Calculation of exhaust ducting

Exhaust connections

A pipe diameter of 5" should ensure trouble-free extraction up to a total pipe length of 5.4. meters (17 1/2 ft).

Determine the total pipe length as fol- lows:

Measure the total length of ducting needed.

Add the length of additional ducting to this figure according to the num- ber and type of bends (see table below).

Example

Wall vent (1)	1.1 m	43’’
Flexible
90° bend (2)	0.3 m	12’’

Note

If the exhaust ducting will run through rooms, ceiling space etc. where there may be variations in temperature the problem of sweating or condensation will have to be addressed.

The exhaust ducting may need to be in- sulated.

Flexible pipe (3)	1.0 m	39’’
Flexible
45° bend (4)	0.2 m	8’’

Total pipe length	2.6 m	81/2’’

With a total pipe length of 81/2 ft. (102’’) the exhaust is within the effec- tive range.

Air flow rates:

- Setting 1 240 m3/h (145 CFM)

- Setting 2 465 m3/h (275 CFM)

Type of bend	Angle	Radius of	Radius of	Effective	Effective
	of bend	bend	bend	pipe length	pipe length
		(in mm)	(in inches)	(in meters)	(in inches)

Flexible pipe	45°	120	4 3/4	0.2	8’’
	90°	120	4 3/4	0.3	12’’

Wall vent				1.0	39’’