Do Pipes from Air Conditioners Need to Be Insulated for Freezing?

Air Conditioner System

• A central air conditioning system typically uses the same duct work, blower and motor as a home’s heating system. These systems work together as a forced-air distribution system that delivers cool or warm air throughout the home and removes or adds moisture to maintain temperature and comfort levels. A cooling system has an additional component, known as an air condenser, which releases warm, moist air to the outside environment. The two pipes running between the condenser and the air handler or furnace deliver coolant to the air handler and warm air to the condenser. Insulating those pipes can help to improve cooling efficiency during summer months. Instances in which pipes freeze may warrant insulation, depending on the problem's cause.

Moisture Buildup

• Moisture buildup along the pipe surfaces can quickly turn to frost or ice when exposed to freezing temperatures. Moisture buildup develops in areas where warm and cool air or warm air and cool surfaces collide. Warm air molecules can carry heavier concentrations of water vapor than cool air. When the two temperatures combine, the warm air becomes cooler, which causes air molecules to release their vapor in the form of moisture or water. In effect, areas of pipes running between the condenser and the air handler may be exposed to warm and cool temperatures, depending on where pipelines enter and leave the home. When that happens, frost or ice may form on areas of pipe.

Evaporator Coil Freezing

• Freezing can develop during summer months when air conditioning systems are in use. Ice- or frost-lined areas may appear where the system’s evaporator coil enters the indoor air handler device. The evaporator coil connects to the piping and delivers extremely cold liquid refrigerant to the air handler, which disperses cool air into the home.

  Normally, air flow across the evaporator coil prevents condensation from forming. When air flow becomes blocked or impeded, the combined effects of the cold surface and the surrounding air temperature causes moisture to form on the coil’s surface. If left unattended, ice formations will cover the evaporator coil and eventually reduce the system’s cooling capacity. Under these circumstances, pipe or coil insulation may not fix the problem. Causes for this type of freezing include a dirty air filter, damaged duct work and a faulty blower motor.

Low Pressere Inlet Freezing

• Air conditioner condenser units attach to a low pressure inlet line, which sits at the opposite end of the piping that goes from the indoor furnace unit. When frost and ice appear at the evaporator coil, malfunctions can occur at the other end of the pipe where the low pressure inlet enters the condenser unit. Blocked air circulation across the evaporator coil can affect the temperature of the refrigerant that flows through the low pressure inlet. In effect, refrigerant's temperature becomes colder and causes frost and ice formations to appear where the low pressure inlet enters the condenser unit. Because air flow causes much of this problem, insulating the pipeline won’t help. As with the evaporator coil, freezing problems at the low pressure inlet typically result from a dirty air filter, damaged duct work or a faulty blower motor.