Hired-Hand Farm Hand Series: POWER VENT INLET - Manual (Page 5)

Part No. 4801-0149 Rev 1-01 Farm Hand Power Vent 3
Let’s assume that you have this controller installed in your house, and you decide you want pressure to be
kept a little bit lower. You walk to the controller, press and release the mode button, watching the green
lights until the “Target High Pressure light” is lit. If you look at the display now, you see the present setting
for the high limit. To lower it, press and release the minus (-) button until you see the high limit you want.
The controller will now start operating using your new limit. Set your low limit the same way.
6. Why a Pressure Controller?
The Farm Hand Power Vent is used to control vent inlets in agricultural enclosures. Maintaining a slight
negative pressure inside a building ensures that air flows in evenly from all openings in the building. As
static pressure increases, the speed of the incoming air increases.
It is important to set the pressure at the appropriate level to ensure maximum efficiency. Too little vacuum,
and the livestock could suffer from drafting, and temperature shock. Too much vacuum, and fan efficiency
is reduced, increasing the levels of moisture, and ammonia in the enclosure, also driving up electricity costs.
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 that you need 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 OUTSIDE temperature.
(Since, after all, outside air is what you are bringing into the house.) If outside temperature is warm, it will
allow you to take in a large volume of slow moving warm air (low static pressure), but when outside air is
cold, the unit will adjust to allow only a low volume of fast moving cold air (high static pressure).
Following are two examples of ramping: