Cleaning The Heat Exchanger - Worcester GREENSTAR 24i Junior Installation, Commissioning And Servicing Instructions

SERVICE AND SPARES
MAX
1
2.5 mm
MIN
2
4 mm
Fig. 83 Gas valve adjustment
CO/CO settings for Greenstar i Junior
2
CO/CO should be measured after 10 minutes.
2
Gas type CO max.
2
9.8% ± 0.5
Natural gas
11.0% ± 0.5
L.P.G.
NOTE: When checking an existing appliance the tolerance is ± 0.5.
If checking after cleaning or component replacement or for adjustment
when the reading obtained is outside the tolerances given above, then
the tolerance is ± 0.2.
CO - less than 200 ppm (0.002 ratio)
Table 18 CO/CO settings
2
6.7

CLEANING THE HEAT EXCHANGER

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.
NOTICE: CO/CO CHECKS
2
▶ If the joint between the Air/Gas manifold and heat
exchanger is disturbed the sealing gasket must be
replaced.
▶ After completing the service of the appliance, the CO/
CO must be checked and set to the limits shown in
2
"Setting the air/gas ratio" on page 37.
There is a special accessory kit available specifically
designed for cleaning the heat exchanger. If required
order 7 716 192 312.
▶ Isolate the power to the appliance and remove outer case and base
panel.
1. Refer to figure 84 and remove the clip from gas valve outlet.
If the plastic elbow can not be easily removed, undo the
nut to push the plastic elbow out of the fitting.
2. Pull the gas outlet elbow free from the gas valve.
38
Fig. 84 Gas valve connection
6720643895-66.1Wo
▶ Remove electrical connector and earth wire from fan.
CO min.
2
8.8% ± 0.5
▶ Disconnect spark electrode and flame sensor connections.
10.5% ± 0.5
1. Refer to figure 85 and undo the securing nut on the top of the heat
exchanger and remove the retaining plate assembly.
Fig. 85 Securing nut
1. Refer to figure 86 and rotate fan and air/gas manifold assembly
around the top of the heat exchanger until it stops at the lug.
2. Remove the cover panel by removing retaining screw.
▶ Lift up assembly and remove from boiler.
Fig. 86 Rotate air/gas manifold
2.
To prevent damage to the electrodes when removing the
air/gas manifold, disconnect the leads to the electrodes.
1.
1.
6720804530-16.1Wo
1.
6720643895-72.1Wo
2.
6 720 802 047 (2013/05)