DIY or Hire a Pro? Tony’s Take on Installing His 1-Zone Mini Split

If you're like Tony — a savvy homeowner who loves tackling projects but also knows when to bring in help — this guide will walk you through everything you need to consider before deciding to DIY your ductless install or call in a pro.

✅ Why This Question Matters

More homeowners than ever are installing single-zone mini split systems to control the temperature in garages, bedrooms, studios, and home offices. With brands like MRCOOL offering fully DIY-capable kits, the temptation to save hundreds in labor costs is real.

But DIY doesn’t always mean easy.

Will you void your warranty?
Can you safely handle 220V wiring?
Are your tools sufficient for a leak-proof install?

Tony wrestled with the same questions before installing his 18,000 BTU system in the garage. Let’s look at what’s really involved.

🧰 What’s in the Box: What a DIY Kit Includes

Most DIY-friendly mini split kits (like those from MRCOOL or Pioneer) include:

✅ Indoor wall-mounted air handler
✅ Outdoor condenser unit
✅ Pre-charged refrigerant line set (typically 16, 25, or 35 feet)
✅ Control wire bundle
✅ Remote or wall thermostat
✅ Mounting bracket and drain line

What’s not included:

❌ Wall sleeve or hole cover
❌ High-torque drill for masonry
❌ Conduit or cable clamps
❌ Electrical disconnect box and whip kit

📦 See what comes in the MRCOOL DIY kit: MRCOOL DIY 3rd Gen Unboxing

Tony’s tip: “Unpack and inspect everything the day it arrives. You don’t want to find a kinked line set mid-install.”

📋 Installation Overview: 10 Major Steps

Installing a single-zone system isn’t overly technical — but it does demand precision. Here’s what’s involved:

Find an indoor wall with proper clearance
Drill a 3" hole through the wall for line set and wiring
Mount the indoor air handler using a level bracket
Install the outdoor condenser on a pad or bracket
Feed the line set and wires through the wall to the condenser
Connect drain line and slope it correctly
Wire the condenser to your home’s electrical panel (usually 220V)
Attach line set and torque to spec using provided fittings
Power up the unit and test for cooling/heating
Adjust settings and verify airflow, temperature, and condensate drainag

🧠 Should You DIY? 5 Questions to Ask Yourself

Before picking up a drill, consider these questions:

1. Are you confident using power tools?

Drilling a hole through wood, vinyl, or brick siding takes strength and accuracy.

2. Can you safely work around 220V circuits?

Many single-zone systems require a dedicated 240V breaker. Mistakes can be deadly.

3. Do you understand torque specs and flaring?

Even pre-charged lines need precise tightening to prevent leaks.

4. Can you lift and maneuver a 100+ lb condenser?

Solo installs can be risky without help. Use a dolly or team up.

5. What’s your time worth?

A DIY install could take 6–10 hours. Factor in your learning curve.

Tony’s take: “I’m comfortable with tools, but I still brought in an electrician to handle the breaker panel work.”

👷 When to Call a Pro

Hiring an HVAC technician may be necessary — or even legally required — in situations like:

You need a permit or inspection from your city
Your home’s wiring isn’t ready for 220V
You’re cutting through brick, stucco, or concrete
The indoor unit must be installed on a second story
You’re unsure about refrigerant or torque specs

📍 Find a licensed installer through Energy Star’s locator

💵 Cost Comparison: DIY vs. Pro Install

Installation Type	Estimated Cost
DIY with MRCOOL kit	$0 labor (plus tools)
DIY + licensed electrician	$300–$600
Full pro install	$1,200–$2,000+

Extra Costs to Budget For:

Hole saw for 3" line set opening: $35–$80
Disconnect box + whip kit: $60–$120
Mounting bracket or pad: $80–$150
Wall sleeve, sealant, conduit: $40–$100

Tony’s budget breakdown:

Tools & parts: $200
Electrician for panel wiring: $400
Saved over $1,000 compared to pro install

🗣️ Tony’s Story: Installing a Garage System Solo

Tony’s 2-car garage (575 sq. ft) needed serious cooling for summer workouts. Here’s how it went:

Unit chosen: 18,000 BTU MRCOOL DIY
Tools needed: Hammer drill, torque wrench, conduit bender
Hardest part: Drilling the wall without damaging siding
Pro help: Called in a friend (electrician) for breaker install
Outcome: “Runs great. Took 2 Saturdays and a lot of measuring — but it was worth it.”

⚠️ Common DIY Mistakes & How to Avoid Them

❌ Cutting line set too short (measure twice!)
❌ Forgetting to slope drain line (can cause water backup)
❌ Skipping torque wrench use (leads to refrigerant leaks)
❌ Not sealing wall penetration (invites pests and drafts)
❌ Misreading power requirements (breaker size, wire gauge)

Tony’s tip: “Take your time. Watch 3–5 YouTube installs before touching anything.”

🧾 Permits, Warranties & Legal Fine Print

Check local code for HVAC permits — especially electrical work
Some brands void warranty if not professionally installed (not MRCOOL, but others do)
Insurance may not cover damage from DIY electrical work
Always pull a permit if required — it protects you if issues arise

🔎 Use PermitPlace.com to check by ZIP code

🧠 Conclusion: Tony’s Final Advice

Tony says:

“If you’re mechanically inclined and patient, a single-zone install is doable. But don’t cheap out on tools or safety. And if you’re unsure, call a pro — even just for part of the job.”