Flue Gas Analysis; Cleaning The Heat Exchanger - Worcester 27i System Compact Installation, Commissioning And Servicing Instructions

SERVICE AND SPARES
6.6

FLUE GAS ANALYSIS

NOTICE: Combustion testing
▶ Combustion testing must be carried out by a
competent person. Testing must not be attempted
unless the person carrying out the combustion check
is equipped with a Combustion Analyser conforming
to BS 7927 and is competent in its use.
Ensure that the gas inlet pressure has been checked and
is satisfactory, refer to section 5.5.1.
COMBUSTION TEST
If the optional integral diverter valve is fitted (not
supplied) and the Service mode and maximum output
are selected the boiler will operate both the Central
Heating and DHW circuits with the diverter valve in the
mid position. This is to allow sufficient time for the
setting procedure.
When the water temperature reaches 75°C the diverter
valve will switch to CH only.
For S and Y plan systems only use the Central Heating
circuit.
▶ Connect the flue gas analyser to the flue gas sampling point (1) as
shown in the figure below.
▶ Ensure that the probe reaches the centre of the flue gas exhaust,
adjust the cone on the probe so that it seals the sample point and
correctly positions the end of the probe.
▶ Press the and buttons together
eco
– The chimney sweep symbol will be displayed at the top of the
screen.
– "Max" will flash at the bottom of the screen.
– The boiler will ramp up to maximum output in approximately 30 to
35 seconds.
▶ Run the boiler at maximum output for at least 10 minutes.
▶ Check the CO/CO readings against the information in table 14.
2
1
Fig. 75 Combustion test
▶ Check CO is less than 200ppm.
▶ Set the boiler to minimum power by pressing the down arrow button.
– "Min" will flash at the bottom left of the screen.
40
– The boiler will take 30 to 35 seconds to ramp down to minimum
output.
– Allow the boiler to stabilise at minimum output for at least 10
minutes.
▶ Check the CO/CO readings against the information in table 14.
2
▶ Check that the CO is less than 200ppm.
▶ Return the boiler to maximum, by pressing the UP arrow button, and
re-check the CO/CO .
2
– "Max" will flash at the bottom left of the screen.
– The boiler will take approximately 30 to 35 seconds to ramp up to
maximum output.
– Allow the boiler to stabilise at maximum output for at least 10
minutes.
▶ If correct, press the button and the boiler will return to normal
operation.
▶ Re-assemble and refit boiler case.
Note: Natural Gas and L.P.G. minimum CO
tolerance of plus 0.5% to minus 1.0%
CO/CO settings for Greenstar i System
2
CO/CO should be measured after 10 minutes.
2
Gas type
27i System Natural gas
L.P.G.
30i System Natural gas
L.P.G.
CO - less than 200 ppm (0.002 ratio)
Table 14 CO/CO settings
2
If the boiler fails the combustion test, check:
1. Air intake for restriction
2. Cleanliness of the heat cell, condition of the burner, plus blockages in
the condensate disposal.
6.7

CLEANING THE HEAT EXCHANGER

NOTICE: Gaskets
▶ Replace the burner and electrode assembly gaskets
after cleaning the heat exchanger.
There is an optional tool available to assist in cleaning the
heat exchanger, part number 7 746 901 479
The following items will have to be removed to gain access to the heat
exchanger for cleaning:
▶ Lower the control panel into the service position.
▶ Remove the case.
▶ Disconnect electrical wires to the fan, ignition transformer, spark
electrodes, flue overheat thermostat, main heat exchanger
temperature sensor and flow pipe temperature sensor.
▶ Flueway
▶ Fan assembly
▶ Ignition transformer
▶ Spark electrode assembly
▶ Burner housing, burner and gasket
Refer to sections 6.8.9 to 6.8.13 for instructions on how to remove the
items to gain access to the heat exchanger channels so that the heat
exchanger can be cleaned
Greenstar i System Compact - 6 720 807 726 (2013/05)
has a
2
CO max. CO min.
2 2
9.1% ± 0.5
8.5% + 0.5/ - 1.0
10.6% ± 0.5 9.6% + 0.5/ - 1.0
9.1% ± 0.5
8.5% + 0.5/ - 1.0
10.6% ± 0.5 9.6% + 0.5/ - 1.0