Whether you use a Straight or a U-Tube configuration really depends on several factors. One thing to look at is where you will need to get your gas supply from, and where you would like to exhaust your system. If you want to exhaust through an outside wall, and your gas supply will be located on the opposite wall then you may want to go with a straight tube configuration. If your gas and exhaust will be closest to the same wall then a U-Tube may be your best choice. See sample layouts below if you still need help deciding please give us a call before placing your order, we are here to help. 800-642-2663