Bosch Buderus SSB255 Reference manual

Technical Service Bulletin:
Heat Exchanger: Refractory Replacement Procedure
Models: SSB255, SSB399, SSB512
Data subject to change without notice | Printed in the USA | BTC 438002102 B | 08.2019 Bosch Thermotechnology Corp.
WARNING:
The operations described here-below must be performed by
qualified personnel.
WARNING:
Before replacing the refractory, disconnect the equipment
from the power supply with the main ON/OFF switch and
close the manual gas shutoff valve.
CAUTION:
During every maintenance operation, always replace the
gaskets, especially the burner gaskets.
Replacement Procedure
Please follow the following steps for the refractory replacement:
1. Disconnect the two electrical connectors from the fan as shown in Fig.1
Figure 1
Electrical connectors
2. After closing the gas valve, disconnect the gas hose fitting as shown in
Fig.2.
Figure 2
Gas hose fitting
3. Disassemble the fan by unscrewing the 4 nuts that lock the flange to the burner
head as shown in Fig. 3.
Figure 3
4. Pull the fan upwards as shown in Fig. 4.
Figure 4
Fig. 2
Fan Flange

Data subject to change without notice | Printed in the USA | BTC 438002102 B | 08.2019 Bosch Thermotechnology Corp.
Technical Service Bulletin
2 | Heat Exchanger: Refractory Replacement Procedure
5. Remove the gaskets as shown in Fig.5 and Fig. 6 and pull up the burner as
shown in Fig. 7.
Figure 5
Figure 6
Figure 7
After removing the burner, continue as follows:
6. Unscrew the nuts that lock the burner flange as shown in Fig. 8.
Figure 8
7. Pull up the refractory ring, the flange sealing ring, and the steel basket as
shown in Fig. 9 and Fig. 10.
Figure 9
Refractory ring
Burner flange o-ring
Figure 10
Steel refractory holder
8. Access the refractory disk via the hole in the top of the combustion chamber
as shown in Fig. 11 and 12.
Figure 11

Data subject to change without notice | Printed in the USA | BTC 438002102 B | 08.2019 Bosch Thermotechnology Corp.
Technical Service Bulletin Heat Exchanger: Refractory Replacement Procedure | 3
Figure 12
Refractory disc
9. Pull the refractory disc out and carefully remove all of the debris from the
holder, as shown in Fig 13.
Figure 13
Place for dented
refractory disc
10. The replacement kit (part# 7738006357) contains 2 refractory half-discs,
a sealant cartridge and a fiber disc, shown in Fig. 14.
Figure 14
REFRACTORY
FIBER DISC
SEALANT
REFRACTORY
FIBER DISC
SEALANT
11. Place the fiber disc on the disc holder of the combustion chamber as shown
in Fig. 15.
Figure 15
12. Place the dented refractory half-disc (fig. 16) on the fiber disc;
Figure 16
13. Make sure the dented half disc is placed as shown in Fig. 17. Also make sure
it matches perfectly to the disc holder and to the coil by turning it with your
hand.
Figure 17

Data subject to change without notice | Printed in the USA | BTC 438002102 B | 08.2019 Bosch Thermotechnology Corp.
Technical Service Bulletin
4 | Heat Exchanger: Refractory Replacement Procedure
Bosch Thermotechnology Corp.
65 Grove Street
Watertown, MA 02472
Tel: [phone]
Fax: [phone]
www.boschheatingandcooling.com
14. Mark the steel coil at the two edges of the refractory half-disc as a reference
for the final assembly as shown in Fig. 18.
Figure 18
15. Remove the dented half-disk and place a strip of sealant on its inner edge as
shown in Fig.19.
Figure 19
16. Place the half-disk again on the disc holder by keeping the sealant upwards;
make sure the edges match with the marks previously taken as shown in
Fig. 20.
Figure 20
17. Take the second half-disk and place a strip of sealant at the inner edge as
shown in Fig. 21
Figure 21
18. Place the second half-disk matching the first one and press carefully by
hands without using any tools in order to avoid any possible breakage. See
Fig.22.
Figure 22
WARNING:
Please wait at least 12 hours before turning on the burner, or
you could risk damaging the heat exchanger.
19. Re-assemble all components, and check all gaskets (burner / o-ring flange
gaskets).