Desert Aire Aura QS Installation And Operation Manual page 56

56
Desert Aire - QS/QV Manual
The compressor is controlled by a PID loop that will modulate the speed of the
compressor to the level necessary to achieve the desired supply air temperature.
It can take up to 15 minutes for the unit to reach steady state during which time, the
noise of the compressor will vary in frequency and intensity. This is normal as the unit
reaches steady state. During steady state operation, it is common for the compressor
to ramp up for short periods (about 30 seconds) in order to ensure proper oil return.
This will not substantially affect leaving air conditions and the unit will return to steady
state within a few minutes.
Oil charge has been confirmed at the factory. In the rare case that the compressor is
observed to ramp up for oil return more than twice per hour, 20 oz additional POE oil
should be added to the system.
While in steady state operation, record the data required for the start-up report. If the
compressor is at maximum speed in steady state operation, it may be operating
outside of design conditions. Check the air flow to verify excessive airflow is not
limiting the heat pump capabilities of the unit. If the supply air temperature set point
was adjusted, return it to its original value.
For TotalAire™ and VerticalAire™ Products
In order to test the unit in heat pump mode, the air temperature entering the reheat
condenser must be approximately 90°F or lower. If the condition entering the
condenser is higher, the unit may run elevated head pressures and a high discharge
pressure alarm may occur.
If a high outdoor air temperature condition prevents the unit from running long enough
to take data, note this on the startup report. During the first Preventative Maintenance
visit that is recommended during spring and fall, the service contractor should
complete the Heat Pump Mode section of the startup report.
To perform start-up checks on the compressor in heat pump mode, the supply air
temperature set point should be higher than the incoming air temperature by at least
10°F and the incoming air humidity and the supply air dewpoint set point should be
higher than the incoming dewpoint by at least 10°F. See the Controller IO Manual for
instructions on setting the supply air and dew point temperature set points. Note the
original setting. Once the set point is adjusted, switch the unit to occupied mode.
It can take up to 15 minutes for the unit to reach steady state. While in steady state
operation, record the data required for the start-up report. If the supply air
temperature set point was adjusted, return it to its original value.