General

[quote=Urpleness]A one hour nap because the beginning of "one" isn't pronounced with a vowel.[/quote]

I don't know which one is actually correct. But the beginning of the word 'one' (or the 'w' sound in general) does sound somewhat like a vowel because it has a bit of the 'u' sound. Even the 'v', which is similar to 'w', doesn't have that slight vowel sound.

"A" + "one" sounds redundant. But I can't find any rules against it. "An hour" might be better.

But, to answer your question: A one-hour nap.

This isn't a dumb question. It highlights one of many exceptions derived from the inconsistencies found in the English language. A lot of native English speakers aren't 100% fluent because it is difficult to remember these rules.

if you divide the A by the spanish written version of pollo then it would be a infinite conjunction but since you use a vowel that contains the ah eh e oh oo it will become a an but american english says it is a definte so it will be "a one hour nap"

'An' cause of grammar-spellin.
though you still pronunce it as "Ah - wohn-'

Usually you use "An" if its followed by "a".