Air conditioning methods

There are several methods for air conditioning homes/apartments.

A. Chilled Water Air Conditioning System

This system generates cold/hot water (depending on the season) in a device called a chiller.
The water is distributed by a pump and pipes into interior fan coil units.
Eventually, each air conditioned room or space is equipped with a fan coil unit that can be turned on and off to regulate the temperature (for example, hotels).

Method Advantages

  • Compact device
  • Maximum reliability
  • System lifetime: ~15-20 years
  • Maintaining homeowners’ value – Serves as a factor among realtors and real estate professionals. When a chiller is installed in a home, it is considered to be of greater value. Low maintenance requirements.
  • Saving on the main electrical service size as compared to the method of split or mini-central air conditioning units.
  • Approximately 20% savings on electricity as compared to a mini-central system due to duty factor (you cannot be at all places at once and the system automatically regulates itself). MethodDisadvantages
  • Very expensive in homes.
  • Not many companies are capable of providing long term, rapid and reliable service for these systems in private homes. Compared with mini-central and split air conditioner systems Expensive ongoing maintenance annual costs.
  • Spare parts supply that is not always readily available.

B. Mini-Central Unit

In this method, a mini central unit is installed, air conditioning several rooms simultaneously (in private homes, it is usually one unit per floor – for example). This system is the most popular in Israel due to its price.

Method Advantages

  • Relatively low price, approximately one third the cost of a chiller system (depending whether the system is installed with sheet metal ductwork or flexible duct). The price sometimes includes ceiling height adjustments, depending on the type of unit and the installer.
  • A compact system in which the condensing unit is usually situated near the laundry balcony. The internal unit is concealed over an acoustic ceiling.
  • Low maintenance requirements (where installation was performed properly). There are systems whose maintenance only involves cleaning the filter once every few months.
  • Leading air conditioning companies have achieved high levels of production and reliability. A high level of product reliability means that where the installation was properly performed, the unit will operate without fault for many years.
  • Spare part and of the shelf product availability for immediate supply – as soon as the repair is required.

Method Disadvantages

  • It is impossible to regulate the temperature for each room unless an electrical damper and thermostat is installed in every room, rendering the system more expensive and complicating its maintenance.
  • Maximum electrical connection to the home (since it is impossible to plan the system with a duty factor, as with the chiller, the electrical hookup must include all air conditioning units inputs in the house).
  • Average lifetime: ~8-10 years.
  • Multiple condensing units (private homes, not apartments) cause higher maintenance requirements over time.
  • Relatively high electrical consumption compared to other methods.

Split Air Conditioners

This method entails the installation of a split air conditioner in each room.

Method Advantages

  • Relatively inexpensive, about 15% cheaper than the mini-central method, depending on the manufacturer.
  • Electrical savings – The unit is operated in rooms requiring air conditioning and not in unoccupied rooms.
  • Extensive savings with inverter air conditioners.
  • Allows for pacing the monetary investment over time. Units are installed where necessary and the system is completed when the budget permits it.
  • Low maintenance level in which, if correctly installed and if the condensing unit is placed in a clean and ventilated area, the filter is cleaned once every few months.

Method Disadvantages

  • Multiple condensing units (“external engines”) create an architectural problem and there is not always enough room for them (there can be 6-7 units in a private home, causing a problem for the placement of the external unit, unless there is an available roof).
  • If all units are operating in the house, there will be a greater level of electrical consumption compared to the other methods seeing that the small compressors are not maximized (but usually, not all units are operated at the same time), unless the air conditioners are operated by the inverter method, in which case there are high electricity savings.
  • Design level – Some architects are not pleased with air conditioners in the house and prefer concealed solutions.
  • The level of distribution does not allow maximal comfort. In large spaces, such as the living room, the temperature near the air conditioner is different from the temperature when standing far from the unit. This is especially evident for heating and may cause colds due to the temperature difference (thus, split air conditioners are not recommended for large spaces, but rather mini central units with proper distribution). In addition, it is important to ensure that the bedroom air conditioner is installed in a manner that prevents the air from being directly blown onto the occupant seeing that the air temperature when leaving the air conditioner is very low and may cause neck pain, sneezing etc.

VRF (Variant Refrigerant Flow) System – Such as Mitsubishi, Daikin or equivalent.

This system is innovative and popular in Japan and Europe. Applying this method, a central condensing unit is equipped with variable speed compressors, which regulate their operation according to the home utilization.
When usage is low, the compressor will rotate more slowly and consume less electricity. When the consumption level increases, the compressor will spin faster in order to meet the demand and will consume more electricity.

Method Advantages

  • Savings on the size of main electrical service at home.
  • Saving on electrical consumption – This is the most economical method of all.
  • Smaller interior units and saving on physical space in the home.
  • High technological level.

Method Disadvantages

  • Very expensive – About 15% more expensive than the chiller system, depending on the manufacturer.
  • There are not enough installers who are proficient with this method – an average installer who did not undergo training by the companies marketing the unit, is unable to successfully install the system. Thus, if you have decided to install such a system in your home, be sure to obtain a list of installers recommended by the engineer or marketing companies and get a quote from them only.

Mini Central Unit

with a variable speed Compressor based on Output – Regulating with electrical dampers in the rooms.
Same as above, but the compressor has variable speed, which reduce output and save on electricity when lowering the load.
The technology is different than the VRF method and not as economical on electricity. However, it is economical compared to a regular mini-central system.


  • Saving on electricity


  • Significantly more expensive than mini-central units. The return on the investment between the original cost of installation and the cumulative savings on electricity over time, is 5 years and even more in private homes and apartments (in offices, where air conditioners work more than in residential units, the difference between costs and savings may be repaid within 3 years and this is where such units are worthwhile in planning and installation.
  • The compressors are not available for immediate replacement in the event of failure.
  • Incorrect system planning will cause air flow noises when the dampers in the room close upon reaching the desired temperature.
  • A system with electrical dampers requires more maintenance over the years.
  • The annual service cost (insurance) is higher than with simple mini units.
  • These units are slowly coming off of the production lines and are being replaced by inverter air conditioners!

Leave a Reply

Your email address will not be published. Required fields are marked *