Secondary Air Tube sizes

[buddha65281]

Hello everyone, it has been about 2 yrs I believe since I last was on this forum, I hope that everyone has been safe and in good health. The reason I am here tonight is to ask why there are 2 sizes of holes in the secondary air tubes and if it matters about installation position?
I had to have my US Stoves Model 2000 replaced due to structural failure, the unit cracked at all 4 corners where the door closes on the main core.
When I contacted US stoves while looking through the installation manual I realized the secondary air tubes were not installed as pictured with the smaller hole tubes in the front. Now I never changed them which means they came that way from the company. The replacement stove also has the larger tubes closer to the door opening but the manual clearly shows and according to the manual indicates that the smaller orifice tubes go closest to the door. my new stove is the US stove model 2500LN(Magnolia) and the old model was model 2000.
Anyone KNOW the correct install and does it really matter which is up front?
Thanks!
Buddha65281

 

[bholler]

Ask us stove company they will know best. But i have seen that cracking on several us stove company stoves so chances are it was nothing you did. But yes the placement of the tubes will make a difference

 

[buddha65281]

Ask us stove company they will know best. But i have seen that cracking on several us stove company stoves so chances are it was nothing you did. But yes the placement of the tubes will make a difference

I have already gotten the new one and I did mention it to the US stove rep but she could not give me a definitave answer on the tube placement. thanks for the reply

 

[buddha65281]

bump

 

[Corey]

Well, I can't speak directly for US stove, but if it is any consolation, an Englander manual (one other that I know of which shows burn tube layout) places the small holes at the back and the larger ones at the front. Though there is only about 0.025 inch difference in the hole diameter... .1625 vs .1875. They are also quite specific about the hole angle...specifying it to the nearest 5 degrees...the very back tube faces forward true horizontal at 270º, the next tube forward is angled up ever so slightly at 275º and so on.

http://www.homedepot.com/catalog/pdfImages/e3/e3dda524-8c99-482d-af74-764abbb59fef.pdf

 

[EatenByLimestone]

I suspect the smaller tubes will show a greater velocity so having the small tubes in front could throw the flame into the door. I don't know if this would cause the cracking, but i can see where it could cause the thin( in width) areas around the door to expand more than designed and possibly crack a weld.