andrews CWH30/100 Installation Manual, Operation And Maintenance Manual page 39

MAINTENANCE SECTION 7
The burner and exchanger do not normally need to be cleaned. If there is a suspicion of
dirt then the exchanger should be opened on the bottom. New gaskets must always be
used when assembling. The top of the exchanger must never be opened.
The hot surface igniter is a vulnerable part that should only be removed if it has to be
replaced.
Only original parts recommended by the manufacturer can be used as replacement parts.
Components that are sealed may not be changed or dismantled.
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