Lifebreath Clean Air Furnace CAF-02-MB - Manual (Page 18)

This is an example for determining the airflow in a 6" duct.
The Pitot tube reading was 0.025inches of water. From the
chart, this is 640 feet per minute.
The 6" (15.2 cm) duct has a cross sectional area of:
= [3.14 x (6"ч12) 2 ]ч4
= 0.2 square feet
The airflow is then:
640 ft./min. x 0.2 square feet = 128 cfm
For your convenience, the cross sectional area of some
common round duct is listed below:
DUCT DIAM. (inches) CROSS SECTION AREA (sq. ft.)
5.0 (125 mm) .14
6.0 (150 mm) .20
7.0 (175 mm) .27
The accuracy of the airflow reading will be affected by how
close to any elbows or bends the readings are taken.
Accuracy can be increased by taking an average of multiple
readings as outlined in the literature supplied with the Pitot
tube.
18
BUILT-IN
BALANCING
DAMPERS
BACK DRAFT
DAMPER
OUTSIDE
INSULATED PIPE
WITH VAPOUR
BARRIER
Figure C
Push and turn with slotted
screwdriver. Damper
automatically locks when
pressure is released.
When connecting ductwork
to the collar, take note where
screws are located. Screws
should be located no further
than 1/2” (12.70 mm) from out-
side edge of collar, so as not to
impede operation of the damper.
1/2” (12 mm)
Insulated flexible
ducting
Balancing Collar Instructions
Figure D
Pitot Tube Air Flow Balancing
A Backdraft Damper is required in the exhaust
air duct to prevent cold air from entering the
unit when the Clean Air Furnace is not running.
WARNING
Back Draft Damper
The back draft damper (not included) can be located any-
where in a vertical rise of the exhaust duct.