Podab T 201 E Installation And Operation Manual - Requirements For Ventilation
7
©
PODAB 2012
Ventilation channel – choice of material
The ventilation channels shall be at least 100 mm in diameter
and should have a smooth inner wall.
We recommend that the ventilation system is built with rigid
metal ducts for best result. Flexible evacuating ducts for tumble
dryers can also be used.
NOTE: Never use flexible ducts through walls or other cov-
ered areas.
NOTE: Do not screw or nit the ventilation channel, so that
the screws will come through the inside of the pipe. This
construction will gather dust and impair the dryer’s perfor-
mance.
Requirements for incoming air
In order to make the dryer work properly, it is very important
that there is enough incoming air in the room. If the dryer is
installed according to this manual the air flow from the exhaust
will be about 150 m³/h. Incoming air must be at least equal to
the outgoing flow. We recommend the air flow to be greater
than the evacuated amount.
If the dryer is placed in a room where the incoming air flow is
insufficient, we recommend that you install an air exchanger.
Ventilation channel – design
IMPORTANT: Always make the channels as short as pos-
sible.
NOTE: If a tumble dryer is installed in an old ventilation
channel, please clean the channel properly.
In order for the dryer to work properly, the incoming air flow
must be sufficient. The amount of evacuated air per hour is
depending on how high the pressure fall in the ventilation chan-
nel is.
Material, the design and the length of the channel have a large
impact on the air flow. In order to get the best possible perfor-
mance, the pressure fall shall be as low as possible.
When the air is transported through the channel, it is exposed
to different kind of resistance. Factors that give a low pressure
fall:
•
Smooth inner walls on the pipe
• Large diameter on the pipe
• Short length on the pipe
• Few curves
• Few angels (90 degrees)
Evacuated amount of air and pressure
fall
In order to get the cabinet to work properly, the ventilation
channel shall be designed to get an outcoming air flow from
the dryer of at least 150 m³/h. In order to get this air flow, the
pressure fall must not exceed 50 Pa. By an air flow of 150 m³/h
and a diameter of the pipe of 100 mm, this corresponds to a
straight, smooth ventilation channel of 13 m.
Pressure fall estimation
The counter pressure in the ventilation channel can be mea-
sured with a pressure meter. The measuring point shall be
placed by the evacuating outlet of the dryer.
In order to estimate the pressure fall without meter equipment
we recommend the following:
•
Identify the ventilation channel’s incoming components in the
air flow direction.
•
Check the part pressure fall for each component in the table.
•
Calculate the total amount of pressure fall by adding each
parts pressure fall.
The table shows the most common components in a ventilation
system. The information shall be considered as approximate
data. For more information, contact the manufacturer of the
parts of the system.
NOTE: The data is for an air flow of 150 m³/h.
Component
Pressure fall
Circular channel
ø, mm
Pa/m
r
Ø
Ø
100
4
125
1,3
Pipe bends 90°
ø, mm
Bend radius,
mm
Pa/bend
r
Ø
Ø
100
100
6,5
125
125
3
Reduction
Transition, mm
Pa/reduction
r
Ø
Ø
100 till 125
4,2
125 till 100
4,5
Example: 9 m long 100 mm channel with 2 pipe curves which gives an estimated
pressure fall of (9 x 4) + (2 x 6,5) = 49 Pa.
NOTE: If the highest allowed level of air pressure is exceed-
ed an external fan could be needed. Otherwise the drying
result is effected negatively. T 201 E is prepared for an ex-
ternal fan. Contact your local dealer or PODAB for more
information.