28
8.5
Flue Terminal
Never use aluminum containing flue gas materials for this boiler range
The flue terminal duct can be made of:
•
Stainless steel in combination with
T120
gaskets.
•
PP temperature class
T120.
8.5.1
V
ERTICAL
F
LUE
T
ERMINAL
P
OSITIONING
Please refer to the relevant British Standards:
•
BS 6644
– Installation of gas fired hot water boilers of rated inputs between 70kW – 1.8MW.
Please refer to the Instition of Gas Engineers and Manager Documents (IGEM):
•
IGEM/UP/10 Edition 4
– Installation of gas fired hot water boilers of rated inputs between 70kW – 20MW.
8.5.2
C
OMMON
F
LUE
/
D
UCTS
Multiple boilers can be connected to a common duct. These flue gas systems for multiple boiler installations must
always be engineered as zero or negative pressure systems; this to prevent the risk of recirculation of the flue gases.
In circumstances where a zero or negative pressure cannot be achieved, please call Strebel Ltd Technical
Department for advice.
8.6
Air supply
If an air supply duct is connected from outside the building to the boiler, the boiler will operate as a room-independent
boiler (closed boiler).
The supply duct can be made of:
•
PVC
•
Thin-walled aluminium
•
Stainless steel
The air supplied for the boiler room ventilation shall be such that the maximum temperatures within the boiler house
shall be:
•
25
o
C at floor level (or 100mm above floor level);
•
32
o
C at mid-level (1.5m above floor level); and
•
40
o
C at ceiling level (or 100mm below ceiling level).
8.6.1
A
IR QUALITY
Combustion air must be free of contaminants. For example: chlorine, ammonia and/or alkali agents, dust, sand and
pollen. Notice that installing a boiler near a swimming pool, a washing machine, laundry or chemical plants does
expose combustion air to these contaminants.
If the combustion air is taken from the boiler room, the inlet air must be clean and free of water. Always use a wire
mesh to prevent debris being drawn into the air inlet
8.6.2
A
IR SUPPLY THROUGH HUMID AREAS
When the supply duct is installed in a boiler room with humid air (for example: greenhouses), a double wall
supply duct or an insulated duct should be considered to prevent condensation on the outside of the duct.
It is not possible to insulate the internal air pipes of the boiler. Make sure that no condensate can be formed
on the internal air canals.
The air supply duct must be protected against rain, when it is installed on top of the roof.
