Technical information

27
NO
TE
: Vertical twin flue installations must have a trap on the
exhaust. MTS supply a suitable condense trap Part No.
705774 and recommend that this be used in the event that the
f
lue may form condense.
When siting the twin flue pipe, the air intake and exhaust
terminals must terminate on the same wall, the centres of the
terminals
must be a minimum of 280 mm apart and the air
intake
must not be sited above the exhaust terminal (refer to
Fig. 11.14). The air intake pipe can be run horizontally,
however, the terminal and the final 1 metre of flue must be
installed with a fall away from the boiler to avoid rain ingress.
I
t is also strongly recommended that the air intake pipe run be
constructed of insulated pipe to prevent condense forming on
the outside of the tube.
The maximum permissible flue length for twin flue is dependent
on the type of run used.
For flue runs with the intake and exhaust pipes under the same
atmospheric conditions (T
YPE 4) the maximum length is 34
metres (30kW), for runs with the terminals under different
atmospheric conditions (T
YPE 5) the exhaust terminal must
extend 0.5 metres above the ridge of the roof (this is not
obligatory if the exhaust and air intake pipes are located on the
same side of the building). For T
YPE 5 also, the maximum
permissible combined length is 56 metres (30kW).
The maximum length is reached by combining the total lengths
of both the air intake and exhaust pipes. Therefore a maximum
length of 56 metres for example, will allow a flue run of 28
metres for the air intake and 28 metres for the exhaust pipes,
also for each 90
o
elbow 1.3 metres must be subtracted from the
total length and for each 45
o
elbow 1 metre must be subtracted
from the total flue length.
Some of the acceptable flue configurations are detailed page
28.
For further information relating to flue runs not illustrated,
please contact the Technical Department on 0870 241 8180.
EXHAUST
AIR INTAKE
AIR INTAKE
AIR INTAKE MUST NOT BE
FITTED ABOVE THE EXHAUST
FIG.11.12
T
his procedure must be done as follows:
1 - Remove the air vent intake in the area indicated in
Fig. 11.13, by breaking the perforated ring.
2 -
Use a tool to grasp the lid and remove it completely.
3 - Clean any burrs or sharp edges with a knife or an
appropriate tool.
FIG. 11.13
FIG. 11.14
NOTE:
I
N
THE
EVENT THAT
280MM CENTRES
CANNOT
BE ACHEIVED
, IT
IS
PERMISSIABLE TO EXTEND THE EXHAUST PIPE
300MM FROM THE WALL