I just bought this unit used and noticed the a-coil is bigger than the top of my furnace. Do I need to get another a-coil or build a bigger plenum for my furnace.

Air Conditioning is easier to add to an existing central hot air heating system then you might think. Both systems use air to move the heating or cooling to the different parts of the house. With the addition of a coil and condenser to your system you can stay nice and cool all summer long.

The easiest way to add in cooling to a system is to install a coil on top of the furnace supply air plenum. This can be accomplished by cutting open the supply duct just on top of the furnace and sliding the air conditioning coil right in on the top of the furnace. The only limitation usually is the height of the plenum. If there is not enough height there, then the coil may need to be installed on a horizontal run.

If the horizontal run option is needed then you will have to make sure that all of the air flow goes through the run. If all of the air does not go through that run, then the ones that do not go through will not cool nearly as effectively as the rest of the runs that go through the coil.

After placing the coil in the ductwork, the piping and electric will need to be run to the outdoor condenser unit. After wiring and piping the unit the refrigeration lines will need to be purged, and vacuumed. This will clean the lines and take the air out of them. Any air in the system will cause the system not to work properly.

When all of this work is done you will be ready to have great cooling. The whole process usually takes me less than a day to complete. Adding cooling to an existing system is a simple operation when it is done by someone that has done it many times. If you have a hot air central heating system without the benefit of cooling, then you should check into adding the cooling feature to your system. You will be glad you did when the hot weather rolls back around again.