IRC for clearance forced air heaters

I need the IRC code for clearance in front of forced air heaters.

Your answers can be found here.

Thanks , I have, that, I should have put this in the emergency section. I was not at my office, and was trying to get a client some info, working off my tablet, For any one that may need it.

IRC 1305.1 All mechanical appliances must be accessible for service and repair without removing permanent construction or other appliances. A level working space at least 30" deep and 30" wide must be provided in front of the service side of the appliance (18" allowed for room heaters)