Factors to consider when choosing a position for your indoor and outdoor unit

Image by Max Rahubovskiy

Positioning of both the indoor and outdoor units of a mini-split system usually involves compromises. Consider the following in your planning:

Indoor unit

  • The pipe run between the indoor and outdoor units
    Shorter = more efficient. Note that pre-charged mini-split systems usually have a minimum as well as a maximum distance for the pipework. Sometimes additional refrigerant is required for longer runs - check the specifications. Also consider the position of the hole in the wall and any structural implications.
  • A downward flow for the condensate pipe
    In a mini-split system the condensate pipe is usually a 16mm pipe that needs to be ducted outside to a drain or soakaway. A continual downward flow (even if only slight) is preferred. If there are any upward slopes a condensate pump will have to be fitted, increasing complexity, cost, and increasing likelihood of water leakage in the event of issues.
  • Position away from internal heat sources
    Including radiators, ‘fridges, TVs, and where possible south facing windows.
  • A central location
    High on the wall (2m - 2.5m) with good air-flow so the hot or cool air can move freely.
  • Appearance
    Some manufacturers offer indoor units that are much more visually acceptable. If appearance is a concern, this can be the deciding factor between manufacturers.

Outdoor unit

  • Planning and noise
    See the separate ‘Planning permission’ and ‘Noise and neighbours’ pages.
  • Electrical supply
    How power will reach the unit and power isolator position. See ‘Electricity supply’.
  • Wall / ground mounted
    Wall mounted is often easier because lying water and flooding issues can be avoided. However, for wooden structures such as cabins, wall strength and vibration must be considered. Ground stands require preparation or paving.
  • Condensate
    Many units which offer both heating and cooling have condensate outlets on both the internal and external unit. How the condensate water drains to has to be considered.
  • Ease and length of pipe run and height differential
    Manufacturers give information on the maximum height differential between indoor and outdoor units, as well as minimum and maximum pipe runs. Check the specifications before buying a unit.
  • Ventilation, sunlight and heat
    Good ventilation helps the unit capture or dissipate heat more effectively. Direct sunlight and heat can make cooling less efficient.
  • Safety and maintenance
    Ensure the pipe and cable runs and proposed position are not hazardous to others, but can also be easily accessed for maintenance.
  • Trees, shrubs and plants
    The outdoor unit will blow hot and cold air depending on whether it is heating or cooling. This could have a detrimental effect on trees and plant life. However, well positioned plants can help disguise an outdoor unit!

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