It's not uncommon for installers or repairers to omit a fairly costly item
like inhibitor. Without any, a system will still last the warranty period.
And then provide more work for them or their trade rather earlier than if
it is used. A win win situation - for them.

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*Why do the two "sanction"s (noun and verb) mean opposites?*

Dave Plowman London SW
To e-mail, change noise into sound.