Heating, Air Conditioning, Fridge, HVAC/ac lineset sizing


Due to noise issues, we are moving a 4-ton Trane unit farther away from the house - about 80' from compressor to air handler.
My installer recommends using 1 1/8" for the suction line, and says 3/8 is OK for the pressure line.  Another installer (a friend) says to go with 1/2" when using 1 1/8.
What do you say?


Here's Trane's Application Guide #APP-APG006-EN.

You didn't say what refrigerant the system uses, or whether it's single or two stage. I've assumed R410A single stage.

1-1/8" suction lines are only permitted on 4 ton AC systems, prohibited on 4 ton heat pump systems (Table 3, footnote 3). Having said that, the 7/8" losses are negligible (2% at 140 feet), and oil return would be better with the smaller size. 1/2" looks good for the liquid.



PS: Follow Trane's recommendations for "sleeving" underground tubing, don't just bury the tubing in the ground; and don't permit any inaccessible joints.

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Fred Weldin


I can't help you if your whatsis won't work, people (Especially if it's a refrigerator); I have no experience with appliances, and I haven't been involved with H&AC service and repair since March 08, 1996 (Thank the Lord); I always send a "standard" reply to appliance questions and H&AC "Service and Repair" questions (about 20 a month), so if you want to know why your whatsis isn't working like it used to, ask someone else. A lot of my answers arenít read by the questioners; in that event, I always send reminders to read the answers for a month or more (the word "idiots" comes to mind - actually there's another more appropriate word, but discretion prevents its use here). If you have questions about how big a unit you need, if one room's warmer than the others, if you want an opinion oas to scope of work on bids received, etc. just ask. Do visit www.askweldin.com, there's a lot of good information on sizing, ductwork, efficiency, as well as some techniques accomplished DIY-ers can use to troubleshoot and improve their H&AC. Finally, I want to thank all of the kind, serious people whom I meet here: I enjoy working with you. My wife says I'm "snarky" from time to time; as for you others, please use your imagination as to the responses swirling on the snarky side of my brain when I read your questions.


53 years in the business. See www.askweldin.com


B of ME U of D 1965, numerous classes, seminars and a lot of "Hands On" learning since.

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