MRCOOL Line Set Installation Guide: Can You Route the Line Set Left, Right, or Straight Out the Back?
One of the most common questions homeowners and installers ask during a MRCOOL® mini split installation is:
“Should or can the line set come out the left side, right side, or straight out the back of the air handler?”
The good news is that MRCOOL® air handlers are designed with installation flexibility in mind. Most models include factory-molded side knockouts that allow refrigerant lines, communication wire, and drain tubing to be routed out the left or right side when needed.
However, just because side routing is possible doesn’t necessarily mean it’s the best option.
For maximum reliability, optimal performance, and the lowest risk of installation problems, MRCOOL DIRECT recommends routing the line set straight out the back of the indoor unit whenever possible.
Let’s look at why.
What Is a Mini Split Line Set?
A line set consists of insulated copper refrigerant lines that connect the indoor air handler to the outdoor condenser.
These lines are responsible for transporting refrigerant between the two components, allowing your MRCOOL system to heat and cool efficiently.
A typical MRCOOL installation may include:
- Refrigerant lines
- Communication wire
- Condensate drain line
- Protective insulation
Because refrigerant flow is critical to system performance, proper line set routing is extremely important.
Can MRCOOL Line Sets Exit the Left or Right Side?
Yes.
Most MRCOOL air handlers are manufactured with pre-scored side knockouts that allow installers to route the line set:
Left Side Exit
Ideal when:
- Outdoor unit is positioned on the left side of the home
- Interior wall conditions limit rear routing
- Existing installations require side access
Right Side Exit
Ideal when:
- Outdoor unit is positioned on the right side
- Existing structures prevent rear exits
- Installation constraints require alternate routing
Rear Exit (Recommended)
Ideal when:
- Exterior wall is directly behind the air handler
- Shortest route to the condenser is available
- Maximum system reliability is desired
Why Straight Out the Back Is Usually the Best Choice
Although side exits are available, routing the line set directly through the wall behind the indoor unit offers several advantages.
Less Stress on Copper Lines
Rear exits require fewer bends and less manipulation of the refrigerant tubing.
This helps prevent:
- Line damage
- Pinched tubing
- Restricted refrigerant flow
- Installation errors
Reduced Risk of Kinks
One of the biggest threats to any mini split installation is a kinked refrigerant line.
Sharp bends can:
- Restrict refrigerant movement
- Reduce cooling capacity
- Increase operating pressures
- Reduce efficiency
- Shorten compressor life
Straight rear routing significantly reduces this risk.
Cleaner Installation
A rear exit typically creates:
- Better appearance
- Less visible piping
- Easier line hide installation
- Simpler wall penetrations
Many professional installers prefer rear exits for aesthetic reasons alone.
Improved Long-Term Reliability
Reducing strain on refrigerant lines helps maintain proper refrigerant flow throughout the life of the system.
That translates into:
- Better efficiency
- Improved performance
- Fewer service issues
- Longer equipment lifespan
Common Problems with Side Line Set Routing
Side exits can be successfully installed, but they require additional care.
Potential problems include:
Kinked Refrigerant Lines
Copper tubing can collapse if bent too tightly.
Pinched Line Sets
Tight installations may squeeze refrigerant lines against framing or cabinet edges.
Cabinet Contact
Improper routing can cause vibration points where tubing rubs against metal surfaces.
Reduced Refrigerant Flow
Any restriction in the line set can negatively impact performance.
Compressor Stress
When refrigerant flow is restricted, the compressor may work harder than intended.
Over time, this can contribute to premature wear.
How to Properly Route a MRCOOL Line Set Out the Side
If a side exit is necessary, follow these best practices.
Step 1: Locate the Factory Knockout
MRCOOL air handlers include molded knockout locations specifically designed for side routing.
These areas are intended to be removed when required.
Step 2: Carefully Cut the Knockout
Using tin snips or appropriate cutting tools:
- Follow the molded outline
- Remove only the intended section
- Avoid damaging surrounding cabinet material
Step 3: Protect the Refrigerant Lines
Install protection where tubing passes through the opening.
Recommended protection includes:
- Rubber grommets
- Protective sleeves
- Additional insulation
- Edge guards
This helps prevent long-term vibration damage.
Step 4: Form Smooth Bends
Avoid tight bends.
Always maintain a gentle radius when bending refrigerant tubing.
The smoother the bend, the lower the risk of restrictions.
Step 5: Inspect Before Finalizing Installation
Before powering up the system:
- Verify no kinks exist
- Confirm insulation is intact
- Ensure tubing isn’t rubbing against metal
- Check communication wire routing
- Confirm drain line slope
MRCOOL DIY® Installations and Line Set Routing
For MRCOOL DIY® systems, proper line set handling is especially important because the pre-charged QuickConnect® line set contains factory-sealed refrigerant connections.
Careful routing helps:
- Protect QuickConnect fittings
- Prevent line damage
- Ensure proper refrigerant flow
- Maintain installation integrity
Whether you’re installing a DIY® 5th Gen, DIY Easy Pro®, DIY Select®, Multi-Zone, Universal®, or Central Ducted system, VersaPro or signature TrueInverter, minimizing unnecessary bends will always improve installation quality.
Frequently Asked Questions
Can a MRCOOL line set come out the side?
Yes. MRCOOL air handlers include factory knockouts that allow line sets to exit either side when necessary.
What is the best direction to route a mini split line set?
Straight out the back is typically the best option because it reduces bends, minimizes stress on the refrigerant lines, and lowers the risk of kinks.
Can a kinked line set damage my mini split?
Yes. Restricted refrigerant flow can reduce performance, increase operating pressures, and potentially contribute to compressor damage over time.
Should I use protection around the side exit opening?
Absolutely. Protective sleeves, grommets, and insulation help prevent rubbing and vibration damage.
Is rear routing always possible?
Not always. Existing construction, structural obstacles, or installation limitations may require left-side or right-side exits.
Why Buy MRCOOL Line Sets from MRCOOL DIRECT?
At MRCOOL DIRECT, we offer genuine MRCOOL line sets, accessories, installation materials, and technical support to help homeowners and contractors complete successful installations.
Benefits include:
- Genuine MRCOOL products
- DIY® QuickConnect® line sets
- Multi-zone accessories
- Fast shipping
- Expert support
- Competitive pricing
Whether you’re installing a single-zone DIY® mini split or a large multi-zone system, proper line set routing can make a significant difference in performance, reliability, and long-term system life.
When possible, keep it simple: straight out the back remains the best route for most MRCOOL air handler installations.
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