Normal split unit:


Ducted split unit:

enter image description here

I have:

  • Outdoor split unit that compresses gas.
  • Compressed gas moves down to some room where it connects to some wall-mounted indoor split unit.
  • The indoor split unit returns uncompressed gas up to the outdoor unit.
  • Both the outdoor and the indoor units are made by the same vendor.


  • What's the cheapest way to transform the split unit into a ducted split unit?


  • Can I keep the outdoor compressor unit, and only replace the wall-mounted split unit by a false-ceiling unit?
  • $\begingroup$ You're on an international site and I've never heard of a "split unit" so you should edit to explain what it means. It may be specific to your location. In any case this sounds like a question for diy.stackexchange.com, not Engineering. $\endgroup$
    – Transistor
    Aug 4 at 19:31
  • $\begingroup$ Done. Done. Done. $\endgroup$
    – caveman
    Aug 4 at 19:50
  • $\begingroup$ The cheapest way is probably to put the device inside your duct and duct tape a return air duct into the device. The cheapest way to do it right is to buy a unit designed for what you want to do. $\endgroup$
    – Tiger Guy
    Aug 6 at 20:53
  • $\begingroup$ What do you mean "ducted split unit" - to use 1 unit for multi rooms, or just hide the indoor unit in the wall or ceiling? And what "head" to remove? It is not clear to me what you are intended to do $\endgroup$
    – r13
    Sep 7 at 17:33

You need to install a new coil and a metering valve in the false ceiling complete with a plenum and a fan to recycle the air. And all this has to be scaled with your condenser (you call it compressor) not too big, not too small. Got to be careful to put the right amount of "freon" when you charge the system.

you need to calculate your system and know exactly what you are doing and have the right tools.

In the US only people with proper licenses can buy and dispose of refrigerant because of climate concerns. They have to log everything.

  • $\begingroup$ What's a coil? ? $\endgroup$
    – caveman
    Aug 8 at 6:58

Coil is usually a cube of packed fins of aluminum with a thin copper pipe going back and forth through it.

Similar to a car radiator. it allows the coolant to evaporate and extract the heat it needs for evaporation from the fins.

Hence the air pushed by the fan passing through the fins of the coil gets cold.

evaporative coil.


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