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Required Size of line sets

Posted by RobNo (My Page) on
Tue, Mar 22, 11 at 15:01

I am looking to install a new AC and furnace. I am getting conflicting information about the correct size of the line set. One contractor said that for a 5 ton unit, a 1 1/8" line set is required or else the warranty could be voided. Another contractor said what i currently have, which I believe is a 3/4" is fine, and they will flush, vacuum, and pressure check the lines. I am considering a Carrier 16 SEER vs a Lennox 16 SEER. Also, one said 4 ton is the right size, and the other said 5 ton. One I know did a load calc, and the other said he did, but I do't recall him actually doing it. Will have second one do another load calc to be sure his measurements are correct. Words of advice?

Follow-Up Postings:

RE: Required Size of line sets

The size of the outdoor unit, and also the length of the line set run, both factor into the proper size.

It would big a big mistake to not have the correct size, as the are important reasons why either too big or too constrictive a size would be a problem.

Ask the dealer ( or try yourself with google) to get the tech guide for your unit and verify the correct size of the lines (there are 2 in the set-- liquid and suction )

And IMHO, it is always better to put in a new line set if you are able, as you don't need to worry about flushing the old or getting hydroscopic oil in the new R410a refrigerant.

That's my free advice

RE: Required Size of line sets


thank you for the info. are you aware of the manufacturer voiding a warranty because the line set is not the correct size/too small?

RE: Required Size of line sets

I have the product document for my Carrier condernser (24ana7). It shows the vapor line for a 5 ton unit should be 1 1/8 in. for the outside diameter. This is for a line up to 80 feet in length. For longer lengths the diameter may need to be larger.

You always run the risk of voiding the warranty if you not follow the instructions of the manufacturer. It is an easy excuse for the manufacturer to not pay a warranty claim.

If you are moving from an R-22 to an R-410, then the best advice is to replace the line set and install the size listed in the installation manual.

RE: Required Size of line sets

fantastic. thanks for the info

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