🧰 Through-the-Wall Heat Pump Installation Guide: What Jake Learned Doing It Himself
Persona: Jake – A hands-on, measure-twice-cut-once kind of guy who likes saving money with DIY, but knows where to draw the line before a job turns into a disaster.
☕ Introduction — Why I Decided to Install It Myself
I’ve always been the kind of homeowner who looks at a project and thinks, “I can do that”. Sometimes that works out beautifully (like my kitchen backsplash), and sometimes… well, let’s just say there’s a reason my deck rail is now on version three.
When my old window AC and electric space heater were guzzling electricity and barely keeping my home office comfortable, I started shopping for a through-the-wall heat pump. They’re sleek, efficient, and work year-round. The only catch? Installation can cost $500–$1,000+ if you hire a pro.
That was enough for me to start researching a DIY install. I learned a ton—and I’ll share the step-by-step process, rookie mistakes to avoid, and exactly when to call in a professional.
Best Through The Wall Heat Pumps
🛠 Tools & Materials Checklist
Before you start, make sure you’ve got the right gear on hand. Nothing kills momentum faster than having to run to the hardware store halfway through.
Basic Tools:
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Tape measure
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Level
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Stud finder
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Reciprocating saw (or circular saw with masonry blade for brick walls)
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Drill with assorted bits (masonry bits if brick)
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Screwdrivers (Phillips and flathead)
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Utility knife
Materials:
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Wall sleeve (specific to your heat pump model)
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Through-the-wall heat pump unit
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Insulation foam sealant
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Exterior-grade caulk
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Trim kit (optional, for a clean finish)
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Flashing (for weatherproofing exterior)
Safety Gear:
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Safety goggles
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Heavy-duty gloves
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Dust mask or respirator
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Ear protection
Resource: If you’re not sure about a particular tool, check out this installation tool guide from Family Handyman (FamilyHandyman.com).
📏 Planning the Install — Avoiding Rookie Mistakes
The prep stage is where most DIY installs either get set up for success or head straight toward frustration.
1. Choosing the Right Location
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Pick an exterior-facing wall with clear access both inside and outside.
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Avoid walls where furniture or drapes could block airflow.
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Check clearance requirements—most manufacturers specify a minimum outdoor clearance for airflow.
Reference: ENERGY STAR’s clearance guidance (EnergyStar.gov).
2. Checking for Hazards
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Use a stud finder to locate wall studs.
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Watch for electrical wiring—cutting into that is a shocking experience you don’t want.
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Look for plumbing lines—especially if you’re working on a shared wall near a bathroom or kitchen.
3. Confirming the Wall Type
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Wood framing: Easier to cut and frame.
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Brick or concrete: Requires masonry blades and more patience.
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Load-bearing wall: Still possible, but you may need to add extra framing.
🧰 Step-by-Step Installation Process
This is the exact process I followed, with notes on where I slowed down and double-checked my work.
Step 1: Prep the Wall Opening 📐
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Measure your wall sleeve dimensions twice—most are slightly larger than the unit itself.
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Mark your cutout on the wall using a level to ensure it’s perfectly square.
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Use painter’s tape to outline the cut—this helps prevent chipping or splintering.
Step 2: Cut the Opening 🔪
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For drywall: Use a utility knife to score first, then a reciprocating saw for the through-cuts.
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For exterior siding or brick: Drill pilot holes in each corner and use a reciprocating saw with the appropriate blade (or an angle grinder for brick).
Tip from Jake: If you’re cutting masonry, go slow and wear a respirator—dust is no joke.
Reference: Cutting tips from This Old House (ThisOldHouse.com).
Step 3: Install the Wall Sleeve 🧱
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Slide the sleeve into the opening from the inside.
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Make sure it’s pitched slightly downward toward the outside for proper drainage.
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Secure the sleeve to the framing using screws.
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Fill any gaps between the sleeve and wall with spray foam insulation.
Note: The wall sleeve is not optional—it protects the unit and ensures a snug, weatherproof fit.
Step 4: Slide in the Unit 📦
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Most through-the-wall units weigh between 70–120 lbs—grab a helper.
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Align the unit’s tracks with the sleeve and slide it in slowly.
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Ensure it’s seated fully, with no gaps.
Step 5: Connect Power ⚡
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Check your model’s voltage requirement—common options are 115V or 230V.
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Plug into a dedicated outlet.
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If a dedicated circuit is required, or if wiring is needed, this is pro territory.
Reference: Electrical safety per the National Electrical Code (NFPA.org).
Step 6: Seal & Finish 🧼
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Apply exterior-grade caulk around the sleeve outside.
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Install any provided flashing to direct rainwater away.
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Use the trim kit inside for a clean finish.
⚠ Common DIY Installation Mistakes to Avoid
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Forgetting the drainage pitch — water backs up into your wall.
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Cutting too large — you’ll have gaps to fill and possible air leaks.
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Skipping insulation around the sleeve — invites drafts and reduces efficiency.
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Not checking electrical capacity — can blow breakers or damage your unit.
Resource: Troubleshooting installation errors from HVAC.com (HVAC.com).
✅ Testing the Unit — Jake’s “First Run” Checklist
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Turn it on in cooling mode—check airflow and temp drop.
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Switch to heating mode—listen for smooth operation.
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Check condensate drainage outside.
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Inspect for any unusual noises or vibrations.
📞 When to Call a Pro
Even the most confident DIYers need backup sometimes.
Call a licensed installer if:
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You discover structural issues (load-bearing wall complications).
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Electrical upgrades are needed (new circuit, voltage changes).
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You find plumbing or hidden wiring.
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You’re working in masonry and don’t have the right tools.
Reference: Find vetted contractors on Angi (Angi.com).
💬 Jake’s Final Thoughts — Was DIY Worth It?
For me, yes—but only because I took my time, had the right tools, and wasn’t afraid to stop and research when I hit something new.
Total savings: About $700 in labor.
Total time: Roughly 5 hours split over two days.
Would I do it again? Absolutely, but I’d still hire an electrician for the wiring part if I didn’t already have the right outlet in place.
If you’re the type to rush, skip instructions, or hope for the best with power tools—hire a pro. If you’re methodical and patient, this is a totally doable weekend project.
External References in This Guide:
In the Next Topic we will know more about: Best Wall Sleeve Options for Heat Pumps: Compatibility, Fit & Noise Reduction
