⚠️ 1. Why a Pre-Install Checklist Matters
Proper planning makes a MRCOOL DIY install:
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Safer
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Cleaner
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Faster
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More energy efficient
Quick Connect lines remove the need for refrigerant charging, but you still need to think ahead about wall routing, breaker loads, and line set layout.
🏠 2. Planning the Installation Layout
Before opening the box:
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Identify the exact location for all five indoor units
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Sketch the path from each air handler to the outdoor condenser
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Choose which side of each indoor unit the line set will exit (left/right)
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Ensure gravity-assisted drain on all lines
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Avoid routing through studs, joists, or electrical bundles
Tip: Use painter's tape and a laser level to mock out each line run.
Resource: MRCOOL DIY Installation Manual
🛋️ 3. Choosing Line Set Lengths
MRCOOL’s pre-charged line sets come in:
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16 ft
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25 ft
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35 ft
You can also use line set coupler kits to combine segments.
Tips for Line Set Sizing:
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Keep total length under 75 ft per zone
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Avoid excessive slack or tight loops
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Match actual distance + 3–5 ft buffer
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Plan to slope lines slightly downward for condensate drainage
Tool: MRCOOL Line Set Sizing Guide
🛏️ 4. Wall Penetration Guidelines
Each indoor unit needs one 3.5" to 4" hole through the wall.
Do:
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Use a hole saw with dust shroud
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Drill slightly downward from inside out (for drainage)
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Drill near a stud (but not through one)
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Seal gaps with foam or caulk to prevent drafts or pests
Don’t:
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Drill directly above electrical outlets
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Punch through brick without a masonry bit
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Leave line sets exposed to weather
Tip: Install a plastic wall sleeve before feeding through the bundle.
Resource: Senville DIY Mini Split Wall Prep Guide
🔌 5. Wiring and Electrical Checklist
Required Electrical Specs:
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Outdoor unit: 208/230V, typically 30–40A double-pole breaker
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Indoor units: Powered via control cable from condenser
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Disconnect box: Must be installed near outdoor unit
Materials:
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UF-rated electrical cable
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Waterproof conduit (liquid-tight or PVC)
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Line voltage surge protector (recommended)
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Grounding rod (if not already grounded)
Tool: Premium Home Source Install Guide
⚡ 6. Safety Gear and Required Tools
Tools:
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Drill with hole saw (3.5" or 4")
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Level
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Stud finder
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Utility knife
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Wire stripper & crimper
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Caulk gun
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Ladder (for indoor/outdoor work)
Safety Gear:
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N95 mask for drywall dust
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Safety glasses
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Electrical tester
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Gloves (for sharp metal edges)
🔢 7. What to Double-Check Before Drilling
Tony should verify:
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Stud placement and wall integrity
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No hidden electrical or plumbing lines (use a multi-scanner)
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Indoor unit has proper spacing (above windows, shelves, etc.)
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Exterior wall is not obstructed (decking, fencing, gas meter)
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Line sets reach condenser location without sharp bends
Better to measure twice than patch drywall.
🌄 8. Conclusion
Installing a MRCOOL 5-Zone system is completely doable for Tony — but planning and prep are everything.
With the right:
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Measurements
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Line set lengths
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Wall access strategy
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Electrical safety approach
...Tony will save thousands and get professional-grade results.
Use this checklist as your command center before cutting, drilling, or mounting anything.
In the next topic we will read about: How Much Can You Really Save with a DIY MRCOOL 5-Zone Setup?
