What is the allowed offset on a 2100 Ventis chimney?

Since a completely vertical chimney provides optimal draft, it is best to avoid elbows if at all possible. However, when elbows are necessary to avoid obstructions such as joists, rafters, etc., use no more than two pairs of elbows (total of four elbows) that do not exceed a maximum angle of 30 degrees. You can also use one set of elbows (total of two elbows) that do not exceed a maximum angle of 45 degrees.