MRCOOL Line Set Showdown: 25 ft vs 35 ft vs 50 ft — Which One’s Right for You?

Hey DIY pro-in-the-making 👋 — Samantha here!

So, you’ve decided to install your own MRCOOL DIY mini-split (high-five for that 💪). You’ve got the indoor unit picked out, your condenser ready to go, and maybe even a helper bribed with pizza. But there’s one decision left that can make or break your install:

Which line set length should you choose — 25 ft, 35 ft, or 50 ft?

Let’s break it all down so you can make the perfect pick — no guesswork, no wasted copper, and no kinks.

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1. Why Line Set Length Actually Matters

Your line set is the copper tubing that carries refrigerant between the indoor air handler and outdoor condenser. It’s pre-charged, sealed, and ready to connect.

But here’s the catch — length affects performance and appearance.

• Too short, and you can’t reach the outdoor unit.

• Too long, and you’ll have an awkward coil of tubing and potential efficiency loss.

Think of it like extension cords: you wouldn’t use a 100-footer to plug in a lamp right next to the wall, right?

The EPA’s ENERGY STAR program even notes that proper refrigerant line sizing and routing are key to system efficiency. EnergyStar

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2. The Contenders: 25 ft, 35 ft, and 50 ft

Here’s a quick overview of MRCOOL’s three main DIY line set lengths for 5th Gen systems. All use the same Quick Connect pre-charged design, which means no vacuuming, no refrigerant handling, and no need for an HVAC license.

(Pricing from The Furnace Outlet, subject to change — shop direct below.)

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3. How to Choose Based on Your Layout

The best way to choose a line set is to measure your total run distance — from the indoor unit’s exit point to the outdoor unit’s connection port. Include bends, vertical climbs, and any wall thickness.

🏡 Choose 25 ft if:

• Your indoor and outdoor units are on the same wall.

• The outdoor unit sits directly below or just outside the room.

• Your line route is straightforward (minimal turns).

• You want the most affordable, simplest setup.

This is the “sweet spot” for most single-zone home installs.

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🏠 Choose 35 ft if:

• You’re running lines through an attic, crawlspace, or around corners.

• You’re installing on a second floor with the outdoor unit below.

• You want flexibility without excess slack.

35 ft is the “Goldilocks” option — not too short, not too long — just right for average two-story homes.

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🏢 Choose 50 ft if:

• Your outdoor unit is on the opposite side of the house.

• You’re running through long vertical or horizontal routes.

• You’re connecting to a detached garage, basement, or addition.

• You’re working with a large property or a unique layout.

This is where the MRCOOL 5th Gen 50 ft 1/4” × 1/2” Pre-Charged Lineset shines. It gives maximum flexibility and reach, while still keeping installation DIY-friendly.

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4. Performance & Efficiency Considerations

Line length does more than just affect fit — it influences system performance.

Every additional foot adds a small amount of refrigerant pressure drop and potential energy loss. According to ScienceDirect, “extra line length increases friction loss and heat transfer to the environment, which can reduce system efficiency slightly”. 

That’s why MRCOOL limits its DIY system line length to a maximum of 75 ft total per zone — keeping the balance between flexibility and efficiency.

Shorter runs = slightly better performance, but longer runs = easier placement options. Pick the balance that fits your home’s layout best.

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5. Real-World Scenarios

Here’s how real homeowners typically match lengths to their projects:

No matter the size, MRCOOL’s Quick Connect technology ensures that every option installs easily — just snap, twist, done.

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6. Pricing Sweet Spot 💰

If you’re comparing based purely on value, the 35 ft line set usually hits the pricing sweet spot.

It gives enough flexibility for multi-floor homes without the cost bump of the 50 ft version.

That said, if you’re doing a long run and want peace of mind knowing you won’t come up short, the 50 ft model’s extra cost is well worth it.

Daikin’s installation guidelines note that “having a few extra feet of tubing is better than stretching a line to fit,” which can cause strain on joints and fittings. Daikin

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7. Samantha’s Pro Tips for a Perfect Fit

✨ Tip 1: Measure twice, buy once. Add 10% slack to your total measurement — but don’t overdo it.
✨ Tip 2: Route your line set as directly as possible; gentle bends preserve efficiency.
✨ Tip 3: Always uncoil the line set before installation — it behaves like a stubborn garden hose until it’s stretched out.
✨ Tip 4: For long runs, support the line every 4–6 ft horizontally and 8 ft vertically.
✨ Tip 5: If you’re unsure, go up one size — it’s easier to hide extra length than to add more later.

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8. The MRCOOL Advantage

Regardless of length, all MRCOOL line sets share a few game-changing benefits:

• Pre-charged with R-454B refrigerant — no vacuuming or charging needed.

• Quick Connect fittings — safe, clean, tool-free attachment.

• Insulated and sealed — prevents condensation and protects performance.

• Flexible routing — can be coiled, extended, or rerouted easily.

• DIY-friendly warranty — MRCOOL stands behind their systems when properly installed.

According to MRCOOL’s official specs, each line set undergoes a 400 psi pressure test and 500 lb pull test before leaving the factory, ensuring leak-free reliability.  MRCOOL 

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9. Final Thoughts — Which One Should You Choose?

Here’s the quick cheat sheet:

• 🟢 25 ft → Small, direct installs.

• 🟡 35 ft → Versatile and most common.

• 🔵 50 ft → Long or complex runs, ultimate flexibility.

If you’re working on a single-room or short-run install, go with 25 ft.
If your install spans floors or corners, 35 ft is your sweet spot.
And if your units are far apart — or you just want extra wiggle room — grab the 50 ft and relax knowing you’ve got reach to spare.

Whichever you pick, you’ll get the same MRCOOL ease: no gauges, no pumps, no problem.

Now go ahead — measure your run, click your link, and get ready to snap, twist, done.

In the next blog, you will learn "How to Install Your 50 ft MRCOOL DIY Line Set Like a Pro".