When setting up your MRCOOL DIY mini split system, one of the most critical decisions is selecting the correct lineset length. Linesets connect the outdoor condenser to the indoor air handlers, and getting the right length can mean the difference between a hassle-free installation and a costly, inefficient one. For many homeowners, the 35ft MRCOOL 5th Gen Pre-Charged Lineset (Model DIY35-1412C) strikes the perfect balance—but how do you know it's right for your project?
In this guide, we’ll explore everything you need to know about selecting the proper lineset length, what the 35ft model offers, and when it makes sense (or doesn’t) for your home setup.
🏛️ What Is a Lineset and Why Does Length Matter?
A lineset consists of two insulated copper tubes—a liquid line and a suction line—that carry refrigerant between the indoor and outdoor components of your mini split system.
Length matters for several reasons:
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Cooling Efficiency: A lineset that is too long or too short can impact the system's cooling or heating performance.
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Ease of Installation: Proper length ensures a clean, code-compliant, and frustration-free install.
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Refrigerant Flow: MRCOOL DIY linesets are pre-charged with R-410A refrigerant, and their sealed design depends on matching length specs.
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No-Vac Technology: One of MRCOOL’s standout features is eliminating the need for vacuuming lines. But this only works if the correct pre-charged lineset length is used.
🛍️ Understanding the DIY35-1412C: Specs That Matter
The MRCOOL DIY35-1412C Lineset is part of the 5th generation pre-charged lineup and includes:
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Length: 35 feet
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Fittings: 1/4" liquid and 1/2" suction line diameter
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Refrigerant: Factory sealed and pre-charged with R-410A
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Insulation: Extra-thick UV and weather-resistant foam
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Connectors: Quick-connect fittings for tool-free installation
These linesets are designed to be plug-and-play with MRCOOL DIY mini split systems
🏡 Measuring Your Distance: How to Estimate Properly
To determine whether a 35ft lineset is right for your setup, follow these steps:
✅ Step 1: Identify Equipment Placement
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Outdoor condenser location: Ground mount, wall bracket, or rooftop.
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Indoor air handler location: Wall height, distance between floors, and wall thickness.
✅ Step 2: Map the Route
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Measure horizontal and vertical distances.
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Account for obstructions like corners, walls, or joists.
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Add length for slack and drip loops.
✅ Step 3: Consider Bends and Coiling
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MRCOOL linesets should not be sharply bent or kinked.
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Extra footage is needed for gentle bends and wall penetrations.
⚠️ Pro Tip: Add 10% buffer to your total distance to avoid coming up short. It’s better to have extra to coil than to stretch the line.
Useful Tools
🌐 When 35ft Is Ideal: Common Use Cases
The 35ft lineset is a great fit for many home installations:
🏠 Single-Story Homes
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Outdoor unit mounted on the rear or side of the house
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Indoor unit on an opposite wall or across a basement crawl space
↕️ Multi-Story Homes
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Condenser on the ground
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Indoor unit on a second-floor room
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Routes through attics, garages, or wall cavities
🏢 Detached Structures
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Garage, shed, or ADU installs
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Condenser near house, air handler across a yard or wall
🔹 Mid-Zone Routing
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Want to hide the line in soffits or chase runs
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A little extra length allows more routing options
❌ When 35ft Might Be Overkill (Or Too Short)
There are cases where the 35ft MRCOOL lineset might not be a good fit:
❎ Too Long: Wasted Line & Installation Hassle
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If your route is only 15–20 feet, a 16ft or 25ft line is cleaner.
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Excess coiling can create unsightly bulges and stress on connectors.
❎ Too Short: Performance Issues
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If you under-measure and need 40–45 feet, you're stuck.
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MRCOOL allows line set extensions using couplers but adds cost and potential leak points.
Explore MRCOOL coupler kits here.
🪜 Matching Lineset Length to BTU Capacity
While length matters physically, it also matters thermodynamically. The longer the lineset, the more resistance and refrigerant volume required.
MRCOOL Guidelines
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Under 24,000 BTUs: stick to 16–25ft lines
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24,000–36,000 BTUs: 25–35ft ideal
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48,000 BTUs and above: consider 35ft+ or extensions
Refer to the official MRCOOL Installation Manuals for BTU-specific recommendations.
🧹 Installation Best Practices for a 35ft Lineset
✅ Secure Support
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Use pipe clamps or brackets every 4–6 feet
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Prevent sagging that can stress fittings
✅ Gentle Bends Only
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Minimum bend radius of 5" recommended
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Use line benders or guides if needed
✅ Keep It Dry & Cool
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Avoid running lineset in direct sunlight or near hot appliances
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Use line set cover kits for UV protection
✅ Connect Carefully
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Align quick-connect fittings
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Tighten with a torque wrench to MRCOOL specs (usually 33–35 ft-lbs)
🌟 Alternatives: Other Line Set Lengths Available
MRCOOL DIY linesets come in various lengths:
| Length | Model | Best Use Case |
|---|---|---|
| 16ft | DIY16-1412C | Short runs or wall-mounted units |
| 25ft | DIY25-1412C | Average bedroom or office installs |
| 35ft | DIY35-1412C | Multi-level, detached structures |
| 50ft | DIY50-1412C | Large homes or long attic routes |
⚡ Final Thoughts: Is the 35ft Lineset Right for You?
If your route is over 25 feet and under 40, the MRCOOL 35ft DIY lineset offers the best of both worlds: enough length for vertical and horizontal freedom without needing extensions, and an easy-to-use pre-charged setup.
But don’t guess.
Measure twice.
Map your route.
Read your BTU specs.
And remember: just because it’s pre-charged doesn’t mean one-size-fits-all.
In the next topic we will know more about: What Makes the MRCOOL DIY35-1412C Pre-Charged Line Set Different?
