Flue System And Air Supply; Air Supply; Conventional Flue Systems - Grant Vortex Pro Internal Combi Series Installation And Servicing Instructions

9

fLUE SYStEM anD aiR SUppLY

9.1

aiR SUppLY

A sufficient permanent air supply to the boiler should be provided
for the following reasons:
• For proper combustion of fuel and effective discharge of
combustion products to the open air.
• For the ventilation of any confined space in which the boiler
is installed to prevent overheating of the boiler and any
equipment in and near the boiler.
It should be both the designer's and installer's concern that the air
required for these functions be introduced so as to cause as little
discomfort as possible to the building occupants and thus to offer
them the least temptation to obstruct the ventilators.
Further details may be obtained from BS 5410-1.
! nOtE !
For a boiler fitted in a compartment, which is ventilated as
shown, no additional allowance is necessary.
Open flue - Extract fans, where needed, should be in accordance
with Section 5.4.7 in BS 5410-1.
All ventilation areas given are for domestic applications and relate
to the full output rating of the boiler.
For installations in older dwellings (constructed prior to the
introduction of Approved Document L1A 2006) the first 5 kW of
output can be ignored. For all other cases refer to BS 5410-2.
BOILER IN
ROOM
Room sealed balanced flue
no ventilation required to room
BOILER IN
B
COMP AR TMENT
B
Room sealed balanced flue
compartment ventilated from room
figure 9-1: Air supply for room sealed balanced flue boilers
table 9-3: Ventilation areas
Output Combi XS 26
area cm²
Vent A 143
Vent B 286
Vent C 143
Vent D 286
Vent E 429
Section 9: flue System and air Supply
A
A
Room sealed balanced flue
compartment ventilated from outside
Combi 21
in² cm²
22 116
44 231
22 116
44 231
67 347
BOILER IN
C
ROOM
Conventional open flue
BOILER IN
C
D
COMP AR TMENT
E
Conventional open flue
compartment ventilated from room
figure 9-2: Air supply for conventional flue boilers
9.2

COnVEntiOnaL fLUE SYStEMS

! nOtE !
Under no circumstances can Grant Vortex boilers be
installed with existing flue systems. Only flue systems and
components suitable for wet flues should be used.
Failure to install the correct type of flue system will
invalidate the guarantee.
Grant condensing boilers have high operating efficiencies and
low flue gas temperatures. Care must be taken to ensure the
flue system is suitable for the very low flue gas temperatures and
condensate in the flue gases.
Suitable conventional flue systems are available from Grant UK.
The flue must terminate in a down draught free area, i.e. at least
600 mm above the point of exit through the roof or preferably
above the ridge level.
The condensate may be allowed to run back into the boiler. A
condensate drain at the base of the flue system is not required.
The high level flue terminal must be at least 600 mm from
any opening into the building, and 600 mm above any vertical
structure or wall less than a horizontal distance of 750 mm from
the terminal.
Combi 26
in² cm²
18 143
36 286
18 143
36 286
54 429
C
D
Conventional open flue
compartment ventilated from outside
Combi 36
in² cm²
22 198
44 396
22 198
44 396
67 594
in²
31
61
31
61
92
page 27