Cool air is heavier than warm air. Your
furnace should have 2-speed blower and larger ducts. 4-inch ducts are too small and will cause shorter equipment life.
Household air humidity is between 20-40%
55 degree liquid refrigerant goes into the evaporator, boils at
72 degrees (becomes gas) from the heat it takes from the outside air. The cool air is then blown into the home through the
evaporator. The 72-degree gas goes to the compressor and gets compressed to raise the temp to 150 degrees. The 150-degree
gas goes to the condenser coils and is cooled to 15-20 degrees warmer than the outside air. The compressed gas goes through
the condenser coils that uses water or air to cool it to 55 degrees again.
65 ambient degrees is the breaking point.
DO NOT OPERATE.
Get the original warranty of the compressor manufacturer from the sellers to see if they are transferable.
Most compressors have a sump heater so the lubricating oils won’t absorb the refrigerant and therefore not lubricate.
The sump heaters are running all the time. A compressor that has been shut down can not be safely started unless the oil has
been purged from the refrigerant. The sump pump must be turned on at least 24 hours before. If the compressor shell is not
warm, do not operate the A/C. Not all compressors have a sump pump or oil heater.
Some compressors have time delays
of 2, 3 or 7 minutes. Also compressors should be free of vibration and perfectly level for proper lubrication.
Water-cooled
condenser systems can be inside the home and are usually found inside the air handler cabinet. The water should be returned
to the ground well. Water cooled systems use a lot of water and is illegal in some towns.
About 70 square inches
of evaporator are needed per ton of air-cooling. Airflow through the evaporator should be 400cfm/ton of cooling. If the coils
are ice covered there may not be enough refrigerant or not enough air volume moving over the evaporator coils.
The
compressor is usually mounted below the evaporator. If it isn’t look for a filter that absorbs moisture in the line.
Filters are very important for A/C efficiency. If they are dirty you can bet the evaporator fins are dirty and clogged.
Supply and return ducts should be equal in cfm.
The temperature of the air before and after it passes through
the evaporator should be 15-20 degrees colder than the ambient air. If the air leaving the evaporator is over 60 degrees,
there may be too little refrigerant or too much air passing over the coils is the result of a to high speed fan or too large
a fan, or the equipment is too small for the house. Conditions that may cause the air leaving the evaporator to be less than
55 degrees include a dirty filter, clogged evaporator coils, fan speed too low, or a broken fan belt.
The evaporator
should be mounted downstream of the heat exchanger. If it is upstream, it will be subject to condensation and corrosion.
Proper disposal of condensate is necessary because it contains yeast’s, bacteria, fungi and other debris you
don’t want circulating in the house air. It must be discharged in house drains only.
Ideally there should
be a return supply located in every room located on the lower part of a wall opposite the A/C vent located on the upper wall.
If returns are not installed in each room, the room doors must be undercut to insure air will reach the return wherever it
is.
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