Tips for Selecting Matched Components and Line Sets

Tips for Selecting Matched Components and Line Sets
For an air conditioning or heat pump system to provide proper comfort, efficiency and
operation, it is very important for all the components to be matched and sized properly.
Below are a few tips for selecting matching components and line sets your system:
1) When purchasing an air conditioner or heat pump, it is critical that it be matched with an
appropriate evaporator coil or air handler (which has an evaporator coil built in). Evaporator
coils are sized based on their capacity in tons and the SEER rating (efficiency) of the system.
Typically, the higher the SEER rating or tonnage of the system, the larger the evaporator coil
needs to be. It is vital that the air conditioner or heat pump be matched with a properly sized
evaporator coil. An improperly sized coil, particularly one that is too small, can lead to the failure
of the compressor after just a few seasons of operation.
When purchasing a new 13 SEER air conditioner or heat pump you will typically purchase an
evaporator coil with the matching tonnage rating. However, when purchasing a system with a
SEER rating higher than 13, it is often necessary to purchase an evaporator coil with a higher
tonnage rating than that of the air conditioner or heat pump. Use the manufacturer’s specification
sheet to identify the correct match for your condenser. Similarly, do not match a new condenser
with an older evaporator coil designed for a lower SEER system. Even if that coil has the same
tonnage rating as the new system, it will not be the proper size for a 13 SEER or higher system.
2) When purchasing refrigeration lines, measure the length of line set needed to connect your
outdoor condenser to the indoor forced air equipment. Based on that length, the correct size
diameter line set can be selected which will ensure your system meets the listed SEER rating
and capacity. Once you have accurately measured the length needed, use our chart below to find
the diameter best for your system.
3) When feeding a new line set through the wall, it is typically easier to feed the lines “out” from
the inside of the home rather than “in” from the outside. This will also minimize any damage to
the suction line insulation when feeding it through the wall. It is always advisable to slowly roll
the lines open to avoid putting crimps in the copper. If you encounter a tight radius bend, cut
the suction line and braze a 90° or 45° fitting to avoid kinking the flexible tube. The installation
DVD includes more tips on running line sets.
4) When sweating the line set to the equipment or fittings use an oxygen/acetylene torch
(preferred since it is hottest) or MAPP gas torch and high silver content brazing rods to achieve a
proper brazed connection. Propane gas or MAP/PRO torches should *not* be used, since they
will not generate enough heat to make a good connection. When brazing pipes into air
conditioning condenser or heat pump, first tie a wet rag around the service valves to dissipate
heat. If this isn't done, there are small rubber O-rings in the valves which can melt and cause
refrigerant leaks. If you aren't familiar with using a torch, for your safety have your air conditioning
contractor perform this task for you. Wear proper eye and hand protection when operating a torch.
5) Once all of the line set connections have been brazed, a vacuum must be pulled on the
system to evacuate the lines. The manufacturer's installation instructions describe the system
evacuation process. If your system operates on R22, then by law you must have an HVAC
technician do this part of the job for you.