39
Minimiser
-
Installation
75 HEAT EXCHANGER REPLACEMENT
SERVICING
IMPORTANT.
Before starting the removal procedure, protect the gas and
electrical controls with a waterproof sheet or plastic bag.
Refer also to Frame 10 - 'Boiler exploded view'.
1.
Refer to Frame 58.
2.
Drain down the system.
3.
Drain the heat exchanger via the drain point,
taking care to protect electrical components
from water.
4.
Remove the fan assembly - refer to Frame
53.
5.
Remove the burner assembly - refer to
Frame 65.
6.
Remove the gas injection pipe - refer to
Frame 67.
7.
Remove the spark generator - refer to Frame
64.
8.
Remove the back retaining screw.
9.
Withdraw the dry fire thermostat phial from
its pocket - refer to Frame 61.
10.
Remove the condensate siphon - refer to
Frame 74.
11
. Disconnect the flue gas sampling tube from
the top of the heat exchanger.
12.
Remove the flue thermostat - refer to Frame
62.
13
. Disconnect the boiler flow and return pipes
from the system pipework close to the boiler.
SER
VICING
Flow pipe
Return pipe
16
Bosses
Flow
14
Support
Boiler
Heat exchanger
12
11
14
. Remove the control thermostat phial from its pocket - refer to
Frame 59.
15.
Disconnect the overheat 'stat electrical leads.
16.
Undo the flow and return pipe union nuts and pull the pipes clear
of the flow and return bosses.
17.
Undo the four flow and return boss retaining screws.
18.
While supporting the heat exchanger from below, withdraw the
bosses from the flow and return tappings.
If necessary, the bosses may be 'jacked' out by screwing the
retaining screws into the two threaded holes in each flange.
Check the O rings for damage and replace if necessary.
19.
Lower the heat exchanger to disengage from the flue connector
tube, and withdraw it from the boiler.
20
. Fit the new heat exchanger and re-assemble in reverse order.
IMPORTANT
The flow and return bosses are not common and MUST be refitted in
their correct positions.
The FLOW connection boss has a COARSE thread.
The RETURN connection boss has a FINE thread.
8
3
Return
18
17
15
