Ferroli F24 Installation, Servicing And User Instructions Manual page 16

3.04 Top Outlet: Two Pipe Flue System
3.04.1 Two pipe connection
Two separate ducts Ø80 for air intake and flue gas discharge can
be directly connected to the boiler. For converson to top outlet
(see 3.05) mount the separate outlet kit
Connect flue duct to central hole Ø80 and air duct to left or right air intake hole Ø80. Insert blanking
plate 2 in remaining air intake.
A varied number of accessories for two pipe systems are available from Ferroli (ref. to page 17). Before
installing your system please check via calculation table at 3.08.2 you are not exceeding the maximum
permissible length for the appliance.
Notes on two pipe system installation:
When using the two pipe system the flue discharge pipe must have a 25mm air gap when passing through
combustible materials.
Where the flue discharge pipe passes through the airing space of an airing cupboard it must be protected by a non
combustible guard or expanded metal giving an annular air gap of at least 25mm.
Where the flue discharge pipe passes through a wall containing cavity insulation, a non combustible sleeve must
be fitted. Additionally a gap of 25mm between the sleeve and the insulation should be provided by cutting back
the insulation or packing loose fill bead insulation with mineral fibre.
Where the flue pipe is run through an unheated roof space it should be insulated with non combustible insulating
material to prevent condensation. The flue pipe should be supported at intervals of not more than 1.8m and
the support should be preferably below a joint.
3.04.2 Two pipe fl ue system
• Calculating maximum permissible fl ue length.
The calculation method is based on a standard reference parameter (1 metre of horizontal air flue 80 diameter 80) for
the maximum length permissible for all the pipes + fittings flow resistance coefficient. In other words, for all components
and pipes in the different installation configurations (vertical or horizontal, air or flue, etc.) and for all the fittings, a
flow resistance (reduction) equivalent to x metre of horizontal air induction pipe is indicated. For every boiler
model a maximum pipe length is provided, expressed in n metres of horizontal air pipe. In this way, to calculate
the length of a proposed 2 pipe air-flue system, add the flow resistance (reduction) in equivalent metres-air. For
every component and fitting present in the system, and to check that the total is less than the maximum length
the permissible for the boiler model.
IMPORTANT: the pipes and fi ttings fl ow resistance (reduction) have been summarised on the following pages.
The fl ow resistance values written refer only to Ferroli pipes and fi ttings.
Calculation routine
Utilise the pipes and fittings flows resistance tables on the following pages and calculate the total flow
1.
resistance in metres-air, by adding the flow resistances of the components in the whole air-flue system, based
on their position (vertical or horizontal, air inlet or flue outlet).
Please note that the same fitting, identified by a one code (i.e. 1 pipe diameter 80, code KWMA83A), can offer
different flow resistances if positioned as air inlet or flue outlet, if placed vertically or horizontally.
The fl ow resistance of the special two pipe fl ue-air adapters do not have to be included in the calculation
as they are already included in the maximum length calculation.
For the restrictors, please refer to cap. 3.02 to determinate the correct diaphragm.
2.
Check that the total flow resistance calculated is less or equal to 48 metre, the maximum permissible
3.
for Ferroli F24.
16
1
Insert blanking plate 2
in remaining air intake
Fig. 19
Ferroli F24
Ø80
FLUE
2
Ø80
AIR
1