Gas Flue Installations Lesson

This consists of four principle components:

• Primary Flue
• Draught Diverter
• Secondary Flue
• Terminal or Cowl

Primary Flue:

This creates the initial flue draught (also know as flue pull) required to remove all the products of combustion from the appliance. This comes as part of the appliance.

Draught Diverter:

This does three things:

1. It diverts any down draught from the secondary flue.
2. It allows flue products to be diluted.
3. It breaks the pull of the secondary flue.

The flue pull of the secondary flue depends on the height of the flue and a number of other factors. This pull, if taken to where the burner or flame (combustion chamber) is situated, would have a direct effect on the appliances performance and efficiency.

In certain weather conditions, wind can blow down a flue, thus pushing the flue gases back down the flue (down draught). If allowed to enter the combustion chamber, they would interfere with correct combustion. For this reason the down draught is diverted away from the primary flue and into the room containing the appliance.

Secondary Flue:

The purpose of the secondary flue is to take the products of combustion and the diluted air to the terminal.

Terminal or Cowl:

The terminal is fitted onto the end of the secondary flue, outside the building.

Its main roles are:                                                           

• Assist in taking flue gases from the secondary flue
• Minimise down draught
• Prevent entry of rain and anything likely to block the flue