Atmos Energy HE26 - Manual (Page 32)

5.8 Atmos Communal Flue System (CFS)
A design service is provided for each application. There are different
configurations possible and the main ones are illustrated.
CFS-NV Naturally ventilated, working under negative pressure
CFS-FA Fan assisted, working under positive pressure – smaller
diameter pipes are used
5.8.1 Atmos CFS EO – FA System
Appliance category: C83 (Communal Flue System, Exhaust (Flue) Only –
Fan Assisted)
An air supply from the outside wall and a roof outlet with common
discharge system is allowed. The system is fan assisted positive pressure.
A non-return valve arrangement on each boiler is essential to
prevent recirculation of exhaust gases to non operational
appliances. There is a common condensate collector at the base of the
flue system which must be taken to a suitable drain.
Maximum pipe length
The maximum length of the air supply and flue discharge pipes
between appliance and common flue discharge and air supply
together is 75 metres (80mm pipes).
Common flue discharge
The outlet of the flue discharge can be made at any place in the pitching
roof surface, provided that the outlet in the roof surface has the same
orientation as the air supply in the outside wall. With a flat roof the outlet
of the flue discharge must be made in the 'free' outlet area.
5.8.2 Atmos CFS System
Appliance category: C43
CFS – NV or CFS – FA systems are available. The fan assisted positive
pressure system allows a more compact installation. Connection from the
appliance can be either twin pipe or concentric. There is a common
condensate collector at the base of the flue system which must be taken
to a suitable drain.
CFS – FA systems require a non-return valve arrangement on each
boiler, which is essential to prevent recirculation of exhaust gases to
non operational appliances.
CAUTION
For the common flue discharge cover and air supply cover
a certificate of incorporation from the Gastec-Gasinstituut
is required.
Maximum pipe length
The maximum length of the air supply and flue discharge pipes
between appliance and CFS system together is 75 metres (80mm
pipes).
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