As part of basement renovation, I am moving the HVAC indoor unit for about 30 feet, which means the refrigerant line has to be extended by same length concealed within basement ceiling.

Now, I have the option of moving the outdoor unit as well to place it closer to the indoor unit's new location. But, this involves additional cost. Am trying to find out if this additional cost is worth moving the outdoor unit.

Would having a lengthy refrigerant line affect AC performance? Would I incur higher utility bill compared to keeping the outdoor unit closer to indoor unit?

My guess is since the coolant travels longer distance, there could be more energy loss, resulting in less cooling in the house causing the AC unit to work harder.

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    The lines are insulated. I'm sure there is some additional loss but it's probably insignificant. – Steve Wellens Jul 17 at 4:36
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    When you run the 30’ pipes use complete long lengths of pipe so there are no jounts hidden in the ceiling - saves grief in the future. I did something similar by buying 20 or 30 metre rolls of pipe and they rolled out easily. – Solar Mike Jul 17 at 7:21

Each manufacturer has installation recommendations for their equipment, including distance, vertical height difference, size of line, etc. I’d follow their directions.

30’ does not seem unreasonable for total length, including distance plus height. See Trane’s installation guide starting on page 18-21.


Obviously when you push the limits of their recommendations, the efficiency will go down.

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  • Standard size insulated A/C line sets come in lengths up to 50" (+or-) so when the HVAC company comes to complete the move they should have the line set they need. The efficiency loss for a longer line set is minimal. – d.george Jul 17 at 10:59
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    You should be fine. Not worth moving the outdoor unit. Remember how AC and heat pumps work: The main method of moving heat is condensation and evaporation, which occurs in the outdoor unit and the air handler. You're not moving actual heat like a hydronic system or air in ducted system. – George Anderson Jul 17 at 13:01

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