settling down
to the bottom of the building.
The above illustrations show the need for a different air flow rate when the temperature changes. This
is accomplished with the ramping feature.
Ramping allows you to set a band of pressure to be maintained, taking into account the OUTSIDE
temperature. (After all, outside air is what is flowing into the house.) If the outside temperature is
warm, it will allow taking in a large volume of slow moving warm air (low static pressure), but when
outside air is cold, the Vent Master 24 will adjust to allow a low volume of fast moving cold air (high
static pressure).
Using figures from the chart above; the controller was programmed as follows:
P21 = Pressure Differential 0.02” w.c.
P30 = Ramping Mode ON
P31 = High Temperature Limit 80°F
0.12
0.10
0.08
0.06
0.04
0.02
0
Temperature (F)
Negative
Pressure
("w.c.)
0
10 20 30 40 50 60 70 80 90 100 110
Above Target High Pressure
Vent Machine Opens
Below Target Low Pressure
Vent Machine Closes
Acceptable Target Pressure
No Machine Operation
Pressure Differential
Target Pressure