Ruud ANL-AZ 13 SEER Series, Installation Instructions Manual

20

The air distribution system has the greatest effect 

on airflow� The duct system is totally controlled 

by the contractor� For this reason, the contractor 

should use only industry-recognized procedures�
The correct air quantity is critical to air 

conditioning systems� Proper operation, efficiency, 

compressor life, and humidity control depend 

on the correct balance between indoor load 

and outdoor unit capacity� Excessive indoor 

airflow increases the possibility of high humidity 

problems� Low indoor airflow reduces total 

capacity and causes coil icing� Serious harm can 

be done to the compressor by low airflow, such as 

that caused by refrigerant flooding�
Air conditioning systems require a specified 

airflow� Each ton of cooling requires between 350 

and 450 cubic feet of air per minute (CFM)� See 

the manufacturer’s spec sheet for rated airflow for 

the system being installed�
Duct design and construction should be carefully 

done� System performance can be lowered 

dramatically through bad planning or workmanship�
Air supply diffusers must be selected and located 

carefully� They must be sized and positioned 

to deliver treated air along the perimeter of the 

space� If they are too small for their intended 

airflow, they become noisy� If they are not located 

properly, they cause drafts� Return air grilles must 

be properly sized to carry air back to the blower� If 

they are too small, they also cause noise�
The installers should balance the air distribution 

system to ensure proper quiet airflow to all rooms in 

the home� This ensures a comfortable living space�

These simple mathematical formulas can be used 

to determine the CFM in a residential or light 

commercial system�
Electric resistance heaters can use:
 

CFM = volts x amps x 3�413

  SHC x temp rise

Gas furnaces can use:
 

CFM =    Output Capacity in BTUH*

         SHC x temp rise

*Refer to furnace data plate for furnace output capacity� 
SHC = Sensible Heat Constant (see table below)

An air velocity meter or airflow hood can give a 

more accurate reading of the system CFM�
The measurement for temperature rise should be 

performed at the indoor coil inlet and near the 

outlet, but out of direct line of sight of the heater 

element or heat exchanger� For best results, 

measure air temperature at multiple points and 

average the measurements to obtain coil inlet and 

outlet temperatures� 

START-UP

Start-Up

At initial start-up or after extended shutdown 

periods, make sure the crankcase heater is 

energized for at least 12 hours before the 

compressor is started� (Disconnect switch is 

on and wall thermostat is off�) 

Connect the communicating system according to 

the wiring diagram on page 17� Once all devices 

are connected, power up the line and low voltage 

to the system� When all devices are powered, the 

thermostat should detect the indoor and outdoor 

units within 45 seconds�
Even though the unit is factory-charged with 

Refrigerant-410A, the charge must be checked  

to the charge table attached to the service panel 

and adjusted, if required� Allow a minimum of  

15 minutes of run time before analyzing charge�

Checking Airflow

ALTITUDE  

(FEET)

SENSIBLE HEAT  

CONSTANT 

(SHC)

ALTITUDE  

(FEET)

SENSIBLE HEAT  

CONSTANT 

(SHC)

Sea Level

1�08

6000

0�87

500

1�07

7000

0�84

1000

1�05

8000

0�81

2000

1�01

9000

0�78

3000

0�97

10000

0�75

4000

0�94

15000

0�61

5000

0�90

20000

0�50

Airflow

Start-Up