SYSTEM OPERATION
11
This section gives a basic description of heat pump condenser
unit operation, its various components and their basic opera-
tion. Ensure your system is properly sized for heat gain and loss
according to methods of the Air Conditioning Contractors Asso-
ciation (ACCA) or equivalent.
CONDENSING UNIT
The ambient air is pulled through the heat pump condenser coil
by a direct drive propeller fan. This air is then discharged out of
the top of the cabinet. These units are designed for free air dis-
charge, so no additional resistance, like duct work, shall be at-
tached.
The gas and liquid line connections on present models are of the
sweat type for field piping with refrigerant type copper. Front
seating valves are factory installed to accept the field run copper.
The total refrigerant charge for a normal installation is factory
installed in the heat pump condenser unit.
AVZC20 models are available in 2 through 5 ton sizes and use R-
410A refrigerant. They are designed for 208/230 volt single phase
applications.
AVZC20 2-4 ton R-410A model units use a Daikin rotary compres-
sor, while the 5 ton has a Daikin Scroll compressor. Both
compressor types are specifically designed for R-410A refriger-
ant. These models are ComfortNet
TM
ready.
There are a number of design characteristics which are different
from the traditional reciprocating and/or scroll compressors.
AVZC20 models use "FVC" which is
NOT
compatible with mineral
oil based lubricants like 3GS. "FVC" oil (required by the manufac-
turer) must be used if additional oil is required.
Model Name
Compressor Oil
AVZC200241**
FVC50K
AVZC200361**
FVC50K
AVZC200481**
FVC50K
AVZC200601**
FVC68D
COOLING
The refrigerant used in the system is R-410A. It is a clear, color-
less, non-toxic and non-irritating liquid. R-410A is a 50:50 blend
of R-32 and R-125. The boiling point at atmospheric pressure is
-
62.9°F.
A few of the important principles that make the refrigeration cycle
possible are: heat always flows from a warmer to a cooler body.
Under lower pressure, a refrigerant will absorb heat and vapor-
ize at a low temperature. The vapors may be drawn off and con-
densed at a higher pressure and temperature to be used again.
The indoor evaporator coil functions to cool and dehumidify the
air conditioned spaces through the evaporative process taking
place within the coil tubes.
NOTE:
The pressures and temperatures shown in the refrigerant
cycle illustrations on the following pages are for demonstration
purposes only. Actual temperatures and pressures are to be ob-
tained from the "Expanded Performance Chart".
IMPORTANT
To avoid overheating the service valve, TXV, EEV, or filter
drier while brazing, wrap the component with a wet rag, or
use a thermal heat trap compound. Be sure to follow the
manufacturer’s instruction when using the heat trap
compound. Note: Remove Schrader valves from service
valves before brazing tubes to the valves. Use a brazing alloy
of 2% minimum silver content. Do not use flux.
Torch heat required to braze tubes of various sizes is
proportional to the size of the tube. Tubes of smaller size
require less heat to bring the tube to brazing temperature
before adding brazing alloy. Applying too much heat to any
tube can melt the tube. Service personnel must use the
appropriate heat level for the size of the tube being brazed.
