SettingsSettings for this calculationUS
The tape-measured length of pipe on the route, ignoring the fittings for now.
Measure the route you will actually run, not the straight line between the units. Sags, the drop down a riser and the loop round a beam are all real pipe. Where the route is not yet fixed, measure the longest option you might be forced into.
Count of 90° direction changes made with a long-radius bend or a bending spring.
A swept bend costs a third less than a pressed short-radius fitting for the same turn, which is the cheapest saving on a marginal route. Count bends you make in the tube as long radius provided the tube did not kink.
Count of 90° direction changes made with a pressed or wrought short-radius elbow.
These are the fittings out of the box — tight, convenient at a wall penetration, and half again as costly in equivalent length as a swept bend of the same size.
Count of oil traps formed in the suction line, at the base of risers and at intervals up them.
Each trap is counted as four 90° bends here, which is how one is made. Traps are not optional on a riser — they are what returns oil to the compressor — but they are expensive in equivalent length, and that cost is the argument for keeping the riser short rather than for leaving traps out.
The bore of the line being assessed — normally the suction line, which governs.
ACR tube is sold by outside diameter, so subtract twice the wall thickness: 7/8 in OD with a 0.030 in wall has a 0.815 in bore, about 20.7 mm. Assess the suction line, since it carries the vapour and dominates the pressure drop; the liquid line is checked separately against subcooling.
The equivalent lengths your valves, drier and any accessories are published at, added together.
This calculator does not supply these numbers and will not guess them. A filter-drier's resistance is a property of that drier and its core; a ball-type service valve is nearly free while an angle valve is not. Take each figure from its own data sheet, add them, and enter the total. Leave it at zero only if you genuinely have none of these on the route.
The limit printed in the installation instructions for this exact model.
Read it off the model's own document, not off the range brochure. Manufacturers state this either as a total equivalent length or as a straight length with a separate fitting allowance, and the two are not interchangeable — if yours states a straight length plus a fitting count, your limit for this page is the straight figure.
Total equivalent line length
104.8 ft
- Straight run measured
- 82 ft
- Equivalent length added by bends and traps
- 16.25 ft
- Component allowance entered
- 6.5 ft
- Remaining allowance against the published maximum
- 45.25 ft
- Share of the published maximum used
- 69.83 %
They open the calculator with your figures already in it
Refrigerant Line Total Equivalent Length Calculator: 105 ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- ASHRAE Handbook — Refrigeration, System Practices for Halocarbon Refrigerants: a route is assessed as total equivalent length, the measured straight run plus the straight-pipe length each fitting is worth, and that total is what the equipment's published maximum limits
- Crane Technical Paper No. 410, Flow of Fluids Through Valves, Fittings and Pipe — equivalent length expressed as a multiple of inside diameter: L/D = 20 for a long-radius 90° bend, L/D = 30 for a short-radius one. A trap is counted as four 90° bends, which is its geometry rather than a coefficient
- Service valve and filter-drier allowances are NOT supplied by this calculator. They are entered from the component's own data sheet, because a drier's pressure drop is a property of that drier and no generic figure for it would be honest
- Distinct from this site's Pipe Fitting Equivalent Length Calculator, which totals only the fittings in a hydronic run from equivalent lengths the user already holds. This one adds the measured straight length, counts refrigeration-specific components, and reports the result against the equipment's published limit
Inputs used
- Measured Straight Line Length
- 82 ft
- Number of Long-Radius 90° Bends
- 4
- Number of Short-Radius 90° Elbows
- 2
- Number of Suction Traps
- 1
- Line Inside Diameter
- 0.75 in
- Service Valve and Filter-Drier Allowance
- 6.5 ft
- Model's Published Maximum Equivalent Length
- 150 ft
Intermediate steps
- Straight run measured
- 82 ft
- Equivalent length added by bends and traps
- 16.25 ft
- Component allowance entered
- 6.5 ft
- Remaining allowance against the published maximum
- 45.25 ft
- Share of the published maximum used
- 69.83 %
What this calculation does not cover
- Equivalent length is a pressure-drop argument. It says nothing about vertical separation, which is a separate limit on most models and is governed by oil return rather than by friction.
- The L/D ratios describe geometry, not refrigerant. Where a manufacturer publishes its own per-fitting allowances for the model in front of you, those are the figures to use.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-08-30 · in the site-wide review of 2026-09-06 · v1.0.0
Regulatory standards & verification citations4
- ASHRAE Handbook — Refrigeration, System Practices for Halocarbon Refrigerants: a route is assessed as total equivalent length, the measured straight run plus the straight-pipe length each fitting is worth, and that total is what the equipment's published maximum limits
- Crane Technical Paper No. 410, Flow of Fluids Through Valves, Fittings and Pipe — equivalent length expressed as a multiple of inside diameter: L/D = 20 for a long-radius 90° bend, L/D = 30 for a short-radius one. A trap is counted as four 90° bends, which is its geometry rather than a coefficient
- Service valve and filter-drier allowances are NOT supplied by this calculator. They are entered from the component's own data sheet, because a drier's pressure drop is a property of that drier and no generic figure for it would be honest
- Distinct from this site's Pipe Fitting Equivalent Length Calculator, which totals only the fittings in a hydronic run from equivalent lengths the user already holds. This one adds the measured straight length, counts refrigeration-specific components, and reports the result against the equipment's published limit
Cite this page
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