Lennox FLEXY FX 025 Application Manual page 9

GENERAL DESCRIPTION
INDOOR AIR QUALITY AND ENVIRONMENT
FRIENDLY
STANDARD FEATURES
Quiet FLEXY FX
LENNOX believes that an innovating and environment friendly
rooftop should be quiet. Even without the Low Noise option, the
FLEXY FX is a reference on the market for standard low level of
noise.
INDOOR AIR QUALITY DOES MATTER
Fire proof (M0) insulation
Because, for LENNOX, health and safety issues cannot be com-
promised, in all rooftops fi re insulation (M0 fi re Class) is fi tted as
standard. 65 kg/m insulation is mechanically fi tted to the unit.
3
This feature improves the safety of the rooftop against fi re, as the
specifi cation suggests, the insulation will not burn and smoke will
not be generated.
Edges of insulation are protected to perfectly seal the Rockwool.
Drain Pan
The underside of the unit is insulated to prevent from condensation.
The bent drain traps are shipped in a kit form. Drain pan is sloped
to prevent stagnation of water.
It slides out and can be easily cleaned, preventing growth of
bacteria in the drain pan.
Application Guide • FLEXY FX-AGU-1112-E
Accurate percentage of fresh air (under patent)
Because a fresh air damper curve is not linear, it is not accurate
to assume that the percentage of opening of the damper is equal
to the percentage of fresh air entering the building.
However, this linear control of a damper is by far the most used
in the industry.
With Indoor air quality and running cost of a building being more
important to our customer, Lennox wanted to pilot the % of fresh
air more accurately.
The CLIMATIC 50 can now periodically recalibrate the dampers,
by calculating the real percentage of fresh air entering the building
for the each different positions of the damper.
This recalibration is achieved using the return air sensor, the
outdoor sensor and supply air sensor. When all heating or cooling
elements are off, the percentage of fresh air actually entering the
rooftop is the result of the following equation :
"%Fresh Air" =
"Supply Air temperature" - "Return Air Temperature"
"Fresh air Temperature " - "Return Air Temperature"
For example, CLIMATIC 50 would accurately adjust the damper
position to get 20% fresh air and not 30% or 10%.
Therefore, this feature either saves a lot of energy cost by not
bringing more fresh air than needed or makes sure that air quality
is at the expected level.
This allows CLIMATIC 50 to send an alarm when damper can not
be calibrated (faulty damper)
Specifi c case of high pressure drop in the return air duct:
The problem becomes even more critical, when the return air duct
pressure drop is greater than 50 Pa.
In this case, due to the diffi culty of the return air to go back to the
rooftop, it is usual to have a lot more fresh air entering the building
than wanted, resulting in high running cost.
OPTIONAL
Indoor Air Quality Sensor
Indoor air quality is controlled from the CLIMATIC 50 boards. A
VOC (Volatile Organic Component) sensor will detect the amount
of CO2 in the air between 0 and 2000PPM. (This obviously varies
depending upon space occupancy levels). The VOC sensor will
then send a proportional signal (0-20mA) to the CLIMATIC 50
controller which will then modulate the fresh air damper.
Double skin 25 mm :
To prevent bacteria development on porous surface Lennox pro-
vides double skin panels option. This double skin panels give a
smooth inside the unit and allow an easy cleaning of the panel.
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