Bosch Therm C950ES Technical Service Bulletin page 2

18 | Replacing & Servicing the Condensing Heat Exchanger - C950ES, C1050ES
Inspecting condensing heat exchanger
Note: If removing the lower copper heat exchanger, refer to
Technical Service Bulletin: Replacing the Heat Exchanger now. If
installing a new condensing heat exchanger, skip the next
section.
1. Using a fl ashlight, look through the rear inlet slot of the heat
exchanger so that the fi n coils inside are visible.
2. If there are any signs of soot, combustion byproducts or
corrosion, the condensing exchanger must be disassembled to
clean the fi n coils.
Disassembling condensing heat exchanger
1. Remove clips from copper "U" bend pipe (Fig. 2, pos. 5) and
"offset" pipe (Fig. 2, pos. 6). Remove pipes from heat exchanger.
2. Remove the four 4mm hex head screws from one side of the heat
exchanger. (Fig. 3, pos. 1)
3. Carefully separate one side of heat exchanger from main body by
prying evenly. Use caution to prevent damage to the aluminum
and gasket.
4 Please note o-ring positions when dissassembling. Smaller
o-rings (Fig. 3, pos. 2) fi t on fi n coil pipe ends. Larger o-rings are
placed on the outside of the heat exchanger sides
(Fig. 3, pos. 3).
5. Gently pull both fi n coil tubes (Fig. 3, pos. 4) free from the
exchanger body. If necessary, the other side of the heat
exchanger can be removed to ease removal of fi n coils.
6. With fi n coils exposed, vacuum them clean with a soft bristle
vacuum brush. Then spray clean with water. Ensure drain hole
in bottom right of exchanger is clear of debris or corrosion.
Reassembling and installing condensing heat exchanger
1. Reinsert fi n coils (without o-rings) into exchanger body. (Fig. 3,
pos. 4).
Data subject to change without notice | Printed in the USA | BTC 740002314 B | 06.2011
Figure 2
5 5
2. Place side with gasket (Fig. 3, pos. 5) on to main exchanger body
and push fi rmly on sides to properly seat fi ncoils.
3. Install four 4mm hex head screws with washers to secure each
heat exchanger side (Fig. 3, pos. 1)
4. Place four small o-rings (Fig. 3, pos. 2) on fi n coil ends and four
large o-rings (Fig. 3, pos. 3) where "U" bend, "offset", and cold
water pipes connect. Use dish washing liquid to lubricate large
o-rings and seat them with connecting pipes.
5. Reinstall "U" bend pipe on right side of exchanger (Fig. 2, pos.
5) and "offset" pipe on to left side rear of heat exchanger (Fig.2,
pos. 6). Secure both pipe connections with clips.
6. If lower heat exchanger was removed, reinstall before
proceeding.
7. Place condensing heat exchanger back into heater. Ensure that
gaskets between upper and lower heat exchanger and between
condensing exchanger and fl ue gas collector are correctly in
place.
8. Tighten the four 8mm nuts at the bottom front and top rear of
condensing exchanger. (Fig. 2, pos. 4). Note: two left nuts are
not visible in Figure 2.
9. Install the two Phillips screws and two 4mm hex head screws
from the top left and right of the exchanger (Fig. 2, pos. 3).
10. Reinstall upper cold water pipe (Fig. 2, pos. 2) and connecting
pipe (Fig. 2, pos 1) with o-rings to left side of exchanger. Secure
with clips.
11. Reinstall condensate drain pipe to connector with o-ring and
clip. (Fig. 1, pos.3).
12. Reinstall exhaust temperature sensor with washer and screw
(Fig. 1, pos. 1).
13. Reconnect wire leads to overheat sensor/ECO (Fig. 1, pos. 2).
14. Turn on water supply and check for leaks.
15. Replace combustion and front covers.
16. Plug in power cord and return heater to service.
Technical Service Bulletin
Figure 3
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: 1-800-283-3787
Fax: 1-603-584-1687
www.bosch-climate.us
Bosch Thermotechnology Corp.