Navien NCB300-28K, Service Manual

Page: 103 / 108

102 Inspection and Maintenance Schedule
8.5.3 CO and Combustion Checks
IMPORTANT PRELIMINARY INFORMATION ON CHECKS
Note
The air gas ratio valve is factory set and must not
be adjusted during commissioning unless this
action is recommended following contact with the
manufacturer.
●
If any such adjustment is recommended and further checking
of the boiler is required the installer/service engineer must
be competent to carry out this work and to use the flue gas
analyser accordingly.
●
If the boiler requires conversion to operate with a different
gas family (e.g. conversion from natural gas to LPG) separate
guidance will be provided by the boiler manufacturer.
●
The boiler manufacturer’s installation instructions should have
been followed, gas type verified and gas supply pressure/rate
checked as required prior to commissioning.
●
As part of the installation process,
especially where a flue
has been fitted by persons other than the boiler installer
,
visually check the integrity of the whole flue system to
confirm that all components are correctly assembled, fixed
and supported. Check that manufacturer’s max. flue lengths
have not been exceeded and all guidance has been followed
(e.g. Gas Safe Technical Bulletin TB008 where chimney/flues
are in voids).
●
The Flue Gas Analyser should be of the correct type, as
specified by BS 7967. Prior to its use, the flue gas analyser
should have been maintained and calibrated as specified
by the manufacturer. The installer must have the relevant
competence for use of the analyser.
●
Check and zero the analyser in fresh air as per analyser
manufacturer’s instructions.
- CO
: carbon monoxide,
CO₂
: carbon dioxide,
O₂
: oxygen,
ppm
: parts per million
-
Combustion ratio : The CO reading measured in ppm
divided by the CO₂ reading first converted to ppm
-
GU(I&U)R : Gas Safety (Installation and Use) Regulations