14
5 - FresH aIr
5.1 - constant fresh air controller (optional)
The constant fresh air controller for the 4GM gives
precise control of the rate at which fresh air ventilation air
is introduced and the supply air refresh rate. Selection of
the fresh air controller bearing in mind the occupancy of
each room or zone is critical.
Range of fresh air flow controllers available:
•
8.3 l/s (30 m
3
/h): -10%; + 0%
•
16.6 l/s (60 m
3
/h): -10%; + 0%
The fresh air supply is located before the filter and the
water coil.
The collar which houses the flow controller is made of
recyclable ABS and has a connection diameter of 15 mm.
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 4GM front fastening support shows how to
readjust the two plastic restricters.
NOTE: To operate correctly, the 8.3 l/s or 30 m
3
/h constant
fresh air flow controller requires a differential pressure in
the range 50 Pa to 200 Pa. The 16.6 l/s or 60 m
3
/h constant
fresh air controller requires a differential pressure in the
range 70 Pa to 200 Pa.
16.6 l/s (60 m
3
/h)
20.8 l/s (75 m
3
/h)
27.7 l/s (100 m
3
/h)
36.1 l/s (130 m
3
/h)
44.4 l/s (160 m
3
/h)
Modification procedure:
•
Disconnect the fresh air duct from the plastic spigot
on the 4GM.
•
Move or relocate the two plastic restricters.
•
Reconnect the fresh air duct to the spigot.
5.2 - Variable fresh air controller (optional)
The 4GM can be equipped with a variable fresh air con-
troller that permits control of the air introduction and
renewal. The fresh air rate can be set at the Carrier controller.
This fresh air controller is supplied by Carrier and can be
installed directly on the front fastening support of the
4GM unit, which is designed to accommodate it.
NOTE: Carrier recommends the installation of a straight
semi-rigid circular duct (12.5 mm diameter) 180 mm long
(1.5 x diameter) upstream of the controller. This must be
as straight as possible to prevent any problems in the pipe
(maximum pipe run without bends).
The variable fresh air controller, supplied by Carrier,
requires a static pressure that is higher than the 180 Pa
minimum.
Accessory fresh air duct
Flexible fresh air duct, diameter 15 mm, maximum length
500 mm, fire rating M1, fitted with a coupling sleeve at
each end.
