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I have one Hitachi i-clean split AC 2ton unit installed in my home. I want to connect another indoor ductless unit to the already installed outdoor compressor. I only need to use one indoor unit at a time. How do I connect two indoor units to a single compressor - is this possible?

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It's certainly possible (I've seen it done) though it might help to know the exact model number of the compressor you have to determine if it's possible with this unit. Also I don't really think this is a DIY job unfortunately. –  Steven Apr 28 '12 at 15:17
    
ya know...for mild climates, this is an option I had never considered...splitting one compressor between two heads with only one used at once. I imagine this would be most doable with some electronic set up where it wouldn't allow both to be run at once. –  DA01 Apr 28 '12 at 15:22
    
I noticed before you're question was edited you said you are going to install .... Unit have you already or just looking? You can buy dual head units made for the specific purpose you want. –  UNECS Apr 30 '12 at 7:07
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The capacity of the unit is obviously a concern. A compressor designed for one indoor unit is not likely to work as well with two. I know you've said that you are only going to use one at a time, but you should also consider what to do when you resell the house. A home inspection may pick up on that, and a smart buyer will want that to be fixed (either by subtracting money or getting you to buy a new unit). –  gregmac Apr 30 '12 at 18:14

4 Answers 4

It can but you must modify the circuit to protect from operating both of them at same time by the following:

  • You need to install two T connections at the IN/OUT of compressor.

  • Modify the compressor protection by adding relive valve to bypass the pressure upon increasing pressure.

  • Use two solenoid valves each one at the O/P T tube which will feed the Indoor unit.

Solenoid valves will be feed power from O/P terminal in indoor unite which assigned to feed out door unit and add relay protection to prevent both solenoid open.

Remember if you are feeding the the two indoor unit from different power source so you must install relay or contractor which will feed the Compressor from independent power source or direct.

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Yes it's possible. If you really do use only 1 at a time, this piping (tee it in where possible) will work. Only 1 terminal will work at a time and the condenser will only see 1 indoor coil (the load).

If you use more than 1 terminal at a time, then it depends if the outdoor unit (outdoor compressor) can meet the demand (indoor coils). A 2-ton outdoor unit will give you a little more than 2-tons when more than 1 terminal unit is operating but there is a limit.

Each manufacturer can be different regarding how to wire in the additional thermostat. Check with a rep to find out the exact Tstat wiring (i.e., the inclusion of another indoor unit) and Tstat programming.

Good Luck!

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The outdoor unit needs to have a control board that allows for more than on indoor unit to hook to. At minimal you would need to changed the board unless it already has it in it, which is not common. Then the system must have separate valves for each indoor unit so to prevent refrigerant flowing to the unit not being used.

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If his house is relatively new and well insulated and not too enormous (1500 SF or less) and not in a very hot area, two tons is probably enough for the whole house most of the time. I've got 2.25 tons downstairs and 2.5 tons upstairs in a 3200 SF house and it's always been more than enough so 2 tons for 1500 SF or less is probably fine even if you run both evaporators at once.

However, I would want to be sure that you could switch off one of the two evaporators because that seems essential to his planned usage. It could be for energy savings or just because he already knows 2 tons isn't enough for the entire house, he doesn't say.

The actual question of connecting two evaporators to one condensor is quite easy, you just need to add a T to the freon supply and a T to the freon return. But how will the compressor be told to turn on? You don't want the room with the evaporator you are not using to run the compressor.

And how do you stop freon from going to the evaporator you are not using?

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