flow temperature of the boiler. Also press the “Summer” button until the green
light above this button is extinguished. Once a heating demand is received the fan
will start and the boiler will enter the pre-purge phase. During this phase the boiler
pump will also start to run. After 5 Seconds the boiler will start to spark and will
energise the gas valve. When ignition is achieved a dot will appear in the lower
right corner of the digital display to show the boiler is alight.
If an air lock or other blockage is present the unit may go to overheat or water
pressure lockout. This will be indicated by the display flashing error code “E03” or
“E37”. If this occurs clear the blockage and/or purge the air from the system, and
press the “Reset” button to restart the ignition sequence.
If ignition does not occur, the boiler, at approximately 20 second intervals, will
make four further attempts to light the burner.
If after five automatic attempts the boiler still fails to ignite, the display will show
the code “E 01” indicating no ignition.
If, after five manual attempts (to allow for purging of any air in the gas line), the
boiler still fails to ignite (indicated by the red (lockout) lamp) refer to Section 6.3 -
Fault Modes.
f.
Check for gas soundness between the gas service cock and connection to
the burner manifold.
5.6
HOT FLUSHING
a.
Allow the system to heat up, checking for water soundness.
b.
Follow instructions provided with the cleaning agent, i.e. Fernox Supafloc, or
equivalent. Turn off the boiler and flush the water system while still hot.
Thoroughly flush the system with clear water.
c.
Refill the system using a quality water treatment such as Fernox MB1 or Sentinel
X100. For sealed systems, fill to the required Initial Design Pressure.
5.7
COMBUSTION TESTING - MANDATORY CHECK
Competence to carry out the check of combustion performance
PLEASE NOTE: BS 6798:2009 Specification for installation and maintenance of gas fired
boilers of rated input not exceeding 70kW net advises that:
y
The person carrying out a combustion measurement should have been assessed as
competent in the use of a flue gas analyser and the interpretation of the results;
y
The flue gas analyser used should be one meeting the requirements of BS7927 or
BS-EN50379-3 and be calibrated in accordance with the analyser manufacturers’
requirements, and
y
Competence can be demonstrated by satisfactory completion of the CPA1 ACS
assessment which covers the use of electronic portable combustion gas analysers in
accordance with BS 7967, Parts 1 to 4.
Although the gas pressure is preset at the factory it is required to assure proper
combustion by measuring gas input and the level of carbon dioxide, or oxygen and carbon
monoxide, in the flue outlet from the boiler. Over firing or under firing the burner will
reduce the longevity of the appliance and may result in excessive carbon monoxide levels
Carbon dioxide and carbon monoxide are colourless, odourless gases produced by all
combustion processes. When the Keston condensing boiler is operating properly, carbon
dioxide (CO
2
) levels will be between 8.6 & 9% (low rate) and 9.1 & 9.5% (high rate) and
carbon oxide (CO) levels will be between 5 to 20 ppm (low rate) and 50 to 150 ppm (high
rate) for natural gas. For LP gas, carbon dioxide (CO
2
) levels will be between 9.6 & 10%
(low rate) and 10.4 & 10.8% (high rate) and the carbon monoxide will be between 5 & 20
ppm (low rate) and 50 & 150 ppm.
In any event, the CO
2
level at low rate must ALWAYS be less than CO
2
levels at high rate.
To measure CO
2
levels in the Keston boiler remove the 1/8" plug from the flue outlet pipe
spigot (Figure 6.7.4 item 7). Insert the probe of a calibrated combustion analysis meter
and sample the gases as instructed in the test equipment's instructions.
When firing the boiler for the first time since installation, the CO level at high rate may be
between 100-220 ppm and between 50-80 ppm at low rate. This is due to compounds
WD388/0/2004
Chapter 5 : Commissioning The Keston C36 Combi & C36P Combi Boilers
Installation & Servicing Instructions
Page : 25
