If you are installing a Laser Heater and your wall is greater than 9 inches thick, you will need a Flue Pipe Extension.
Please refer to the following chart and NOTE that these flue pipe extensions are only compatible with the new style (two-piece) flue pipes, Part # 20479891:
Up to 9 inches 20479891 None
9 inches to 13 inches 20479891 20479887
13 inches to 16 inches 20479891 20479873
16 inches to 20 inches 20479891 20479874
20 inches to 24 inches 20479891 20479875
These parts are for thick walls. If you need to offset your flue pipe to the left, right or above your heater, you will need an extension kit. We also have those available in our Web Store.