A:Answer We were not quite clear on your inquiry about "How far from the back wall does this dryer need to be if vented in the back to a side location?" with regards to the LG - TrueSteam 7.4 Cu. Ft. 12-Cycle Steam Gas Dryer - Graphite Steel, Model # DLGX3571V. The dryer vent location on this unit can be changed from the rear to the sides and you would need to purchase an adapter kit, part # 383EEL9001B that contains the necessary duct components. The dryer has knockout tabs on the left-side and at the bottom that you can press to remove for the desired vent location. Right-side venting is not available of Gas models. If you are venting to the rear, you do not need to remove any knockout tabs as the unit is shipped to vent to the rear. Rear venting will require an installation clearance spacing of 5 inches to allow for proper air flow and for the vent duct. If you choose side venting, or bottom venting, you do not need any clearance spacing in the rear, but you will need to attach a supplied cover plate for the rear vent location...^IFV