Whatever else I may be able to offer this forum, I am a very amateur chemist. I was wondering (and I have searched the forum and the net, and so I know this is possible but I'm not quite sure how it is done) how I might make potassium nitrate from potash. I was thinking of using ammonium nitrate in the process, which I have (I do not have sodium nitrate) but I am unsure where to go after that. Any help would be greatly appreciated. Thank you.

Just dissolve them both in water and boil it until theres no ammonia released, then chill (or boil the water down) the solution and collect your KNO3. Not very fast method, but you get pretty pure KNO3 this way..

K2CO3 + 2NH4NO3 => 2KNO3 + CO2 + 2 NH3 + H2O

Jackhammer, I think I accidentally disapproved your answer to this topic.
You asked how long you need to boil it, right? Of course that does depent on the amounts you use and how much heat you apply. If you had read Guerilla's post post you would know that you need to heat it until the NH3 has been given off almost completely (it may become necessary to add some more water during that process), then you can evaporate the liquid and have KNO3 left.