G3 Venting and Combustion Products: What's Tested and How to Study It
Vent systems, categories, draft, and safely removing the products of combustion.
Venting is where a mistake is most likely to hurt somebody, and the exam treats it accordingly. Expect questions on vent sizing, materials, termination and what each appliance category requires.
What this topic covers
Appliance categories I to IV and the vent each demands
Vent materials, and matching them to the appliance
Draft, and what disturbs it
Vent termination clearances
Common venting and shared vent systems
Spillage and how it is detected
How to study it
Get the four appliance categories straight first — positive or non-positive vent pressure, flue loss above or below 17%. Much of the rest follows from knowing which category you are dealing with.