Servicing The Compact Thermal Module - Vaillant ecoMAX 646 Installation And Maintenance Manual

7 Inspection and maintenance
Always perform the following steps prior to maintenance
work:
• Switch off the mains switch.
• Disconnect the appliance from the mains supply by de-
energising the appliance by means of a separator with
a contact opening of at least 3-mm (e.-g. fuses or cir-
cuit breakers).
• Close the gas shut-off valve.
• Close the heating supply and return and the cold
water inlet valve.
• Take the front casing off the appliance.
Always perform the following steps after performing any
maintenance work:
• Open the heating supply and return and the cold water
inlet valve.
• Refill the appliance, if necessary, on the hot water side
up to a pressure of between 1.0 and 2.0 bar and bleed
the heating system (see chapter 5.1).
• Open the gas shut-off cock.
• Reconnect the device to the mains supply and switch
on the mains switch.
• Check the appliance for gas and water leaks.
• If necessary, refill and re-bleed the heating system.
• Put on the appliance's front casing.
7.2.1

Servicing the compact thermal module

Dismantling the compact thermal module
The compact thermal module consists of a speed-con-
trolled fan, combined gas/air fittings, the gas supply
(mixer tube) for the fan of the pre-mixing burner and the
pre-mixing burner itself. These four components make
up the complete assembly that is the compact thermal
module. Proceed as follows to dismount it: (see fig. 7.1)
Danger!
There is danger of being injured or scalded at
the compact thermal module and at all compo-
nents carrying water. Only work on the compo-
nents once they have cooled down.
The mixer tube (7) between gas control unit and
burner may not be opened. It can only be guar-
anteed that this component is gas-tight after it
has been inspected at the factory.
• Cut off the gas supply to the appliance.
• Lower the switch cabinet.
• Undo the fastening screw of the air intake
pipe (5) and lift the air intake pipe forward (3); remove
the air intake pipe from the intake socket.
• Pull the two plugs of the ignition und grounding lines
off the ignition electrode (6).
• Undo the gas supply line (10) on the underside of the
gas fitting (fig. 7.2).
• Pull the cables (9) off the fan motor and the cable (8)
off the gas fitting.
• Undo the five nuts (2).
26
Caution!
Under no circumstances may the compact ther-
mal module be suspended from the flexible cor-
rugated gas pipe.
• Pull the entire compact thermal module (4) off the in-
tegral condensation heat exchanger (1).
1
2
3
4
5
6
7
8
9
Fig. 7.1 Dismounting/Mounting the compact thermal module
Mounting the compact thermal module
Danger!
The two silicon seals (1) on the compact ther-
mal module (fig. 7.3) (SP no. 98-1046) must be
replaced every time maintenance is carried out.
The burner flange insulation (2) on the compact
thermal module (fig. 7.3) (SP no. 21-0734) must
not show any signs of damage; if it does, it
must also be replaced.
• Put the compact thermal module (4) onto the integral
condensation heat exchanger (1) (fig. 7.1).
• Tighten the five nuts (2) evenly and crosswise.
• Put the air intake pipe (3) onto the intake socket and
tighten the screw (5).
• Connect the gas supply line (10) with a new seal (SP
no. 98-0012) to the gas fitting (fig. 7.3). Use the span-
ner flat at the flexible gas line to hold the gas fitting.
• Connect the two plugs of the ignition und grounding
lines to the ignition electrode (6).
• Connect the cables (9) to the fan motor and the cable
(8) to the gas fitting.
• Open the gas supply to the appliance.
Installation and maintenance manual ecoMAX 646
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