Buderus GB142 Reference manual

Technical service bulletin
Heat Exchanger Replacement
Bulletin Number: TBG-35 | Model: GB142 series boilers
Data subject to change without notice | BTC 435002107 B | 02.2021
Heat Exchanger Replacement Procedure
Remove the cable plug from the gas control valve.
Figure 1
Remove both cable plugs [Fig.2, pos.1] from the fan unit.
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Figure 2
Pull down on both retaining clips [Fig.3, pos.1] to open and
remove the burner cover.
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Figure 3
Remove the burner [Fig.4, pos.1].
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Figure 4
Disconnect the supply [Fig.5, pos.1] and return [Fig.5, pos.2]
sensors.
CAUTION: electrical short circuit
To prevent mix-ups, the supply sensor is marked by a
red sleeve on the side of the cable harness.
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Figure 5
Disconnect the safety sensor [Fig.6, pos.1].
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Figure 6
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Bulletin Number: TBG-35 | GB142 Heat Exchanger Replacement Technical service bulletin
Data subject to change without notice | BTC 435002107 A | 05.2012
Disconnect the hot surface ignitor and ionization electrode
plugs.
Loosen the fastening screws [Fig.7, pos.1].
Pull the ground cable from the hot surface ignitor [Fig.7,
pos.2].
Dismantle the mounting plate [Fig.7, pos.3].
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Figure 7
Remove both the hot surface ignitor and the ionization
electrode from heat exchanger [Fig.8].
Figure 8
Open latches [Fig.9, pos.1] on the condensate collector.
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Figure 9
Remove the condensate collector.
Dismantle the tension spring [Fig.10, pos.1] between the
supply pipe and the heat exchanger.
Fully loosen nut [Fig.10, pos.2]. Remove both the nut and the
clip that was revealed beneath it from the old heat exchanger
and reinstall them on to the replacement heat exchanger in
the same location.

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Figure 10
Loosen with one turn the nut [Fig.11, pos.1] between the
supply
Pull the supply pipe [Fig.11, pos.2] out of the heat exchanger.
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Figure 11
Pull the combustion air supply and flue gas exhaust
connections on top of the appliance upwards to remove
them.
Loosen all fastening screws of the flue gas adapter.
Remove the flue gas adapter [Fig.12, pos.1] from the top of
the appliance.
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Figure 12
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Bulletin Number: TBG-35 | GB142 Heat Exchanger Replacement Technical service bulletin
Data subject to change without notice | BTC 435002107 B | 02.2021
Bosch Thermotechnology Corp.
65 Grove Street
Watertown, MA 02472
Tel: [phone]
Fax: [phone]
www.bosch-thermotechnology.us
Remove the heat exchanger by pulling forward on the bottom
end and then pushing it upwards [Fig.13].
Figure 13
Remove the flue gas collector from the old heat exchanger,
including the oval seal.
Put silicon on both sides of the new oval seal [Fig.14, pos.2], the
flue gas collector and the new heat exchanger [Fig.14, pos.1].
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Figure 14
Reassemble the flue gas collector with the new oval seal to the
new heat exchanger.
Check if the new oval seal is placed correctly by opening the
condensate collector.
Install the new seal for the condensate collector [Fig.15, pos.2].
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Figure 15
Install the new heat exchanger and all other parts in reverse
order of disassembly.
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