Keston C45 Installation And Servicing Instructions page 29

WD536 Chapter 4 : Commissioning
e. Adjust the upper rotary control knob, central heating temperature, to the
maximum clockwise position. Adjust the lower rotary control know, DHW
temperature, to the maximum clockwise position.
Once a demand is received the left hand digit of the boiler display will change to
"1" to indicate the boiler has entered the 10 second pre-purge phase. During this
phase the boiler fan and pump will start to run. The digit will then change to "2" to
indicate ignition is taking place whilst the gas valve is opened and the spark
generated. Once the gas has ignited at the main burner the left hand digit will
change to "3" or "4" (depending on demand received) 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 first digit of the display showing "9"
and a flashing error code starting with "b". 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 02" 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 5.3 -
Fault Modes.
f. Check for gas soundness between the gas service cock and connection to
the burner manifold.
4.6 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.
4.7 COMBUSTION TESTING
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:
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;
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
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 ) levels will be between 8 & 8.2% (C45 low rate), 8.3 & 8.5% (C55 low rate),
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8.2 & 8.7% (C45 high rate) and 8.6 & 9% C55 (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
(C55P low rate), 9.8 & 10.3% (C40P high rate) and 10 & 10.5% (C55P high rate) and the
carbon monoxide will be between 5 & 20 ppm (low rate) and 50 & 150 ppm.
In any event, the CO
Installation & Servicing Instructions
) levels will be between 9.3 & 9.5% (C40P low rate), 9.6 & 9.8%
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level at low rate must ALWAYS be less than CO
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The Keston C45, C40P, C55 & C55P
levels at high rate.
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