Ariston Clas 24 FF Installation And Servicing Instructions page 18

installation
IMPORTANT!!!
Where condense will form within the fl ue system, ensure there is
a fall back to the boiler of 3oand a suitable trap is fi tted as close
to the boiler as possible. MTS supply a suitable collector Part No.
3318026.
Fig. 24
18
Note: Vertical twin fl ue installations must have a trap on the
exhaust. MTS supply a suitable condense trap Part No. 3318026
and recommend that this be used in the event that the fl ue may
form condense.
When siting the twin fl ue 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. 27). The air intake
pipe can be run horizontally, however, the terminal and the fi nal 1
metre of fl ue must be installed with a fall away from the boiler to
avoid rain ingress.
It 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 fl ue length for twin fl ue is dependent
on the type of installation.
For fl ue runs with the intake and exhaust pipes under the same
atmospheric conditions (Type 4) the maximum length is 44 metres
(31kW), for runs with the terminals under diff erent atmospheric
conditions (Type 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 Type 5 also, the maximum permissible combined length is 40
metres.
Fig. 23
The maximum length is reached by combining the total lengths
of both the air intake and exhaust pipes. Therefore a maximum
length of 40 metres for example, will allow a fl ue run of 20 metres
for the air intake and 20 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
fl ue length.
Some of the acceptable fl ue confi gurations are detailed on page
19 (Fig. 26).
For further information relating to fl ue runs not illustrated, please
contact the Technical Department on 0870 241 8180.
Fig. 25
120
o elbow 1 metre must be subtracted from the total
180