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5.6
Construction of the concentric tubes
When installing a concentric system its proper functioning is determined by the resistance
of the concentric tubes. Avoid horizontal installation of the tubes. These create the most
resistance.
The total horizontal length of the system should never exceed the total vertical
length!
The figures below are ranked from the least to the most efficient.
◼
In Figure A, one goes vertically upward from the appliance until the height of the
flue gas exhaust is reached. There a bend of 90° is installed and then a horizontal
tube to the outside
◼
In Figure B, one goes vertically upward to a certain extent, after which one moves
gradually via 15° bends to a horizontal tube that leads to the outside
◼
In Figure C, one immediately exits the appliance via a bend of 45°. Near the outer
wall a second bend of 45° is installed to reach the exit horizontally. This method
produces the least possible resistance and is therefore the most appropriate.
Ensure that with long flue lengths the concentric tubes are secured every two
metres so the weight of these does not rest on the appliance.
Start constructing the concentric system from the appliance.
All elements of the air supply and the gas flue must have at least 25 mm of
overlap when fitted together and be fastened with clamps or stainless steel Parker
screws so they do not slide apart.
A
Good
B
Better
C
Best