Where should the hole in the flue pipe for combustion testing be located?

The hole in the flue pipe for combustion testing should be located as close to the breech as possible. This positioning allows for the most accurate measurement of combustion gases immediately after they leave the combustion chamber. By placing the testing hole near the breech, you can effectively assess the efficiency of the combustion process and identify any potential issues related to flue gas exhaust. This spot ensures that the sampling reflects the conditions as the gases exit the appliance, providing insights into the performance and safety of the heating system. Accurate combustion testing is critical for ensuring that the system operates efficiently and safely, thus maintaining optimal indoor air quality and compliance with regulations.