I just moved into a rental with a Heil Furnace NUGC100AF01 (maybe 1978-1980?) I've never had a unit like this before. I was surprised by the large pilot light about 2 inches wide and 4 inches high that the guy from the gas company lit. I was also surprised by the hissing noise that the unit makes when idle. (After all it's still summer I don't need heat) and it seams like it is using a lot of gas just for what I imagined would be a small pilot light but is more like if I had a burner turned on on my gas stove from the sound it makes. Does this sound normal? Where can I get info on the furnace/ owners manual? And anyone know Where I find the filter to change it?

Yes, it's normal for the age of the appliance, although 2" X 4" seems a bit big in my opinion. That's why there are no more pilot lights. If this is a rental, the landlord should change the filter. However, it could be anywhere, next to the heater, in the cold air return side or even in the grills, or in a large 20X24" or so wall grill. Some people turn off the pilot for the summer but who will relight?