11/19/2009
Poultry house ventilation system
`
Basically consists of
exhaust fans and air inlets.
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Exhaust fan draw in fresh
air
Poultry House Ventilation System
Design
Michael Czarick III
The University of Georgia
Poultry house ventilation system design
`
How much exhaust fan capacity should a
house have?
Basically consists of
exhaust fans and air inlets.
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`
Exhaust fan draw in fresh
air
Inlets direct the fresh air to
where we want it to go.
go
Exhaust fan capacity rule of thumb
Example:
`
60’ X 300’ broiler/turkey house
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`
60’ X 300’ X 7 = 126,000 cfm (25 – 24” fans)
Minimum exhaust fan capacity for a power-ventilated
broiler/turkey house:
`
7 cfm per square foot of floor space (130 m3/hr per m2)
`
`
This should ensure that there is no more than a 5oF (2.7oC) increase
from the inlet to the exhaust fans
4 – 5 cfm per square foot of floor space for house which is
curtain-ventilated during hot weather
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11/19/2009
This is minimum…
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Heat produce by broilers has increased
approximately 20% in the last 20 years.
The typical U.S. broiler/turkey house:
`
`
8 – 10 cfm per square foot of floor space.
60’ X 300’ = 144,000 – 160,000 cfm
50 years ago
30 years ago
Today
Turkeys have changed as well…
What type of fan should a house be
equipped with?
Exhaust fan selection criteria
Exhaust fan selection criteria
1.
To obtain desired air exchange rate exhaust fan capacity
must be determined at a minimum static pressure of
0.10” (25 Pa).
Energy efficient
2.
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It is not how much power a fan uses…it is how many cubic
feet per minute it can move with each watt of power:
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`
`
Cfm/watt
The higher the rating…the lower your operating costs will be.
Desired energy efficiency rating
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Should have an energy efficiency of at least 20 cfm/watt
@0.10” (34 cmh/watt)…..ideally +20.8 cfm/watt (35 cmh/watt)
or better
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Not only do we want a fan that is energy
efficient, we want a powerful fan as well.
Exhaust fan air flow ratio
3.
`
Fan output vs. static Pressure
(48” fans, between 20,000 and 22,000 cfm)
`
An indicator of how well the fan will hold up to high static
pressures caused by:
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Dirty fan shutters
Clogged inlet screens
Cfm
m
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Air flow ratio = air flow (0.20”)/ airflow (0.05”)
26,000
24,000
22,000
20,000
18,000
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
0
0.05
0.84
Not only do we want a fan that is energy
efficient, we want a powerful fan as well.
An indicator of how well the fan will hold up to high static
pressures caused by:
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`
`
Dirty fan shutters
Clogged inlet screens
Winds
Wind p
pressure (in)
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0.84
0.15
0.2
Static Pressure
0.86
0.74
0.25
0.76
0.3
0.35
0.67
A fan with a high air flow ratio is less
affected by the wind
Exhaust fan air flow ratio
3.
0.1
0.2
0.18
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0
5
10
15
20
Wind speed (mph)
Fan output vs. static Pressure
(48” fans, between 20,000 and 22,000 cfm)
`
Cfm
m
This is a serious problem with variable
speed fans!
Air flow ratio = air flow (0.20”)/ airflow (0.05”)
26,000
24,000
22,000
20,000
18,000
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
0
0
0.05
0.84
0.1
0.84
0.15
0.2
Static Pressure
0.86
0.74
0.25
0.76
0.3
0.35
0.67
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Air flow ratio
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Minimum acceptable
Ideal
Fan performance information is available at
= 0.73
= 0.78 or higher
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WWW.BESS.UIUC.EDU
Estimated initial fan cost
Exhaust fan selection criteria
60’ X 300’ house with 126,000 cfm of fan capacity
Size
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`
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Keep small fans to a
minimum
They are very effective for
minimum ventilation but…
Small fans are a very poor
investment:
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`
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Fan C
Cost ($)
4.
Higher initial cost
Higher operating cost
Higher maintenance cost
$12,000
$11,000
$10,000
$9,000
$8,000
$7,000
$6,000
$5,000
$4,000
$3,000
$2,000
$1,000
$0
12
24
36
48
60
Fan Size (“)
Fan size and energy efficiency
Fan operating cost
(the larger the fan the more energy efficient it tends to be)
(100,000 cfm for 24 hours @ $0.10 per Kw*hr)
Energy Efficie
ency (cfm/watt)
23
$29.00
$27.00
$25.00
$23.00
$21.00
$19.00
$17.00
$15.00
$13.00
$11.00
$9.00
$7.00
$5.00
21
19
17
15
13
11
9
7
5
12
24
36
Fan Size (“)
48
60
12
24
36
48
60
Fan Size (“)
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This does not mean you can’t install a few
small fans but…
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The optimal exhaust fan system stages from small to large
fans quickly:
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Two - four 24” fans – minimum ventilation fans
Two - four36” fans – moderate weather
Then 48” fans or larger for the remainder of the required fan
capacity
it – hot
h t weather
th
Another advantage of keeping the number of
small fans to a minimum
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Reduces the potential for shutter air leakage
100.0°F
100
½ the shutters… ½ the cold spots
90
80
70
60.0°F
Cold spots near exhaust fans
Problems with leaky shutters can be further
reduced by placing exhaust fans in groups
Fan shutter leakage
Minimizing cold spots
Leakage exits adjacent minimum ventilation fans
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11/19/2009
The fact is that fans do not have to be
evenly spaced down the length of the house
Poultry house with a single fan and four air
inlets
Poultry house with two fans and air four
inlets
Poultry house with a single fan and eight air
inlets
Poultry house with a single fan and 16 air
inlets
Poultry house with a single fan and 16 air
inlets
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11/19/2009
Poultry house with a single fan and 16 air
inlets
.08”
.08”
.08”
.08”
.08”
.08”
.08”
.08”
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
950 ft/min
Outside
But you MUST establish a negative pressure if
you want to gain control over the environment
Ventilation system design
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`
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Chimney fans?
It is very important to realize that though fan placement
can be of some importance…
Inlet design/placement is by far, more important when it
comes to maintain proper environmental control
+80% of ventilation system design is proper inlet design
and placement maybe 20% or less is exhaust fan
placement
Chimney fans with poor inlets
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11/19/2009
Chimney fans with poor inlets
Poor side wall inlet
Cool side wall
Poor conditioning of incoming air
Air inlet system design
Air inlet capacity
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How much inlet area should a house have?
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General rule of thumb:
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`
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1 square foot for every 750 cfm of exhaust fan capacity.
or
1 square meter for every 4,800 m3/hr
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11/19/2009
Air inlet example:
40’ X 300’ with 84,000 cfm (7 cfm/ft2)
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Inlet area = 84,000 cfm / 750 cfm
= 168 square feet (16 m2)
If the house had a single continuous inlet…
It is specifically designed to bring in just enough air to
maintain air quality during very cold weather:
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`
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For optimal control a modern poultry house should have
a minimum of two inlet system….ideally three
Each inlet system is specifically designed to be used to
obtain specific objectives
2) Moderate weather inlet system
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Designed to control house temperature during moderate
weather.
Maximize heating of incoming cold air
Distribute fresh air throughout the house evenly
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Without causing drafts
With t causing
Without
i excessive
i ffuell usage
3) Hot weather inlet system
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Inlet width = total inlet area/ house length
= 168 ft2/300 ft
= 0.56’ feet or 6” or 15.2 cm
1) Cold weather inlet system
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Air inlet system(s)
Minimum ventilation inlet system
Designed to maximize bird heat removal
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Produce high air velocities over the birds to maximize heat
removal
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11/19/2009
Minimum ventilation inlet system
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Specifically designed for use for very cold weather for use
with just a few exhaust fans…minimum ventilation fans.
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1 – 2 cfm per square foot.
60’ X 300’ X 1.5 = 27,000 cfm
Might consist of only 20 to 30 inlets
Minimum ventilation inlet guidelines
Located towards the center of the house
1)
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`
That is where your hottest air tends to accumulate
Furthest distance from the birds
99.0°F
99.4
97.4
95
94.2
90
92.1
89.6
86.1
85
83.6°F
Example of minimum ventilation inlets
Example of minimum ventilation inlets
Desired air flow pattern from minimum
ventilation inlet
Desired air flow pattern from minimum
ventilation inlet
96.2°F
95
90
85
80
75.0°F
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11/19/2009
Minimum ventilation inlet guidelines
Attic vs. outside temperatures
Draw air out of the attic
2)
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85.0°F
85
Less affected by wind
Warmer air for a portion of the day
80
90
85
75
80
75
70
70
erature (F)
Tempe
65
65
60
55
50
60.0°F
45
40
35
78.2°F
30
25
75
21-Feb
19-Feb
17-Feb
9-Feb
15-Feb
7-Feb
13-Feb
5-Feb
11-Feb
3-Feb
1-Feb
30-Jan
28-Jan
26-Jan
24-Jan
22-Jan
20-Jan
18-Jan
16-Jan
8-Jan
14-Jan
6-Jan
12-Jan
10-Jan
4-Jan
2-Jan
20
70
Date
65
attic
60
55
53.1°F
Minimum ventilation inlets above tube
heaters
Minimum ventilation inlet guidelines
3)
Located above a house’s heating system to help temper
incoming cold air
95.0°F
90
71.5
57.9
43.4
80
70
60
44.5
55.0°F
95.0°F
58.2
73.7
90
80
70
60.0°F
Minimum ventilation inlets above hot water
fin pipes
Minimum ventilation inlets above hot water
system
105.0°F
100
90
80
70
60
53.4°F
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11/19/2009
Generally, it is best to have a single row of
minimum ventilation inlets…
Minimum ventilation inlets
Heating system location have reduce problems with
minimum ventilation inlets near the side walls
Offset minimum ventilation inlets
Offset minimum ventilation inlets
Generally, it is best to have a single row of
minimum ventilation inlets…
Could be single direction inlets, but should be located near centerline
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11/19/2009
Two rows of bidirectional minimum
ventilation inlets
Two rows of bidirectional minimum
ventilation inlets
Beam deflecting air jet
105.0°F
105.0°F
100
100
90
90
80
80
70
70
60
60
55.0°F
55.0°F
A continuous inlet is a very poor
minimum ventilation inlet
Beam deflecting air jet
105.0°F
100
90
80
70
60
55.0°F
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11/19/2009
Very difficult to obtain a uniform small
opening…
Side wall or a ceiling continuous inlet
100.0°F
100
90
80
70
60.0°F
60.0
F
100.0°F
100
100.0°F
100
90
90
80
80
70
70
60.0°F
60.0°F
To maximize the tempering of the
incoming air…
Continuous inlets do not tend to produce
adequate tempering of incoming air
`
We must keep the air away from the birds as long as
possible
5C
10 C
Little tempering/mixing of incoming air
15 C
20 C
Air dumping to floor during minimum
ventilation..
103.5°F
100
95
90
85
80
78.3°F
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11/19/2009
Heating not being utilized on the far side of
the house.
Birds becoming chilled directly under inlet.
Fan side of house birds are significantly
warmer.
In order for a minimum ventilation inlet
system to work proper…
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All the air should enter through the inlets
If the houses are loose…
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Air entering through cracks will not mix.
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`
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Loose door
Drafts
Poor fresh air distribution
R d d litter
Reduced
l
d
drying
Loose door
37.8°C
37.8°C
35
35
30
30
105.0°F
25
25
100
21.1°C
21.1°C
90
37.8°C
35
80
30
70.0°F
25
21.1°C
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Loose door
Loose door
39.0°C
37.8°C
33.5
38
35
36
34
30
32
25
30
26.5
28
28.0°C
21.1°C
Loose door
Loose fan shutters
38.0°C
38
100.0°F
100
36
95
34
90
32
12.0
30
85
28
80
79.7°F
26
26.0°C
Loose fan covers
Loose side walls
72.1°F
105.0°F
70
100
53.4
90
60
80
50
56.4
70
60.6
40.0°F
65.0°F
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11/19/2009
Side wall leakage
Crack in side wall
105.0°F
100
90
80
70
60.0°F
0.3
0.28
0.26
0.24
0.2
0.22
0.18
0.16
0.14
0.1
0.12
0
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Turn on a two 36” fans (four 24” fans)
Measure the resulting static pressure
Then use the following chart to determine if the house is tight
enough
0.08
`
60
55
50
45
40
35
30
25
20
15
10
5
0
0.06
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Static pressure vs Opening
0.04
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We want all the air to enter through the inlets.
House tightness test should be conducted from time to
time.
0.02
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Leakagee Area (ft2)
Houses must be tight to maximize air
quality
Static Pressure
Optimally tight house
(0.65 square feet of leakage per 1,000 square feet of floor space)
Air inlet systems
1)
2)
Cold weather - minimum ventilation
Moderate weather – temperature control
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11/19/2009
Moderate weather inlets
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More needed than minimum ventilation inlets
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4 - 5 cfm per square foot of floor space
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Inlets on both sides of the house maximum
temperature and air quality uniformity
Around three times as much as minimum ventilation inlets
If not tunnel ventilated (7+ cfm/ft2)
Located along both side walls pulling air from directly
outside
t id the
th house
h
Attic inlets during for use for moderate
ventilation?
Attic inlets during hot weather
What makes a good temperature control
inlet?
Air flow directed toward ceiling at an angle
`
Directs the air where you want it to go.
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11/19/2009
Air flowing out of recessed inlet in 50’ wide
house
What makes a good temperature control
inlet
`
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Surface mounted inlet sits on the wall…
a recessed inlet sits in the wall.
Directs the air when you want it to go.
Recessed inlet
Cold air exiting sides of air inlet
Air flowing out side of inlet
Warm air flowing the side of recessed inlet
90.0°F
90
85
80
75
70.0°F
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11/19/2009
Air focused at top of the inlet which
improves throw
Examples of recessed side wall inlets
85.0°F
85
80
75
70
65
60.0°F
Moderate weather inlets
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More needed than minimum ventilation inlets
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4 - 5 cfm per square foot of floor space
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Air flow along the floor during warmer
weather
Around three times as much as minimum ventilation inlets
If not tunnel ventilated (7+ cfm/ft2)
Located along both side walls pulling air from directly
outside
t id the
th house
h
Ideally can direct the air up toward the ceiling during
cooler weather and down toward the floor during
warmer weather
Side wall inlet capable of directing incoming
air downward
Deflector board for hot weather bird cooling
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11/19/2009
Deflector board for hot weather bird cooling
Air inlets
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Cold weather – minimum ventilation
Moderate weather – temperature control
Hot weather – bird heat removal system
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Importance of air movement when it comes
to cooling birds
Hot weather is whenever it is warmer outside than you want it
inside.
In order to cool a bird we have to get air
to move over its body...
100.0°F
100
95
90
85
80
More air speed…
more cooling
Still Air - 25oC
75.0°F
300 ft/min - 25oC
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11/19/2009
Turkeys
0.75 m/sec - 26oC
(26oC – 150 ft/min)
39.0°C
38
36
34
32
30
28
26
26.0°C
2 m/sec - 26oC
2 m/sec - 26oC
39.0°C
38
36
34
32
30
28
26
26.0°C
Air movement in traditional cross-
Designed to conserve heat and not to
produce air movement over the birds
ventilation during hot weather
5C
10 C
15 C
20 C
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11/19/2009
Very little air movement at floor level during
cold weather
Designed to produce little air movement at bird level
5 m/sec
3.5 m/sec
2.5 m/sec
1.5 m/sec
less than 0.25 m/sec
During the summer they will tend to
conserve heat also…
Very little air movement during hot weather
as well
2.5 m/sec
26oC
26.5oC
1 m/sec
5 m/sec
27oC
28oC
0.75 m/sec to 0.5 m/sec over limited areas
Things are improved if you have inlets on
both sides of the house
2.5 m/sec
Attic inlets during hot weather
1 m/sec
5 m/sec
0.75 m/sec to .025 m/sec
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11/19/2009
Inlets in the center of the house
Side wall of house
Attic inlets during hot weather
Center of house
Inlets directed to the floor
Downward facing hot weather inlet improves
the situation even more
5 m/sec
2.5 m/sec
0. 5 m/sec
<0.25 m/sec
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11/19/2009
Downward facing inlets on both sides of th
house even better
Downward inlet on one side of a house
35.0°C
35
35.0°C
35
30
30
25
25
20
20.0°C
20
20.0°C
103.0°F
103.0°F
5 m/sec
100
100
95
95
90
90
85
85
1.5 m/sec
1 m/sec
80
80
75.0°F
75.0°F
Even with inlets that direct air
downward cooling fans may be required.
Using circulation fans for bird cooling
5 m/sec
1.5 m/sec
1 m/sec
36” circulation fan coverage area
15’
50’
50’
50’
Poor air movement distribution
50’
40’ wide house
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11/19/2009
36” circulation fans blowing across the
house
Limited coverage area
39.0°C
38
36
34
32
30
29.0°C
Most houses don’t have enough circulation
fans to provide the necessary air movement.
Birds directly in front of fan
39.0°C
38
36
34
32
30
29.0°C
Air inlets
`
`
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Best heat removal system is tunnel
ventilation
Cold weather – minimum ventilation
Moderate weather – temperature control
Hot weather – heat removal system
`
tunnel ventilation is just another inlet system
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11/19/2009
Air exchange and air velocity
Cross ventilation vs. Tunnel ventilation
100.0°F
100
95
Air velocity of between
2 and 3 m/sec
90
85
80
100.0°F
100
75.0°F
Air exchange typically less than every
60 seconds
95
90
85
80
75.0°F
Tunnel ventilation is just an additional
stage of ventilation
`
Minimum ventilation
For most of the year the house is no different from what
you may already be doing.
`
`
Fewer side wall/chimney fans
Fewer side wall inlets
+0.5 C
Moderate ventilation
+1.5 C
Moderate ventilation
+2 C
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11/19/2009
Low level tunnel ventilation
+3 C
High level tunnel ventilation
Medium level tunnel ventilation
+4 C
mczarick@uga.edu
(706) 540-9111
+4.5 C
www.poultryventilation.com
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