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Question DetailsAsked on 8/20/2016

Mini Split air conditioning inside unit - should the in/out lines be touching?

Daikin mini split ductless air conditioning installed recently, has not been able to adequately cool/dehumidify.
But my main question is, in an effort to resolve/finish installation, the installer removed the individual insulation from each pipe, and wrapped them both together. Won't 10-15 feet of copper pipes at different temperatures touching each other negate the heat exchanging capability?

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1 Answer


You are right - how much effect it will have depends on the particular system operating temps, surrounding air temp, if the bundled lines were then insulated or not. This would, in an ordinary household A/C system, be expected to somewhat cool the supply line to the evaporator, reducing its pressure and therefore reducing the cooling in the coil - mitigated a bit by the fact the incoming refrigerant would be slightly cooler than normal due to the contact, but all in all should be a negative impact. On the return side, the refrigearant would be heated by the incoming line heat transfer, making the return side pressure higher than designed and warmer, which will reduce the efficiency of the compressor and possibly cause overheating as well - another negative.

But running the two lines together will likely cause the system to run at other than optimum conditions because the line temps will not be what the system's control valve is designed for. I would guess if the manufacturer saw this they would say it is not in accordance with their installation instructions, which commonly specify a certain spacing between the lines - or specify they shall be insulated and can then be run in a combined conduit (commonly 3" or 4") along with the drainline. So bundling was probably OK - but not removing the insulation first.

Also - assuming these are copper lines - adjacent metal lines should never touch each other - can cause electrolytic corrosion.

Answered 3 years ago by LCD

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