Thread: Calculating Freon with Longer coper lines

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I am installing a 25 ton condenser , it already has a freon charge but for only 15 feet of lines.I am running 30 feet of lines, what method should I use to calculate the additional freon need (aside from Super heat/Supper cool method.

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Correction that's 2.5 tons

3. What size liquid line? Add .6 oz per foot for 3/8. Of course you read that in the instructions.

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i always end up with "supper cool" when i work late.

5. This is the only method...

6. Unless you have exact capacity data on the indoor coil and the lineset "AND" the outdoor unit has a precise charge in it "AND" there are no variables such as filter/driers added to the system, you are best to adjust the refrigerant to proper superheat or subcool depending on the systems metering.

Even if you are perfect on the weigh in charge, the air flow of the indoor and outdoor units must both be exactly as specified for the system to be operating at it's optimum.

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Take your sub cool reading on 22 take 68 to 70 reading on low side of gage

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Originally posted by dancsurf
I am installing a 25 ton condenser , it already has a freon charge but for only 15 feet of lines.I am running 30 feet of lines, what method should I use to calculate the additional freon need (aside from Super heat/Supper cool method.

First Step is to know the exact ammount of refrigerant you have on that system and add refrigerant by the manufacturers instructions table (to compensate for the extra lineset). If you don't have that info 100% correct, the only way to charge it properly is by using SH (fixed metering) / SC (TXV metering) method.

Hope this help.

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