Fresh Air Damper - Free Cooling - Lennox CLIMATIC series User Manual

COMPONENTS
FRESH AIR DAMPER
Function
Ensure a minimum fresh air introduction into the room and/or a free-cooling, free-heating, thus reducing electric consumption.
Description
Fresh air setting
Adjustement by setpoint
The fresh air rate is adjustable by set point for each schedule mode (Night, Day, Day I, Day II BMS)
2823 → Minimum opening of the fresh air damper, %, adjustment by zone.
9h
It is also possible to set a second threshold for minimum fresh air opening in case of very low outside air temperature
(3828) Activation of second minimum opening fresh air threshold
(3829) Second minimum fresh air damper opening, %, adjustment by zone.
(3832) Outside air temperature set point to activate the second threshold
It is also possible to set a maximum fresh air thresholdin set point (3822).
Adjustement by free contacts (Optional)
With the customized free contacts, the fresh air rate can be adjusted (See Customized Input / Output (BE.60))
• Contact closed on [No F.A], the unit will close completely the fresh air damper.
• Contact closed on [All F.A], the unit will open completely the fresh air damper.
• Contact closed on [x% F.A.], the unit will open the damper to x%.
If several contacts customized with this functionality are closed, the fresh air damper will open according to the sum value of all
closed contacts. In any case, the minimum fresh air rate will be fi xed according to the highest value between the set point and
the free contacts request.
Adjustement by external signal (Optional)
The minimum fresh air can be remotely modifi ed by a 4-20mA signal (See Customized Input / Output (BE.60))
For a 4mA signal of, the threshold is set to 0%, for a 20mA signal, it is set to 100%, a linear rule is applied in between.
Fresh air damper calibration
The real fresh air volume introduced into the system is not always proportional to the damper opening percentage, particularly
when the return air duct system is sized to give excessive pressure losses.
This may result with excessive fresh air input, and thus with an increase of the system exploitation costs.
In the menu (3825), it is possible to enable the fresh air calibration which is then performed by measuring temperature of blowing
air, return air and outside air.
The CLIMATIC calculates and stores the exact percentage of fresh air for each damper position.
This sequence takes place periodically when all heating and cooling elements are off.
• 20 •
12h/0h
Day mode
35%
Night mode
3h
15%
DayI mode
20%
6h
24h/12h
Night mode
15%
Day mode
21h 35%
Night mode
DayI mode
15%
20%
18h
CLIMATIC RT_UNITARY-IOM-1508-E
15h