Boiling means there is a pressure loss of the cooling system. Did you check your radiator cap? You did not mention the radiator cap in your first post.
A 15 psi cap and 50/50 coolant water mix should not boil until 250f, therefor if
you did not loose pressure and you were boiling, you WERE very HOT.
You stated you replaced a coolant elbow, was that the source of your pressure loss?