HVAC Installation

The indoor unit is referred to as the evaporator and contains the “cold coil” evaporator coil filled with refrigerant. On the other hand, the outdoor unit is comprised of the compressor, condenser, “warm coil” condenser coil, and a fan. If heating is desired, the condenser is known as a heat pump, which can both heat and cool (although often, an A/C is combined with a furnace for heating). As much as 39% of office energy usage and 48% of residential energy usage can be attributed to HVAC systems. Given this significant contribution, it’s important to prioritize energy conservation when selecting the best cooling (and heating) system. To help you make an informed decision, here are some A/C options to consider:
  1. Window-mounted/mobile/portable A/C units require access to a partially open window where a plastic panel is inserted and a flexible duct penetrates it to pull in outdoor air to be cooled. The advantages of these units include their affordability, ease of installation, and no requirement for external design or installation services. They can be conveniently plugged into standard wall outlets without any need for electrical upgrades. However, these units have some drawbacks, such as taking up window and floor space, venting/exhausting some warm air back into the room, and generating a lot of noise. Toshiba RAC-PD0811CRU is an example of this type of A/C unit.

  2. Wall-mounted (ductless) A/C, also known as through-the-wall A/C, is mounted inside a sleeve that has been installed in a space cut into an exterior wall, usually beneath a window.

  3. Packaged terminal A/C (PTAC) is similar to wall-mounted A/C units, but most models combine heating and cooling in one unit. They are usually connected to a building’s hot water system, with hot water produced by the boiler flowing into the unit and circulating the resulting radiative heat into the apartment. These units have a separate chamber containing coolant that produces cool air.

  4. Mini-split (ductless) A/C, a type of split system that is not central air (ducted), comprises wall-mounted indoor units and an outdoor unit placed nearby on a concrete pad.


  1. Toni L. Kamins. “Through-the-Wall Versus PTAC Air Conditioners: A Guide for New Yorkers.” Brick Underground. 15 Jul 2013.
  2. “Window AC vs PTAC “. Applied Comfort.