Multi-Apartment Air Conditioning

Single Apartment Systems – Small – Single Indoor Unit

(Quick View Reference: 1a to 1f)

(See also larger 1 to 1 type systems, click here)

A simple air cooled split air conditioning system’s operation involves:-

Heat is transferred between the outside ambient air and refrigerant within the outdoor condensing unit.

  • Refrigerant is delivered from the condensing units to indoor fan coil units within the apartment.
  • Heat is transferred between the refrigerant within the fan coil unit and the air within the conditioned space.
  • The system arrangement includes; a single outside condensing unit, consisting of compressor/s, condenser coil, discharge fan/s and associated electronics serving single or multiple indoor units.
  • Insulated refrigerant piping connected between the condensing unit and each fan coil unit.
  • Associated system control panels and temperature sensors.

small ac condenser
AC Condenser
 small ac condenser sketch

Capacity: Various E.g. 1 kWr to 12 kWr

Condensers Locations:

  • Located on each balcony in accordance with manufacturers requirements.
  • Grouped on well ventilated platforms
  • Within well ventilated plant rooms, typically with fan assisted heat rejection.


Typically with domestic sized units the heat rejection fan have virtually no ability to overcome any external resistance from enclosures and the like.

When grouping condensers, it is critical heat discharged via the fan is able to be removed from the air intake otherwise short circuiting occurs and causes condenser failure.

When groups of condensers are staked above each other (floor by floor) in still conditions a heat plume can be created with the effect that higher floor levels air intake temperature is elevated (thus causing condenser failure).

Locating condensers in car parks is not recommended due to short circulating issues. A small residential condenser can typically have 1900 l/s of discharge air at c. 10 oC above ambient. Thus, for example on a 34 oC day, warm air at 44 oC will occur.

Provision of an isolator per unit is required

Condensate will occur. Provide means to remove

Mount units off floor to limit corrosion.

Provide bi-gold or similar treatment to condenser coils when located in salt areas or in high pollution areas.

Pipework Limitations

The distance between condenser and indoor units horizontally and vertically is limited (and manufacturer particular).

1to1splits pipelengths.png

1to1splits pipelengthstable.png

Note: Each pipe bend reduces the available length of pipework

Pipework should be run in individual apartments space (for that apartments AC condenser) or in common areas


With 1 to 1 units (1 condenser and 1 indoor unit) and wall or bulk head indoor type units then 1 zone only can be serviced per AC condenser.

With a fully ducted indoor unit, supply air is ducted to each space and delivered by supply air device. This system serves all spaces and is sized for peak load of the apartment.

Another fully ducted option is the ‘Day / Night’ system. This has gained momentum as it allows for a smaller capacity unit. The unit capacity being determined typically by the rooms used during the day (main living area and kitchen, typically).

The day night system will need motorised dampers to shut off/control air flow to each zone.


Controls are normally proprietary & supplied by unit manufacturer.

With large apartments with 1 ducted unit serving the entire apartment 1 controller is often provided with inbuilt temperature sensor. Ideally 2 controllers should be provided 1 in day zone, the other in the night zone. Selecting either unit will make that controller the ‘Master controller’ i.e. the unit will control the air temperature to the ‘Master controller sensor.

With Day night zoned ducted units ideally 2 controllers as above should be provided.

Heating & Cooling

Cooling Only

Cooling only systems are suitable where heating of a conditioned space is not required. This is generally not the case.

Reverse Cycle

Reverse cycle systems have the ability to cool and heat, however only simultaneous cooling or simultaneous heating can be accommodated by all fan coil units connected to a single condensing unit. Therefore all rooms within an apartment served by a reverse cycle system can only be provided with either cooling or heating at any one time.

Heat Recovery: Heat recovery system types are not available.

Future Proofing

AC units should be considered for internet connection allowing for:

  • Faults to be emailed
  • Manufacturer connection to review faults
  • Remote app based start/stopping etc.

Ownership & Billing: Refer 1 to 1 Ownership & Billing