Installation Instructions

Regulations and operating conditions
6 720 645 817 (2010/09)
44
6.4 Combustion air
Where combustion air is concerned, ensure that it is not
heavily contaminated with dust and contains no
halogenated compounds. Otherwise there would be a
risk of damage to the combustion chamber and the
secondary heating surfaces. Halogenated compounds
are highly corrosive. These can be contained in spray
cans, thinners, cleaning & degreasing agents and
solvents. Design the combustion air supply so that, for
example, no extract air is drawn in from chemical
cleaners or paint shops. Special requirements apply to
the supply of combustion air in the installation room.
The Suprapur gas condensing boiler is prepared for
balanced flue operation. Balanced flue operation is
possible via the connection set. This is also appropriate,
for example, if the combustion air could be
contaminated.
Routing flue gas in chimney shafts with secondary
ventilation
No cleaning is required if the flue gas is routed through
a chimney shaft with secondary ventilation (Æ Fig. 48 on
page 80).
Routing air and flue gas in countercurrent
Clean the chimney shaft as follows if the combustion air
supply is drawn through the shaft in a countercurrent
(Æ Fig. 52 on page 88):
If dust loads due to fragile chimney pointing are to be
expected, also clean and seal the chimney shaft.
6.5 Combustion air supply
The conditions of installation rooms and the siting of gas
appliances must comply with country-specific
regulations.
For open flue combustion equipment with a total rated
output in excess of 50 kW, the combustion air supply is
deemed to be ensured if an aperture to the outside with
a clear opening of at least 150 cm
2
(plus 2 cm
2
for every
kilowatt output above 50 kW rated output) is provided.
The required cross-section may be split over up to two
lines and must be sized to provide the equivalent air flow
rate.
General requirements
• Combustion air vents and lines must never be closed
or covered if appropriate safety equipment cannot
ensure that the combustion equipment can only
operate when the flow cross-section is free.
• The required cross-section must not be restricted by
a closure or grille.
• An adequate supply of combustion air can also be
verified by other means.
Previous use of the
chimney shaft/
chimney
Required cleaning
Ventilation shaft Thorough mechanical
cleaning
Routing flue gas from
gas combustion
Thorough mechanical
cleaning
Routing flue gas from
oil or solid fuel
Thorough mechanical
cleaning; sealing the surface
to prevent vapour from
residues (e.g. sulphur) in the
brickwork permeating the
combustion air
Tab. 24
To avoid having to seal the chimney shaft:
Choose open flue operation or draw in
combustion air via a coaxial pipe inside the
chimney shaft or a separate pipe from
outside.