Nancy -- it depends on the manufacturer of the blower/fan. Some manufacturers do, some don't. If it's not marked, never take the word of the supplier but look up the model number with the original manufacturer.
As far as your question about duct work sizing - are you asking if it is ok to (for example) run 8" to the fan, then after the fan run 10"? The quick and dirty answer is yes. You can always INCREASE the size of the ducting in the direction of the airflow, but you should never DECREASE the size of the ducting in the direction of the air flow. (caps for emphasis).
Quote:
Originally Posted by Just Nancy
Not to hijack but I have a question.
Do fans usually say on them how many cfm's the move? I've seen some that do but my exhaust had other information but not that.
I was just curious.
Oh, and is it ok for the duct work to be smaller and get bigger at the fan? I thought I'd seen that before. Again, mostly curious.
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