18
12.5 Fitting the twin pipe (Ø80/80)
Where it is not possible to terminate the flue within the distance permitted for coaxial flues, the twin flue pipe can be used by
fitting a special adaptor to the flue connector and using the aperture for the air intake located on top of the combustion
chamber.
Considerations necessary for twin flue installation;
It is most important to avoid any possible condense formation entering the appliance.
Condense may form when the 24kW boiler has an exhaust pipe longer than 5.5m and on the 30kW when the exhaust pipe is
longer than 7.5m. If this is the case, there are two options;
1)Where condense will form but can be negated with insulated flue, install the insulated flue ensuring it has a fall of 5mm in
every metre away from the boiler.
2)The exhaust flue will have a fall of 3
o
back to the boiler and a suitable trap will be fitted on the exhaust as close to the boiler
as possible, condense will then be suitably disposed of.
Where the flue runs through cold spots, i.e. loft areas, condense is likely to be formed, therefore in such cases a fall back to
the boiler and a trap is required.
Always ensure that the flue is adequately supported, avoiding low points. (MTS supply suitable clamps as Part No. 705778).
To utilise the air intake it is necessary to:
1) Take the air intake cover off
2) Assemble the flange on the header supplied with the boiler
3) Insert the restrictor if necessary, on the tube or the elbow
4) Insert the header on the tube or the elbow up until the lower stop
(you do not have to use the washer).
5) Insert the elbow/header in the boiler air intake hole and fasten it with screws
The twin flue pipes can be fitted with or without additional elbows and need no clamps, simply ensure that the red o-ring is
inserted in the female end of the flue pipe and push the extension piece fully into the previous section of flue pipe or elbow,
check that the o-ring is not dislodged when assembling the flue.
Twin pipe can also be converted back to Coaxial flue to enable vertical termination with a coaxial kit by using the pipe bridge
(Twin - Coaxial Adaptor - Part No. 705767). When running the twin flue pipe vertically, a condense trap must always be used
on the exhaust pipe.
It is not recommended that the pipe bridge for horizontal termination, however in the unlikely event that this proves to be a
necessity it is extremely important that the entire flue has a fall of 3
o
back to the boiler, is suitably trapped and where the
12
Connecting the Flue (continued)
If the two elbows are to be
run in the same lateral
direction and if you need to
reduce the required space
above the boiler, the
minimum 230 mm
measurement can be
reduced by carefully cutting
the elbow below the air inlet
by 25 mm
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