You are confusing conditional and temporal clauses. 'If' suggests as possible situation (the possibility may be real, hypothetical or counterfactual); 'when', or any other time word presents the situation as factual.
If John retires next year, he will move to Rome. The speaker thinks it is possible that John will retire. His moving to Rome is conditional on that retirement.
When John retires next year, he will move to Rome. The speaker accepts as a fact that John will retire. His moving to Rome is also seen as a (future) fact. There is no condition here.
Please bear with me a moment longer, because I would really like to get to the bottom of this once and for all.
Am I to conclude that once "if" is replaced with "when" in a conditional sentence, this sentence ceases to be a conditional sentence full stop/no exceptions?
I guess when I saw these examples:
Examples of real conditional sentences expressing habitual activities:
If he eats breakfast, he feels better all day.
If he eats breakfast, he will feel better all day.
If he ate breakfast, he felt better all day.These generalizations can also be expressed by using when or whenever instead of if:
When water boils, it turns to steam.
When he eats breakfast, he feels better all day.
When he ate breakfast, he felt better all day.
at this page http://faculty.deanza.edu/flemingjohn/stories/storyReader$18 I gathered that all of them were also conditional sentences and incorrectly incorporated temporal clauses into the family of conditional clauses.