Combi 70 & Combi 90 Oil Boilers
42
1 Follow steps 1 to 4 of section 9.2.
2 Unscrew and disconnect pipe unions 1, 5 & 9. See
Fig. 38 or 39. Remove the vertical 15 mm pipe
from the boiler.
3 Unscrew and remove all eight screws from the
diaphragm housing. Unscrew union nut 7 and carefully
remove the front of the diaphragm housing.
4 Remove the large spring and then the complete
push rod/diaphragm assembly from the valve
housing, carefully pulling on the push rod to
disengage it if necessary .
5 Refit the diaphragm and re-assemble the diverter
valve using the reverse of the above procedure.
Ensure that the beaded edge of the diaphragm is
correctly seated into the corresponding groove in the
diverter valve body, and that the spring is fitted,
before replacing the diaphragm housing and screws.
6 Open the cold water inlet valve (A). Refill the
central heating system as described in section 5.2,
checking for leaks.
7 Open a hot tap and check that the diverter valve is
activated and operates both microswitches.
1 Unhook the expansion vessel from the front of the
boiler and lay to one side.
2 Close the cold water inlet isolating valve (A). Refer
to Fig. 38 or 39.
3 Unscrew and disconnect pipe unions 1, 5 & 9. See
Fig. 38 or 39. Remove the vertical 15 mm pipe from
the boiler.
4 Unscrew the two other unions 11 and 12 on the
mixing valve, and remove valve from the boiler.
5 Dismantling of the main body of the valve for
inspection and/or cleaning should be carried out as
follows:
a) Remove the control knob fixing screw.
b) Pull off the control knob and carefully lever off
the plastic housing under the knob, having
noted the correct positions.
c) Unscrew the brass top assembly from valve body.
d) Remove the lower assembly and spring.
e) Carefully remove any scale deposits or other
particles from the valve seat and other
components. Vinegar can be used to remove
calcium, but take care not to scratch metallic
surfaces. Do not use any other solvents.
f) Re-assemble the valve using reverse of the above
procedure, ensuring that the large diameter of the
spring is at the bottom of the valve.
6 Replace the mixing valve using the reverse of the
above procedure.
Important: Ensure that the mixing valve is
correctly connected, i.e. with the Hot (H) inlet at
the rear and the Cold (C) inlet at the front.
7 Set the control knob to setting 4, i.e. the 4 on the
knob lines up with the white index mark on the
valve. Check temperature calibration, and adjust if
necessary (see paragraph 8).
8 Re-calibration of the valve, after dismantling,
should be carried out as follows:
a) Set the boiler On/Off switch to On and allow
the hot water store to reach temperature, i.e.
wait until the burner stops. Open a hot tap and
draw off hot water at a medium flow of about
10-12 litres per minute.
b) Adjust the control knob to give an outlet water
temperature of 40°C, measured using a
thermometer in the flow from the tap.
c) Close the hot tap. Without disturbing the valve
position, remove the knob fixing screw and pull
off the control knob.
d) Replace the control knob such that the number
2 lines up with the white index mark.
e) Refit and tighten the knob fixing screw. Reset
the control knob to setting 4.
f) Once correctly set, the control knob can be
locked in position to prevent tampering by
tightening the small grub screw in the side of
the knob using an Allen key.
1 Drain the central heating system and boiler using
the drain cock on the boiler.
2 Unscrew the flexible hose union nut on the
expansion vessel and disconnect the hose.
Note: Ensure the sealing washer inside the union is
kept for re-assembly.
3 Slacken the two cross head screws and remove the
mounting bracket from the expansion vessel.
4 Fit the bracket onto the replacement vessel and
tighten both screws evenly.
9 - REPLACEMENT OF BOILER COMPONENTS
Diverter valve diaphragm
9.3
Thermostatic mixing valve
9.4
Expansion vessel
9.5
To Next Page
Loading...
