Bosch Singular 4000 Installation Instructions Manual page 61

I f there is no water supply valve, turn off the water supply at the water
main.
5. Remove the boiler front cover by loosening the 2 Phillips screws securing it
to the case.
Figure 95
6. Open the drain valve.
Figure 96
Singular Combi Boiler - BTC 439003301 B (2021/07)
7. Remove the strainer from the bottom of the boiler.
Figure 97
8. Close the drain valve when the water is completely drained.
9. Remove the cold water inlet fi lter.
10. Allow the residual water to drain from the boiler.
11. When the water is completely drained, reinsert the cold water inlet fi lter and
close the drain valve.
F ollow the steps in reverse order to refl l the boiler. Be careful not to lose
the drain plug.
Installation Instructions
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