Detailed recommendations for the flue installations are given in BS 5440:1:2000. The following
notes are for general guidance only.
Note: An adapter is always required on top of the heater.
For the vertical flue set up, offset adapter will be supplied for the air intake.
a) The flue system must be constructed using only Powermax approved components.
b) It is important that the position of the terminal allows free passage of air across it at all times.
c) It is ESSENTIAL TO ENSURE that products of combustion discharging from the terminal
cannot reenter the building, or any other adjacent building, through ventilators, windows, doors,
other sources of natural air infiltration, or forced ventilation / air conditioning.
d) The minimum acceptable dimensions from the flue terminal to obstructions and ventilation
openings are specified in Figs. 4& 5 opposite.
e) If the flue terminal discharges into a pathway or passageway check that combustion products
will not cause nuisance and that the terminal will not obstruct the passageway.
Assembling Air/Flue Pipes
The flue pipes must be assembled with the plain end of pipe or fitting nearest the boiler and the
female (socket) end furthest from the boiler. Check that a seal is fitted in every socket.
Always adjust length of pipes by cutting and de-burring plain end so that it does not damage or
disturb the seal. Remove burrs from inside and outside of pipe and ensure the pipe is clean and
free from oil and grease.
Any generally "horizontal" run of the flue pipe MUST NOT FORM A LOW POINT at which
condensate could accumulate.
a. Measure and cut the first pair of the flue pipes away from the appliance. Push pipes fully into
the sockets on top of the boiler whilst also fitting the flue duct prepared as above.
b. Measure and cut next pair of the air/flue pipes.
c. Prepare pipe support brackets as required before engaging pipes with the socket of preced-
ing pipes or bends.
d. Push pipes together as before taking care not to dislodge seals. When cutting and fitting the
flue pipes on extended the flue systems, allow approx. 5 mm clearance at the bottom of each
joint - see Fig. 8.
e. Repeat above procedure to reach terminal. Ensure that air inlet and the flue gas connections
are correctly made and are not inadvertently reversed.
f. Fix pipe supports to masonry or woodwork so that the flue/air pipes are held securely in
g. Check especially that all joints within any duct or other void are correctly engaged and sealed
before fixing the ductwork.
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