Bosch C1210ESC Technical Service Bulletin page 2

18 | Descaling the Heat Exchanger
14. Run solution through the heater until the solution returning to
the descaling reservoir/bucket comes out clear. Changing to a
fresh solution may be necessary during this process.
15. Properly discard of dirty descaling solution. Disconnect lines A
and C (Fig. 1). Reconnect cold water supply to the water heater.
16. Open cold supply shutoff valve to fl ush water heater with clean
water. Allow enough water to fl ow through the heater to
properly fl ush it. Filling the 5 gallon descaling bucket once
should be suffi cient.
17. Close cold water shutoff valve and disconnect line B (Fig. 1).
Reconnect hot water line to the water heater.
18. Plug in power cord and press On/Off button to "On".
19. Open water shutoff valves, and return water heater to service.
Water Quality
Water quality can have an impact on appliance longevity and may

void the manufacturer's warranty.
For water analysis data, call your local water department. If on a

well, have the well water analyzed periodically. If water quality
exceeds one or more of the values specifi ed in Figure 2, Bosch
recommends consulting a local plumber about installing a water
conditioner or softener.
If the tankless water heater is operating in applications where

the outlet temperature exceeds 140°F, a water softening system
is strongly recommended. The higher the set temperature is on
the appliance, the greater the risk for scale/mineral deposits.
Damage from scale/mineral deposits is not covered under
warranty. Refer to manufacturer's limited warranty.
Data subject to change without notice | Printed in the USA | BTC 740002309 B | 06.2011
Description
pH
TDS (total Dissolved
Solids)
Total hardness
Aluminum
Chlorides
Copper
Iron
Manganese
Zinc
Technical Service Bulletin
Figure 2
Max. Levels
pH 6.5 - 8.5
mg/l or ppm 500
100
gpg or ppm
(6 gpg)
mg/l or ppm 2.0
mg/l or ppm 250
mg/l or ppm 1.0
mg/l or ppm 0.3
mg/l or ppm 0.05
mg/l or ppm 5.0
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.