What is the Best Insulation for an AC Unit?

Common materials for air conditioner insulation wrap include foam rubber, polyethylene foam, and fiberglass. Among these, the best balance between cost and effectiveness is found in polyethylene foam products. They have closed-cell designs to prevent moisture from entering. If you only need to fill small cracks to fill a little space, choose spray foam.

Many of these spray foam products are designed specifically for this task, but you must continue to work slowly and carefully to prevent the foam from spilling into unwanted areas. Spray foam hardens almost immediately and can be very difficult to remove. In addition, wear protective gloves and goggles and always follow the manufacturer's instructions. Closed-cell insulations are commonly used for air conditioning, refrigerant copper pipes, and drain pipes.

Many air conditioners and coolers also used closed-cell insulation for their internal pipes and body. Polyurethane (PU) insulations are commonly used for air conditioning cold water pipes. PU insulators can also be found on the panel of air handling units (AHU). Most cold water pipes have around 2″ of PU insulation.

However, the thickness of the insulation varies slightly with the size of the pipe. In addition to thickness, the density of PU insulation is also crucial for its insulating strength. Like pre-insulated cold water pipes, the AHU panel is also prefabricated. The AHU are always isolated on their own and, therefore, no additional insulation is required in situ. AHU panels are usually 25mm or 50mm thick, depending on the requirement.

Fiberglass insulation can be found in the ducts of air conditioning systems. The insulation of flexible ducts used in air conditioning is always made of fiberglass. The rigid ducts of the air conditioning system are usually insulated with fiberglass insulation. Fiberglass insulation is soft and swollen, but it is harmful to humans when inhaled.

Fiberglass insulation usually has a layer of aluminum foil on the outer surface to protect and contain the fiberglass. Adhesives or glues are required to install fiberglass insulation in rigid metal ducts. Flexible ducts are usually pre-insulated at the factory rather than on site. On the other hand, fiberglass insulation for rigid ducts is usually wrapped in situ. Rigid ducts that are insulated with fiberglass are usually shiny (due to aluminum foil) and wrinkled.

Fiberglass insulation usually comes in the form of a rolled blanket. Installers should cut it themselves as needed, stick it to the aluminum foil, and wrap it around the rigid ducts. The blanket shape is ideal for uneven surfaces. In addition, fiberglass insulations also come in plate form, where they are pre-cut to certain sizes.

The plate form is usually used to soundproof a room by installing it on the wall. In addition, fiberglass insulation can also be installed on the inner surface of rigid ducts to absorb noise from air conditioners. Fiberglass insulations are prone to overcompression because they are so soft. Overcompressing fiberglass insulation can reduce its insulation resistance by up to 50%. Fiberglass is naturally fire resistant, although it looks like a type of cotton that can easily catch fire.

It is strongly recommended to wear a pair of gloves and a mask when handling fiberglass, as inhaling it is harmful and contact with it can cause itchy skin. Polyethylene (PE) insulation is commonly used for rigid ducting in air conditioning systems. PE insulations can also be found in the body of some types of air conditioners, such as fan-coil units and ceiling cassettes. For non-hidden ducts, PE insulation is generally preferred to fiberglass insulation because of its better appearance. Unlike wrinkled fiberglass insulation, PE insulations are firmer, which causes them to remain flat in the ducts. However, PE insulations are more expensive than fiberglass insulations and are therefore less preferred for hidden ducts.

PE insulations cannot absorb noise like fiberglass insulations do. Therefore, they are not found on the inner surface of rigid ducts. However, PE insulation is much easier to repair compared to fiberglass insulation. While fiberglass is fire resistant, polyethylene is combustible. However, polyethylene can become fire resistant when treated with flame retardant chemicals.

Meanwhile, PE insulations are not harmful like fiberglass insulations do. Rockwool is actually a company name; its scientific name is rock wool. Rockwool manufactures stone wool which has become so popular that people use rock wool instead of rock wool when referring to insulation material. Rock wool is soft but not as soft as fiberglass or polyethylene. Air conditioning ducts do not usually use rockwool insulation; like any other mineral wool it is harmful to humans when inhaled or in contact with it. However, rock wool isn't as bad as fiberglass because it's not as easy to spread as fiberglass; however it is still advisable to wear adequate protection when handling rock wool. Rock wool insulation commonly comes in rectangular shapes; because they are firmer and less harmful than fiberglass they are more popular for use in soundproofed rooms.

In addition rockwool insulators can be used to absorb noise from air conditioners when installed on the inner surface of rigid ducts just like fiberglass insulation. Most often rock wool is preferred to fiberglass because it is less harmful and physically stronger; however rock wool is more expensive than fiberglass so it isn't preferred for flexible ducts or rigid ducts where its weight would cause them to sag due to its inability to stand on its own in a duct. Although rockwool insulators are excellent insulators they aren't preferred for cold water pipes because they can be easily damaged by water; however when it comes to soundproofing rockwool insulators can be used to wrap around an air conditioner and significantly reduce noise. In conclusion there are many different types of materials that can be used for air conditioner insulation wrap; however polyethylene foam provides the best balance between cost and effectiveness while spray foam should only be used for small cracks due to its difficulty in removal once hardened.