Desert Aire Aura QS, Installation And Operation Manual

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adjustment screw counterclockwise to decrease the pressure or clockwise to increase the
pressure. ADJUSTMENTS TO THE LISTED PRESSURE MUST NOT EXCEED 0.3” wc.
A 0.3” wc adjustment will increase or decrease the input approximately 0.4%. Replace the
screw cap when the adjustment is complete.
Shut off the gas supply to the furnace. Remove the pressure gauge and re-install the pipe
plug using a threaded compound resistant to the action of LP gases.
If the rated input cannot be obtained with the present orifice at the correct pressure, your local
gas supplier will assist in sizing the proper orifice. The Desert Aire Service Department will
gladly help you size the orifice if you provide them with the heating value in BTU per cubic foot
and the specific gravity of the gas.
3.2.1 Burner Adjustment
TotalAire™ and Aura™ units only: Burner air shutters are not normally required
on natural gas furnaces. Air shutters are required on propane gas units and may
require adjustment. Before making any adjustments to the air shutters, allow the
heater to operate for about fifteen minutes with the air shutters open. The slotted
screw on the end manifold bracket moves the air shutters and adjusts all burners
simultaneously. Turning the screw clockwise opens the shutters; counterclockwise
closes the shutters. After the furnace has been in operation for 15 minutes, close the
air shutters observing the flame for yellow-tipping. Open the shutters until the yellow
disappears. A limited amount of yellow tipping is permissible for liquefied petroleum
gases. Natural gas should not display any yellow-tipping. When making the adjustment,
close the air shutters no more than is necessary to eliminate the problem condition.
After 15 – 20 minutes of continuous operation, the air temperature rise across the
burner must be no higher than 85°F. If the outlet or supply duct temperature is too
high, you must balance the supply airflow.
3.3 Airflow Balancing
To ensure code compliance and long equipment service life, proper airflow must be verified by
a qualified air balancer. Shut off the compressor to prevent the refrigeration from running while
you balance the air. If the unit is equipped with a Supply Fan Variable Frequency Drive (VFD)
then the blower speed will be modified at the VFD.
Unit airflow rate is specified at the time of order. The flow rate each unit has been designed for
is indicated on a label near the air balance ports. A pressure differential across a fixed set of
components that corresponds with the flow rate is shown on the label as well. This is a
convenient method of setting and checking the flow. Alternatively, external test and balance
may be completed with velometer, anemometer, flow hood, or other testing devices. In all
cases the flow rate should be set according to the label to ensure appropriate operation and
system reliability.
Desert Aire - QS/QV Manual