f
manually adjusted panels in the feed aisle door. As
fans cycle on and off or variable speed fans ramp up
and down in speed, the fixed opening does not
accommodate the changing air flow needs, and proper
air distribution is not maintained. The self-adjusting
inlet baffle is ideal for providing adequate air volume
and mixing for mechanically ventilated veal calf
rooms. These inlets are described in fact sheet G 92
Self -Adjusting Baffle Inlet to Improve Air
Distribution. One large baffle inlet assembly (Figure
1) over each feed aisle entry door is advisable to
supplement the feed aisle door inlet. A second and
third assembly to each side can provide hot weather
ventilation when some air flow over the calves is
desirable for cooling.
Using a 50-calf room of two rows of stalls facing a
central feed aisle as an example, an inlet design would
look like Figure 2. Cold weather, minimum ventilation
is provided by the door panel, which directs air along
the feed aisle and virtually eliminates any cold air draft
on the tethered calves. As weather warms, additional
fans turn on and the self-adjusting baffle inlet above the
feed aisle door opens to provide additional inlet area.
This single baffle inlet should be sized to provide inlet
area, in concert with the door panel, for cold and mild
weather conditions. Air will be directed along the
ceiling where it can mix with warm room air before
reaching the calves. Once hot summer weather arrives,
the two additional self-adjusting baffle inlets located
over the calf stalls are unlocked to provide inlet area
needed for large summer air exchanges. These two
larger baffle inlets have their baffles locked into a
closed position most of the year and are only opened
during hot weather.
G 93
Current Situation
Overview of Solution
Figure 1. Self-adjusting baffle inlet for use with preheat room adjacent to livestock room.
Top
Hinge support
Continuous baffle hinge
End board
Metal
rod
Rigid
insulation
board
Bottom horizontal
air flow deflector
End
board
College of Agricultural Sciences
Agricultural and Biological Engineering
Cooperative Extension
An Equal Opportunity University
College of Agricultural Sciences, U.S. Department of Agriculture, and Pennsylvania Counties Cooperating D-108
Figure 2. Self-adjusting baffle inlet size and placement retrofit design (50 calf room example).
18"x75" Summer Baffle Inlet
12"x70" Baffle Inlet
18"x75" Summer Baffle Inlet
Locked closed
during winter
Fixed 1 sq. ft. opening
Minimum ventilation cold
weather w/ smallest calves
Door panel 30"
"storage space"
30" Door panel
38" total panel
opening
18"
35"
4"
8"
8-9' Ceiling height
Maximum opening for
largest calves in cold
weather.
68"
80" Doorway Figure 3. Plan view of example 50-calf room.
Stacked
fans
3 Self-adjusting
baffle inlets
PREHEAT ALLEY
heaters
FEED AISLE
25 Stalls per row
Ventilation Example Calculations
50 veal calves; 2-row, central feed aisle room off
preheat aisle as shown in Figure 3.
Cold weather; smallest calves at 100 pounds each.
Fan capacity: 50 calves x 10 cfm/cwt = 500 cfm
Inlet size:
50 calves x 2.75 sq. in./100 pounds = 138 sq. in.
1 sq.ft.
Cold weather; large calves at 450 pounds each.
Fan capacity:
50 calves x 10 cfm/cwt x 4.5 cwt = 2250 cfm
Inlet size:
50 calves x 2.75 sq. in./cwt x 4.5 cwt = 619 sq. in. =
4.3 sq. ft.
Table B provides inlet area and fan capacity needed for
an example 50-calf room housing calves from 100 to
500 pounds during cold, mild, or hot weather
conditions. Figure 7 shows the inlet area and fan
capacity needed in the 50-calf room for various weight
calves during each season.
Year-round Ventilation Inlets
Cold Weather
The minimum winter ventilation needs for moisture
removal in the calf room is estimated at 10 cfm/100-
pounds (cwt) of calf and can be met using an adjustable
panel in the feed aisle entry door. A permanent
opening of 1 sq. ft. matches the inlet area needed for
minimum cold weather ventilation rate for 50 of the
smallest calves (100 pounds each). In the example, an
8-inch tall by 18-inch wide inlet is provided (Figure 2).
As calf size increases to 500 pounds, the door panel is
opened wider to match calf growth increments of 50-
pounds. This matches the increased fan air exchange
rate needed for larger calves. The winter ventilation
rate controls moisture and air contaminant (ammonia,
odor, etc.) removal. It provides a minimum air
exchange to achieve these functions while recognizing
that supplemental heat is being used to warm room air.
One inherent disadvantage of a single inlet at one
end of the room is that calves near the door panel are
exposed to fresh air while calves unfortunate enough to
be located closer to the fans are continually breathing
stale air. As long as room length (feed aisle length) is
kept below 75 feet, this should not be a problem. The
50-calf room meets this criteria with 25 calves per row
in 24- to 26-inch wide stalls (larger stalls would be
used for the heavier calf market weight of 400 to 500
pounds) for a 50- to 55-foot-long room.
Outside air inlet
to preheat alley
Ventilation Sizing Review
cold
10 cfm/100-pound (cwt) calf
mild
20 cfm/cwt
hot
50 cfm/cwt
Provide 1.7 to 2.0 square foot of inlet area per
1000 cfm of fan capacity to maintain a 0.05-
inch static pressure difference between outdoors
and the calf room interior.
This works out to:
cold
2.75 sq. in inlet/cwt
mild
5 sq. in inlet/cwt
hot
13 sq. in. inlet/cwt
Table A provides inlet area and fan capacity
needed per calf to meet these requirements for
calves growing from 100 up to 500 pounds
during cold, mild, or hot weather conditions.
Figure 6 shows the inlet size needed per calf
depending on ambient temperature (weather)
and calf weight. Mild Weather
As weather warms, more fan capacity is needed,
estimated at 20 cfm/cwt, for temperature control in the
room, and hence, more inlet area is needed. Additional
inlet area, beyond that minimum area provided by the
open door panel, will be supplied by the self-adjusting
baffle inlet box above the door (Figure 4). The baffle
inlet box should be no more than 12-inches high to
encourage air to discharge near the ceiling for more
effective fresh air throw into the room. Place the
baffle inlet box flush against the ceiling. A box 12-
inches high and 70-inches wide, a typical feed aisle
width, will provide enough inlet area for mild weather
ventilation rates for all but the largest (500-pound)
calves on the warmest spring or fall days. An option is
to be able to draw air from the preheat aisle for
youngest calves and from the attic for older calves
which do not need the preheated air (Figure 5 and
Drawing Set C).
Figure 4. Cross section of
self-adjusting baffle inlet
used with preheat room.
Figure 5. Cross section of self-
adjusting baffle inlet with option for
using attic air or preheat room air.
Insulated ceiling
LIVESTOCK
ROOM
ATTIC SPACE
Long "shelf" to
assure air is
directed
Wall
PRE-HEAT
ROOM
12 " maximum
Insulated ceiling
LIVESTOCK
ROOM
Self-adjusting
baffle inlet
assembly
Wall
ATTIC SPACE
Optional inlet
PRE-HEAT
ROOM
Hot Weather
As weather changes to hot summer conditions,
even more fans are used for temperature control, at 50
cfm/cwt, so even more inlet area is needed. This is
provided by the two self-adjusting baffle inlets located
to the sides of the feed aisle. They are larger than the
central inlets and provide benefit in directing some air
flow over the calves for convective, breezy cooling on
hot days. Evaporative cooling fogger nozzles may be
added near these inlets for enhanced cooling. These
larger inlets are fixed shut most of the year and only
used during summer. They need to be 18-inches high
by 75-inches long to provide adequate inlet area for
the maximum air flow rates needed in the 50-calf
room example. During hot weather, the feed aisle
door panel is fixed in its full open position, the central
aisle 12-inch by 70-inch baffle is operating, plus the
two large summer baffles. When cool weather returns
in the fall, the two large summer inlet baffles should
be fixed shut, and only the central aisle baffle inlet and
the door panel opening are used. Fans
Provide fans that supply the required range of air
capacity needed for moisture and excess heat removal.
C
ontrols are necessary to maintain desired room
temperature in concert with supplemental heaters.
Using Table B for the 50-calf room example:
Stage 1
Minimum continuous ventilation, cold weather
Variable speed, 16-inch fan
Do not operate below 50% speed.
700 to 2500 cfm provided as calves grow 100 to 500
pounds.
Stage 2
Mild weather ventilation
Variable speed, 18-inch fan
900 to 3800 cfm as temperature increases
(3400 to 6300 cfm total stages 1 + 2)
Stage 3
Hot weather ventilation
Variable speed 24-inch fan; probably operated as on/off
Additional 5600 cfm
(11,900 cfm total stages 1 + 2 + 3)
Stage 4: Heat
1000 Btu/calf estimate. Depends on insulation in
building and ventilation rate.
Provide 1000 Btu/calf heat in each calf room: 50,000
BTU heater.
Provide one similar-sized heater in the preheat alley.
Summary
Adjustable inlets help provide proper fresh air
distribution in veal calf housing. Manually adjusted
inlets are not repositioned often enough to provide
appropriate conditions when fans are changing speeds
and/or cycling on and off. The self-adjusting inlet
baffle assembly