Haier AB242ACBEA Service Manual page 51

The length difference among every duct is limited below 2:1.
Reduce the length of duct as possible as can.
Reduce the amount of bend as possible as can.
Use heat insulation material to bind and seal the part connecting main unit and the flare part of air
discharging duct. Perform duct installation work, before the fitment of ceiling.
Bad example
7. Calculation method of the dimension of the simple quadrate air duct
Presuming the unit length friction impedance of the duct is 1Pa/m, when the dimension of one side of
the air duct is fixed as 250mm, as shown below:
B
A
The calculation of duct resistance (the simple calculation is as follow table)
Straight part
Bend part
Air out part
Static pressure box
Air inlet grille (with air filter)
The chosen chart of simple duct
Note:1Pa/m=0.1mmAg/m
Shape
Item
Air volume
3 3
m /h(m /n)
100
200
300
400
500
600(10)
800
1,000
1,200(20)
1,400
1,600
Bad example
Air conditioner
A
A
Static pressure box Equipped with
air filter (bought)
Calculate as per 1m length 1Pa, 1Pa/m
Each bend takes as a3~4m long straight duct
Calculate as 25Pa
Calculate as 50Pa/each
Calculate as 40Pa/each
Square duct
Dimension
(mmxmm)
250 x 60
250 x 90
250 x 120
250 x 140
250 x 170
250 x 190
250 x 230
250 x 270
250 x 310
250 x 350
250 x 390
Good example
Air volume
2400m 3 /h
A
3
(40m /min)
600m 3 /h
B
3
(10m /min)
Shape
Square duct
Item
Dimension
Air volume
3 3
(mmxmm)
m /h(m /n)
250 x
1,800(30)
250 x
2000
250 x
2400
250 x
3,000(50)
250 x
3,500
250 x
4,000
250 x 920
4,500
250 x 1000
5,000
250 x 1090
5,500
250 x 1180
6,000(100)
430
470
560
650
740
830