🧰 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:

• Tape measure

• Level

• Stud finder

• Reciprocating saw (or circular saw with masonry blade for brick walls)

• Drill with assorted bits (masonry bits if brick)

• Screwdrivers (Phillips and flathead)

• Utility knife

Materials:

• Wall sleeve (specific to your heat pump model)

• Through-the-wall heat pump unit

• Insulation foam sealant

• Exterior-grade caulk

• Trim kit (optional, for a clean finish)

• Flashing (for weatherproofing exterior)

Safety Gear:

• Safety goggles

• Heavy-duty gloves

• Dust mask or respirator

• 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

• Pick an exterior-facing wall with clear access both inside and outside.

• Avoid walls where furniture or drapes could block airflow.

• Check clearance requirements—most manufacturers specify a minimum outdoor clearance for airflow.

Reference: ENERGY STAR’s clearance guidance (EnergyStar.gov).

2. Checking for Hazards

• Use a stud finder to locate wall studs.

• Watch for electrical wiring—cutting into that is a shocking experience you don’t want.

• Look for plumbing lines—especially if you’re working on a shared wall near a bathroom or kitchen.

3. Confirming the Wall Type

• Wood framing: Easier to cut and frame.

• Brick or concrete: Requires masonry blades and more patience.

• 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 📐

1. Measure your wall sleeve dimensions twice—most are slightly larger than the unit itself.

2. Mark your cutout on the wall using a level to ensure it’s perfectly square.

3. Use painter’s tape to outline the cut—this helps prevent chipping or splintering.

---

Step 2: Cut the Opening 🔪

• For drywall: Use a utility knife to score first, then a reciprocating saw for the through-cuts.

• 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 🧱

1. Slide the sleeve into the opening from the inside.

2. Make sure it’s pitched slightly downward toward the outside for proper drainage.

3. Secure the sleeve to the framing using screws.

4. 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 📦

• Most through-the-wall units weigh between 70–120 lbs—grab a helper.

• Align the unit’s tracks with the sleeve and slide it in slowly.

• Ensure it’s seated fully, with no gaps.

---

Step 5: Connect Power ⚡

• Check your model’s voltage requirement—common options are 115V or 230V.

• Plug into a dedicated outlet.

• 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 🧼

1. Apply exterior-grade caulk around the sleeve outside.

2. Install any provided flashing to direct rainwater away.

3. Use the trim kit inside for a clean finish.

---

⚠ Common DIY Installation Mistakes to Avoid

1. Forgetting the drainage pitch — water backs up into your wall.

2. Cutting too large — you’ll have gaps to fill and possible air leaks.

3. Skipping insulation around the sleeve — invites drafts and reduces efficiency.

4. 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

1. Turn it on in cooling mode—check airflow and temp drop.

2. Switch to heating mode—listen for smooth operation.

3. Check condensate drainage outside.

4. 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:

• You discover structural issues (load-bearing wall complications).

• Electrical upgrades are needed (new circuit, voltage changes).

• You find plumbing or hidden wiring.

• 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:

1. Family Handyman – Installing an AC in a Wall

2. Energy Star – Clearance Guidelines

3. This Old House – Cutting Drywall

4. National Electrical Code – NFPA

5. HVAC.com – Through-the-Wall AC Installation
   

In the Next Topic we will know more about: Best Wall Sleeve Options for Heat Pumps: Compatibility, Fit & Noise Reduction