42
15.5
To replace domestic heat
exchanger
A
F
B
C
E
G
D
H
-
Drain down heating circuit of boiler as
described previously.
-
Drain down hot water circuit of boiler as
follows:
-
From below boiler, close cold water inlet
isolating valve.
-
Open a hot tap to drain hot water cir-
cuit.
-
Remove clip (A) and pull off microswitch
assembly
-
Undo connections (B), (C), (D) and (F)
on 3 way valve
-
Grasp 3 way valve and lift upwards
releasing ‘O’ ring joint (E)
-
Remove 3 way valve and domestic heat
exchanger assembly (G) from boiler.
Important: Take care not to drip water
into PCB housing when removing
assembly.
-
Fit replacement heat exchanger (G) in
reverse order to removal.
-
Open isolating valves on fl ow and return
connections, refi ll, vent and pressurise
boiler. Check for leaks.
-
Open cold water isolating valve. Check
for leaks.
15.6 To
replace
thermistor
-
Locate thermistor clipped onto fl ow pipe
behind and to the right of the pump.
-
Pull off clip from fl ow pipe.
-
Remove electrical connections from
thermistor.
-
Fit replacement thermistor in reverse
order to removal.
Note:
1) No heat sink compound is
required.
2) The polarity of the connections
is not important.
15.7
To replace overheat thermostat
-
Locate overheat thermostat on left hand
side of main heat exchanger at rear.
-
Remove electrical connections from
overheat thermostat.
-
Unscrew and remove two screws
securing overheat thermostat to heat
exchanger.
-
Fit replacement overheat thermostat in
reverse order to removal.
Note:
1) No heat sink compound is
required.
2) The polarity of the connections
is not important.