Friedrich H)A09K25 Manual De Usuario

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14
Indoor Blower - Airfl ow
The current Vert-I-Pak 9, 12, & 18 use a dual shaft, permanent 
split capacitor, single speed motor to drive indoor blower and 
outdoor fan.  Earlier model VERT-I-Pak units used 2-speed 
motors.  The Vert-I-Pak 24 uses an individual, single shaft, 
permanent split capacitor, single speed motor for the indoor 
blower, and a separate motor drives the outdoor fan.
Different size (HP) motors and/or different diameter blower 
wheels are used in different models to obtain the required 
airfl ow.
Indoor Blower - Airfl ow
The current Vert-I-Pak 9, 12, & 18 use a dual shaft, permanent 
split capacitor, single speed motor to drive indoor blower and 
outdoor fan.  Earlier model VERT-I-Pak units used 2-speed 
motors.  The Vert-I-Pak 24 uses an individual, single shaft, 
permanent split capacitor, single speed motor for the indoor 
blower, and a separate motor drives the outdoor fan.
Different size (HP) motors and/or different diameter blower 
wheels are used in different models to obtain the required 
airfl ow.
Condenser Fan Motors
The current Vert-I-Pak 9, 12, & 18 units use a dual shaft, 
permanent split capacitor, single speed motor to drive indoor 
and outdoor fan.  Earlier models used a 2-speed motor.  The 
Vert-I-Pak 24 uses and individual, single shaft, permanent 
split capacitor, single speed motor for the outdoor fan, with a 
separate motor driving the indoor blower.
Blower Wheel Inspection
Visually inspect the blower wheel for the accumulations 
of dirt or lint since they can cause reduced airfl ow. Clean 
the blower wheel of these accumulations. If accumulation 
cannot be removed, it will be necessary to remove the 
blower assembly from the unit for proper wheel cleaning.
Cooling
A nominal 400 (350-450 allowable) CFM per ton of airfl ow 
is  required  to  insure  proper  system  operation,  capacity, 
and effi ciency. Factory-set blower speeds should provide 
the proper airfl ow for the size (Cooling capacity) of the unit 
when connected to a properly sized duct system.
Cooling (VEA/VHA 24)
When the thermostat is set for cooling mode (SYSTEM 
switch set to COOL and FAN switch to AUTO) a rise in room 
temperature will make It also causes a 24-volt signal on the 
“Y” thermostat conductor through the high pressure and low 
ambient switches energizing the compressor relay, turning 
on the compressor and outdoor fan motor. A 24-volt signal 
on the “G” thermostat terminal to the Fan Relay, turning on 
the indoor blower motor. 
Heating (Electric)
When using electric heaters, select the blower speed that 
provides adequate airfl ow across the elements to prevent 
overheating and cycling on limit and/or premature failure.
CHECK THE EXTERNAL STATIC PRESSURE, and then 
consult the AIR FLOW DATA to determine the ACTUAL air 
fl ow delivered for the factory selected fan speed.  This will 
be especially important on change-outs using an existing 
duct system that may not have been properly sized to 
begin with.
Heating (VEA/VHA 24)
When the thermostat is set for heating mode (System switch 
set to HEAT and FAN switch to AUTO) it will make a 24-
volt signal on the “B” thermostat terminal to energize the 
Reversing Valve Relay.  A drop in room temperature, will 
make a 24-volt signal on the “W” thermostat terminal to the 
Defrost Thermostat, and “G” thermostat terminal to the Fan 
Relay.  The Defrost Thermostat will determine whether the 
unit should run in Heat Pump, or Electric Heat, based on the 
outdoor temperature. (See Defrost Thermostat page 24)
External Static Pressure
External Static Pressure can best be defi ned as the pressure 
difference (drop) between the Positive Pressure (discharge) 
and the Negative Pressure (intake) sides of the blower.  
External Static Pressure is developed by the blower as a 
result of resistance to airfl ow (Friction) in the air distribution 
system EXTERNAL to the VERT-I-PAK cabinet.
Resistance applied externally to the VERT-I-PAK (i.e. duct 
work, coils, fi lters, etc.) on either the supply or return side 
of  the  system  causes  an  INCREASE  in  External  Static 
Pressure accompanied by a REDUCTION in airfl ow.
External Static Pressure is affected by two (2) factors.
1.  Resistance to Airfl ow as already explained.
2.  Blower Speed. Changing to a higher or lower blower 
speed will raise or lower the External Static Pressure  
accordingly.
These affects must be understood and taken into consideration 
when checking External Static Pressure/Airfl ow to insure that 
the system is operating within design conditions.
Operating a system with insuffi cient or excessive airfl ow 
can cause a variety of different operating problems. 
Among these are reduced capacity, freezing evaporator 
coils, premature compressor and/or heating component 
failures. etc.
System airfl ow should always be verifi ed upon completion 
of a new installation, or before a change-out, compressor 
replacement, or in the case of heat strip failure to insure 
that the failure was not caused by improper airfl ow.