One of the most common faults I see in my day-to-day work as a chimney sweep is the installation of parts being the wrong way round. Chimneys work off negative pressure, which means that smoke will not escape the system as it is constantly ‘sucking’ in air. Thanks to this, we do not need to worry about funneling the gases up the chimney but do need to consider what will happen if debris falls down the flue. It is not uncommon for small amounts of moisture to be present inside chimney systems, either through condensation or rainwater. Any liquid in the flue will run down the inside of the liner and, if installed the correct way round, will funnel into the next until it makes its way down the flue to the bottom. However, if the flue is installed upside down, the liquid will escape the flue system and begin running down the outside of the next flue pipe, causing it to ‘streak’ and eventually rust. In many cases, this moisture makes its way to the top of the stove and rusts the appliance itself.
So, which way is the correct way? Well, as you can see from the diagram above, when pointing the female end up, any debris is naturally funneled down the flue system. On the other hand, when the male end is pointed up, it seeps between the two ends of the flue pipe and ends up escaping from the system. Therefore, it is imperative that the flue pipe is pointed with the female end up to funnel any debris down the flue.
With some European stoves, you may need to purchase a female-to-female adapter for the flue collar in order to ensure the flue pipe is facing the correct way.