Principal Components Of The 42Bj; Fresh Air Controller; Filter And Access - Carrier 42BJ ULTRA Selection Manual

6 - PRINCIPAL COMPONENTS OF THE 42BJ

The basic module consists of a 3-speed centrifugal fan motor
with single wheel, forward-curved blade and single or double
inlet. Low noise was a key objective in the design of the fan
motor. In addition its high available static pressure allows the
ULTRA to be installed well away from the air conditioned space.
NOTE:
In order to simplify maintenance, the fan motor is held in
position by three lugs and one screw. Electrical connections
use a quick connector to prevent wiring errors and signifi-
cantly reduce maintenance time.

6.1 - Fresh air controller

The 42BJ ULTRA can be fitted with a constant fresh air flow
controller allowing the number of air changes to be controlled
accurately. It is vital to choose the correct constant fresh air
flow controller for the use to which the room or zone concer-
ned will be put.
The following range of controllers is available:
- 8.3 l/s or 30 m 3 /h (-10%; +20%)
- 16.6 l/s or 60 m 3 /h (-10%; +20%)
The fresh air supply is located upstream of the water coil. The
125 mm collar which houses the flow controller is made of
ABS.
16.7 l/s (60 m 3 /h) 20.8 l/s (75 m
27.8 l/s (100 m 3 /h) 36.1 l/s (130 m
The 16.6 l/s or 60 m 3 /h fresh air controller may be modified on
site by relocating or removing two plastic restricters in order to
increase its constant fresh air flow capacity to a maximum of
44.4 l/s or 160 m 3 /h.
A label on the 42BJ shows how to readjust the two plastic res-
tricters.
Fresh air controller
3 /h)
3 /h) 44.4 l/s (160 m 3 /h)
IMPORTANT:
If the ULTRA is fitted with a return air temperature sensor,
the constant fresh air flow rate must not exceed 50% of the
air flow rate delivered by the unit at minimum speed.
NOTE:
To operate correctly, the 8.3 l/s or 30 m
flow controller requires a differential pressure in the range
50 Pa to 200 Pa. The 16.6 l/s or 60 m
controller requires a differential pressure in the range 70 Pa
to 200 Pa.

6.2 - Filter and access

The 42BJ ULTRA is fitted with a high efficiency filter.
Fire rating medium M1, metal frame
Three filter access options are provided on the 42BJ:
- From above for units in false floor voids
- From below for units in false ceiling voids
- From the side for all applications
3 /h constant fresh air
3 /h constant fresh air
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