National Oilheat Research Alliance 17
Sizing Draft Controls
For most applications, appliance manu-facturers
recommend that the draft control
should be the same size as the flue pipe. Tall
chimneys often require larger controls, as
shown in the draft control sizing chart below.
Draft Inducers
Sometimes the venting system cannot devel-op
sufficient draft to safely vent the combus-tion
gases from the building. Short chimneys,
undersized venting systems, long horizontal
vent runs, negative building pressures and/or
Figure 13