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There seems to be multiple forms of $\ce{HI}$ used to cleave epoxides:
conc. $\ce{HI}$, anhydrous $\ce{HI}$, cold $\ce{HI}$, hot $\ce{HI}$, cold conc. $\ce{HI}$, hot conc. $\ce{HI}$, etc.
So, does concentration of $\ce{HI}$ and temperature have any significance in determining the product?
for unsymmetrical epoxides or oxiranes reaction takes place in this way:
in acidic medium- ring on reaction with HI ring opens from more hindered side i.e., the more hindered C-O bond. So the carbon in which more number of groups are attached which is bonded to the oxygen in ring gets -I.
in basic medium- the ring opens from less hindered side.
temperature is not a much important factor in this reaction.
