FloAire FAV-M - Manual (Page 24)

24
AIR BALANCING
The Direct-Fired Gas, make-up heater requires the correct air flow velocity across the burner. The burner
profile opening creates a pressure drop which increases the air velocity across the burner. The air flow
switch monitors the pressure difference, and will open the burner circuit if pressure difference is not
correct. The air flow switches have low and high pressure settings. The pressure drop should not be
near the minimum and maximum of the air flow switch. Balancing may be required to fine tune the burner
profile pressure drop. The air flow pressure drop should be checked in fresh and return air modes on the
re-circulating heaters. See the specifications and instructions below on air balancing a re-circulating
heater.
Unit Type Air Flow
Switch
Part Number
Low
Setting
In. W.C.
High
Setting
In. W.C.
Target Pressure
Drop In. W.C.
Natural Gas
Target Pressure
Drop In. W.C.
Propane Gas
Re-circulating DDP-106-256 0.15” 0.95” 0.45” – 0.65” 0.45” – 0.65”
The pressure drop should be checked with the burner off or operating at 70 degree discharge if ambient <
65 degrees. Read the pressure drop at the extra probes supplied with the blower ON. This should be
repeated in fresh and return air modes.
WARNING!!
Disconnect power and close all gas valves before and while making burner profile adjustments.
The heaters profile and damper openings are
sized to the units designed airflow. While
balancing the unit to jobsite static pressures the
profile and damper blank-off plates may need to
be moved to achieve the correct air flow
pressure drop.
If the pressure drop is too high, in fresh and
return air mode, remove or adjust the bypass
fresh air and return air damper blank-off panels,
which will decrease the pressure drop. If the
correct air flow pressure drop is still not
achieved adjust the blower drives to decrease
the blowers RPM.