Draft-Type Vents
A draft test determines whether or not combustion products from the boiler are venting properly through the chimney. Insufficient draft (also known as “positive draft” can cause combustion products (exhaust) to quickly back up into the home of a draft-hooded boiler. This can lead to carbon monoxide poisoning or even death for the building occupants.
Causes of poor draft include chimney or flue pipe blockages from animals or objects, improper firing rate of the appliance, improperly sized vent piping or an improperly sized chimney.
Power Exhaust Vents
Combustion products from a boiler equipped with a power exhaust vent can also back up into the home if there is a problem with the venting system.
Problems can occur with this type of venting from improper sizing or vent system design, such as oversized/undersized piping, incorrect materials, mixing different vent piping materials, improper pitch of vent lines and insufficient removal of condensation. Blockages can also cause issues. Common examples include bees nests, bird nests, objects placed in the termination fitting and anything else that could cause a restriction in the flow of exhaust.