Figure 4-18.Electrical circuit showing how blower control operates blower motor when temperature in plenum rises.
Patterns of air distribution vary with the positions
of supply diffusers. A diffuser that discharges through
the floor in an upward direction or downward through
the ceiling provides a vertical distribution of air. On
the other hand, a diffuser that discharges through a wall
provides a horizontal distribution of air. The spread for
either the horizontal or the vertical pattern depends on
the setting of the diffuser vanes. A low horizontal
discharge provides the most effective distribution
Airdistribution that results from different diffuser
locations is shown in figure 4-19.
As previously mentioned, warm-air heating systems
are generally identified as either the GRAVITY TYPE or
the FORCED-AIR TYPE. The type of duct distribution
used further identifies these installations. There are two
Figure 4-19.Air diffuser distribution.