When it comes to installing a MRCOOL DIY mini split system, choosing the correct pre-charged line set is just as important as selecting the air handler or condenser. One of the most popular options, the MRCOOL DIY35-1412C, offers 35 feet of pre-charged copper tubing and promises a no-vacuum, no-special-tools-required installation. But the real question is: is it compatible with your system?
In this guide, we’ll break down which MRCOOL models pair perfectly with this line set, how to verify fit, and when you might need an alternative or an extension.
🔧 DIY35-1412C Quick Specs: What You’re Working With
Let’s start with the basics. The MRCOOL DIY35-1412C is part of the 5th generation MRCOOL product family. Here’s what you get:
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Length: 35 feet
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Liquid Line Size: 1/4"
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Suction Line Size: 1/2"
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Pre-Charged Refrigerant: R-410A
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Connectors: Quick-connect, no tools needed
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Insulation: UV-protected, pre-wrapped foam
It’s made for systems that use 1/4" liquid and 1/2" suction lines and need about 30–40 feet of reach between the indoor and outdoor units.
📄 MRCOOL Systems That ARE Compatible with the DIY35-1412C
This lineset is tailor-made for many mid- to high-capacity MRCOOL DIY systems. If your system meets the following specs, you're in good shape.
🏡 Single-Zone Systems
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DIY-24-HP-230B25 (24,000 BTU)
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DIY-36-HP-230B25 (36,000 BTU)
📊 Multi-Zone Systems
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DIY-MULTI3-27HP230 (27,000 BTU 3-Zone)
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DIY-MULTI3-36HP230 (36,000 BTU 3-Zone)
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DIY-MULTI4-48HP230 (48,000 BTU 4-Zone)
🏢 Compatible Indoor Air Handlers
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DIY12-HP-WMAH-230B (12k BTU)
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DIY18-HP-WMAH-230B (18k BTU)
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DIY24-HP-WMAH-230B (24k BTU)
These units all use 1/4" x 1/2" line sets and are within the refrigerant capacity range for a 35ft pre-charged setup.
📌 Confirm with the MRCOOL Compatibility Tool for your specific model.
📅 Systems That Are NOT Compatible
Some MRCOOL models use different suction line sizes or BTU capacities that don’t pair well with this lineset.
❌ Not Compatible With:
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DIY-09-HP-WMAH-115B (9k BTU air handler – uses 3/8" suction line)
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DIY-12-HP-WMAH-115B (older 12k model with 3/8" suction line)
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Any systems requiring 3/8" x 1/4" linesets (e.g. DIY35-1438C)
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Legacy or 3rd/4th Gen MRCOOL units with non-quick-connect setups
🛠️ You can’t force a 1/2" connection onto a 3/8" unit. Always match by manufacturer spec.
🤔 How to Know Which Lineset You Need
Step 1: Find Your Model Number
Look at the label on your outdoor condenser or indoor handler. You’ll see a model number like DIY36HP230C00 or DIY18HPWMAH230B.
Step 2: Identify Line Set Sizing
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Cross-reference your model on the MRCOOL Product Page
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Look for suction line and liquid line dimensions
Step 3: Measure Total Distance
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Estimate total feet from condenser to air handler
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Add bends, slack, and wall penetrations
If your distance is between 30 and 40 feet, the DIY35-1412C will likely be the best choice.
🛏️ Using Coupler Kits to Extend Length
What if 35ft isn’t long enough? You don’t need to swap the lineset—just extend it with MRCOOL’s DIY Coupler Kit.
How It Works
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Connect two pre-charged MRCOOL linesets end-to-end
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Use MRCOOL-approved coupler with sealed valve system
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Maintain refrigerant integrity across connection
Common Extension Combos:
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35ft + 16ft = 51ft
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35ft + 25ft = 60ft
📈 Max recommended length: Check your BTU rating and MRCOOL’s install manual for limits (usually 75ft or less).
🚼 Sizing Table: BTU vs. Line Set Compatibility
| BTU Rating | Suction Line | Liquid Line | Use DIY35-1412C? |
|---|---|---|---|
| 9,000 | 3/8" | 1/4" | ❌ No |
| 12,000 | 1/2" | 1/4" | ✅ Yes |
| 18,000 | 1/2" | 1/4" | ✅ Yes |
| 24,000 | 1/2" | 1/4" | ✅ Yes |
| 36,000 | 1/2" | 1/4" | ✅ Yes |
Always verify both line size and length requirements before purchase.
❌ Common Mistakes to Avoid
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Forcing incompatible sizes: Never attempt to use reducers or clamps
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Guessing the distance: Use a tape or laser measure for accuracy
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Skipping coupler kits: Don’t try to splice linesets manually
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Using non-MRCOOL parts: Will void warranties and likely result in leaks
🚀 Final Word: Should You Choose the DIY35-1412C?
If your MRCOOL mini split system uses a 1/2" suction line and your total refrigerant line run is close to 35 feet, then yes — the DIY35-1412C is likely your perfect match. It makes installation fast, clean, and worry-free.
But if your unit uses smaller fittings or you need more reach, it’s worth exploring other MRCOOL lineset options like:
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DIY35-1438C (for 3/8" suction lines)
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DIY50-1412C (for longer runs)
Still unsure? Contact The Furnace Outlet for expert advice before placing your order.
💡 Pro Tip from Mark: "Measure twice, order once. The right lineset saves hours of frustration later."
In the next topic we will know more about: Installing the 35ft MRCOOL Lineset: What Mark Learned the Hard Way
