Line Set Charge Calculator
Work out how much refrigerant to add for a line set longer than the factory-charged length.
How to use ↓Always follow the unit’s install manual and nameplate. Rates and factory-charged lengths change by brand, model and refrigerant. The manual for the unit you are installing wins over this page.
A2L refrigerant (mildly flammable). R-454B and R-32 are A2L refrigerants.
- Only work on A2L systems if you’re properly trained in handling these refrigerants.
- Use tools rated for A2L refrigerants: recovery machine, gauges and a leak detector designed for the refrigerant (non-sparking).
- Keep ignition sources away from the work area: no open flames, smoking or operating heaters.
- Follow the install manual’s minimum room area (TAmin), charge limits and refrigerant leak sensor requirements.
- Added line set charge counts toward the total system charge. It can push the total past the room-area limit for the space.
Sources: Lennox 508747-01 (total charge = factory + field-added charge; TAmin table), Lennox 508443-01 (ignition sources, non-sparking leak detection, sensor), Carrier LLG-R454B-01 (equipment and leak detectors designed for R-454B).
One-way length of the liquid line.
Usually 15 ft on ducted splits; often 25 ft or more on ductless.
Enter the total line set length.
How to use
- Pick the refrigerant and the liquid line size. The table rate fills in.
- Measure the one-way line set length, service valve to indoor coil.
- Check the factory-charged length and the rate in the install manual. Change them if your unit is different.
- Weigh in the result, then finish the charge by subcooling or superheat per the charging chart.
How it works
Additional charge (oz) = (total line length − factory-charged length) × oz per foot. If the line set is shorter than the factory-charged length, the calculator shows 0. Some manufacturers (for example Carrier and Lennox) say to remove charge at the same rate below 15 ft, and Trane sets the adder to 0. Follow the manual.
Carrier/Rheem method: some manuals base the factory charge on 15 ft of 3/8 in line (9 oz): additional oz = (rate × total length) − 9 oz, shown as 0 if negative (those manuals say to remove the difference). Carrier’s R-454B long-line guide and Rheem *AGN use it. It matches the standard method for 3/8 in line but differs for 1/4, 5/16 and 1/2 in. Example from Carrier: 45 ft of 5/16 in R-454B = 0.40 × 45 − 9 = 9 oz. The calculator picks this method for R-454B; switch it in Step 6.
R-454B and R-32 are A2L (mildly flammable). The total charge, factory plus added, sets the minimum room area in the manual. Check it before adding charge.
Mitsubishi tables use the one-way piping length; do not double it for the two lines. 1 oz/ft = 93.01 g/m.
Rates from install manuals
Every figure below was read in the linked manufacturer document. Rates for other models can differ.
| Brand | Refrigerant | Liquid line | oz/ft | Factory length | Document | Source |
|---|---|---|---|---|---|---|
| Rheem/Ruud | R-410A | 1/4 in | 0.3 | 15 ft | (-)ARL-JEZ / (-)ASL-JEZ condensing units installation instructions | resource.gemaire.com |
| Rheem/Ruud | R-410A | 5/16 in | 0.4 | 15 ft | (-)ARL-JEZ / (-)ASL-JEZ condensing units installation instructions | resource.gemaire.com |
| Rheem/Ruud | R-410A | 3/8 in | 0.6 | 15 ft | (-)ARL-JEZ / (-)ASL-JEZ condensing units installation instructions | resource.gemaire.com |
| Rheem/Ruud | R-410A | 1/2 in | 1.2 | 15 ft | (-)ARL-JEZ / (-)ASL-JEZ condensing units installation instructions | resource.gemaire.com |
| Rheem/Ruud | R-410A | 1/4 in | 0.3 | 15 ft | *AGN series R410A condensing units installation instructions | files.myrheem.com |
| Rheem/Ruud | R-410A | 5/16 in | 0.4 | 15 ft | *AGN series R410A condensing units installation instructions | files.myrheem.com |
| Rheem/Ruud | R-410A | 3/8 in | 0.6 | 15 ft | *AGN series R410A condensing units installation instructions | files.myrheem.com |
| Rheem/Ruud | R-410A | 1/2 in | 1.2 | 15 ft | *AGN series R410A condensing units installation instructions | files.myrheem.com |
| Carrier | R-410A | 3/8 in | 0.6 | 15 ft | 598B two-speed Puron (R-410A) AC installation and start-up instructions | shareddocs.com |
| Carrier | R-454B | 1/4 in | 0.27 | 15 ft | Residential Piping and Long Line Guideline R-454B (LLG-R454B-01) | shareddocs.com |
| Carrier | R-454B | 5/16 in | 0.40 | 15 ft | Residential Piping and Long Line Guideline R-454B (LLG-R454B-01) | shareddocs.com |
| Carrier | R-454B | 3/8 in | 0.60 | 15 ft | Residential Piping and Long Line Guideline R-454B (LLG-R454B-01) | shareddocs.com |
| Trane | R-410A | 5/16 in | 0.4 | 15 ft | 16 SEER AC/HP installation instructions (J4HP6) | tranetechnologies.com |
| Trane | R-410A | 3/8 in | 0.6 | 15 ft | 16 SEER AC/HP installation instructions (J4HP6) | tranetechnologies.com |
| Trane | R-410A | 1/2 in | 1.2 | 15 ft | 16 SEER AC/HP installation instructions (J4HP6) | tranetechnologies.com |
| Trane | R-410A | 3/8 in | 0.6 | 15 ft | 4TTR7 condensing units installer's guide (18-AC94D1-4-EN) | trane.com |
| Goodman/Daikin | R-410A | 3/8 in | 0.6 | 15 ft | Long Line Set Application R-410A (TP-107O) | mobile.goodmanmfg.com |
| Daikin | R-410A | 3/8 in | 0.60 | 15 ft | DX series Long Line Set Application R-410A (TP-107M) | daikincomfort.com |
| Lennox | R-454B | 3/8 in | 0.6 | 15 ft | EL21KLV installation instructions (R-454B) | manualslib.com |
| Mitsubishi Electric | R-410A | 1/4 in | 0.216 | 25 ft | MUZ-FS06-18NA(H) service manual OBH873B | meiersupply.com |
| Mitsubishi Electric | R-410A | 3/8 in | 0.592 | 33 ft | MUZ-GL24NA service manual OBH733F | totalcomfortmech.com |
| Fujitsu | R-410A | 1/4 in | 0.2 | 49 (09/12) or 66 (18) ft | ASU9/12/18 RLS-type (09LUAS1C) installation manual | hvacdirect.com |
| Daikin | R-32 | 1/4 in | 0.22 | 49.25 ft | 19 Series FTXF/FTKF09-12BVJU9 specifications | Daikin spec sheet FTXF09BVJU9-SPC (PDF) |
| York | R-454B | 3/8 in | 0.57 | 15 ft | YH6 R-454B heat pump tech guide YH618/624/630/636E2S11 (3/4 vapor) | yorknow.com |
| York | R-454B | 3/8 in | 0.60 | 15 ft | YH6 R-454B heat pump tech guide YH648E2S11 (7/8 vapor) | yorknow.com |
| York | R-454B | 3/8 in | 0.67 | 15 ft | YH6 R-454B heat pump tech guide YH660E2S11 (1-1/8 vapor) | yorknow.com |
Not verified, so not in the table: R-454B 1/2 in (York R-454B rates shown are all 3/8 in liquid and vary by model), R-32 ducted splits (Goodman GLXS manual could not be opened), Fujitsu and Mitsubishi R-454B/R-32 models.
FAQ
What is the typical factory-charged length?
15 ft on most ducted split systems (Carrier, Trane, Goodman, Daikin, Lennox, Rheem). Ductless units vary: 25 ft on many Mitsubishi models, 49 ft on some Fujitsu and Daikin models.
Does the suction line need extra charge?
Mostly no; the rate is for the liquid line. Daikin’s long-line guide gives slightly higher rates for big suction lines (0.63 to 0.78 oz/ft with 3/8 in liquid).
Is the weighed-in amount the final charge?
No. It is the starting point. Finish with the subcooling or superheat target from the unit’s charging chart.