Why is my wall furnace so thunderous? I had a topical wall furnace installed in my home 2 months...

I had a topical wall furnace installed in my home 2 months ago. It make loud popping noises everytime it comes on and sour, for about 10 minutes. The heat company that installed the furnace told me this is due to the metal expanding during heating and in that is nothing that can be done nearly this. They also said that this is a common problem near wall furnances. Is this true? The company has tried to loosen the screw to relieve pressure but this has not help. Thanks for any info.
Hello its Paul again roughly speaking the introduction.?
Answers:    Ask the furnace people if it is viable and past the worst to put in insulation IE:Fiberglass between the outside doors to hang on to the banging down to a roar.
Could this be a rumford firebox & can...
OMG, I am so jolly you asked this question. I enjoy the SAME problem with my wall furnace and it is driving me crazzzzzy. It's not that loud; I in actual fact only make out it when the house is quiet and I'm going to bed. I be too lazy to look into it, but very soon that I see someone else is having impossible to tell apart problem, there's probably not much we can do :-(