Split A/C Piping

[mecheng2001ca]

Is there a rule of thumb for the maximum distance that you can locate the condensing unit from the indoor unit?

Thanks

[joeseffus]

There is no rule of thumb for a distance.
Each manufacturer has different capabilities for different distances.
For example a Carrier HDC condensing unit can be placed up to 200 equivalent feet horizontally from the evaporator.
A similar product manufacturer by Sanyo can only be about 65 equivalent feet.

I say equivalent feet because the piping most likely is not a straight run and you have to take into account the minor losses, elbows, fittings, etc.

Also, please note that this is not without capacity loss. The system rated at 36000 Btu/hr will not provide 36,000 Btu/hr of cooling at this distance.

Another problem is vertical distance. Carrier suggests to stay below 65' vertically.
Liebert says they can go further vertically, but you have to size the piping appropriately.
If you undersize the piping the refrigerant could exceed a certain velocity that will allow the oil and refrigerant to seperate, and your compressor doesn't get oiled. On the other hand if you have too large piping the suction line could begin to condense in the vertical rise, so they suggest to trap the suction line every 20' or so...

Really, I would suggest to read through the manufacturer's literature because each condensing unit is different.

[jimgpe]

Could not have said it better.

Refrigerant piping design, especially under long-run or long-riser conditions, takes some experience. At risk is the compressor. You need to do it right the first time, or your only option (after 4 "in warranty" compressor replacements) will be do tear it out and do it right the second time.

Get the manufacturer to sign off on an isometric sketch showing each elbow, trap, pipe size, rise, fall, etc., and the length of each piece.