The Forgotten Foam Kit — Tony’s Air-Leak Audit That Adds 15% More Heating Efficiency for Free

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By Tony Marino — “If air can sneak through it, you’re paying for heat you never get.”

There’s a dirty little secret in PTAC and heating installs that nobody talks about — not contractors, not equipment manufacturers, not hotel maintenance staff, not even most HVAC pros.

It’s the one thing that kills efficiency every single winter, no matter how good the heat kit is, how expensive the PTAC is, or how big the electric bill gets.

And it’s this:

Most PTAC installations leak more air around the sleeve than they deliver through the vents.

I’ve seen units that waste 10–30% of their heating power just pushing warm air through cracks.

And the worst part?

The fix costs $12 to $20, takes 15 minutes, and requires zero specialized skills.

It’s the foam kit — the one most installers leave in the truck because they’re trying to go home early.

This is the guide nobody teaches: the full Tony-style air-leak audit that boosts efficiency by up to 15% — for free — and stops drafts, noise, bugs, moisture, and heat loss at the same time.

Amana Distinctions Model 12,000 BTU PTAC Unit with 3.5 kW Electric Heat

Let’s get into it.

🧊 1. Why Air Leaks Matter More in Heating Mode Than Cooling Mode

People think of drafts as “comfort issues.”
No — they’re energy hemorrhages.

A 12k PTAC with a 3.5 kW heat kit puts out 11,900 BTUs of heat.

If the sleeve is leaking?

You lose:

5% to cracks around the rough opening
4% to unsealed top corners
6% to pressure reversal from negative outdoor temps
3% to sleeve convection currents
1–3% to wind intrusion

You have 15–20% BTU loss, which shows up as:

Higher energy bills
Slow room warm-up
Heat kit cycling more often
The blower sounding louder
Cold spots and drafts at ankle height

And customers say:

“Tony, the heater seems weak.”

No — your heater’s fine.
Your building envelope is the problem.

🧱 2. The Physics: Heating Air Expands — and That’s Why Leaks Grow in Winter

When the PTAC kicks on in heating mode:

The indoor side heats the sleeve
The sleeve expands upward
Stress cracks form around the drywall
Warm air seeks the nearest escape route
Cold air rushes in behind it
Negative pressure pulls more cold air through gaps

This creates a constant circulation loop:

Warm air → escapes
Cold air → enters
Heat kit → runs harder
Electric bill → climbs
Sleeve → expands more
Air leak → widens

THAT is why winter leaks are 3–5× worse than summer leaks.

And that’s why you MUST audit and seal correctly.

🧰 3. The Forgotten Foam Kit: What It Actually Does

People think a foam kit is “insulation.”

No — it’s airflow geometry control.

A PTAC sleeve isn’t insulated — it’s a pressure chamber.

Foam:

Defines the chamber
Directs airflow
Prevents turbulence
Locks the sleeve in neutral position
Stops cold-air infiltration
Stops warm-air exfiltration
Maintains blower pressure
Preserves the CFM you paid for
Protects the drainage slope
Prevents water intrusion

Done right, the foam kit stabilizes the entire installation so the PTAC can operate like it was engineered to.

Done wrong?

It’s a draft tunnel connected directly to your customer's electric bill.

🔍 4. Tony’s Air-Leak Audit — The Only One That Catches Every Problem

This is my field-tested inspection, the one I use at hotels, apartments, senior living facilities, and home installs.

Takes about 10–12 minutes.
Finds every leak every time.

✔ Step 1 — The Dollar Bill Test

Slide a bill around:

Top corners
Bottom corners
Left and right edges
Grille flange
Sleeve interior

If the bill gets pulled, flutters, or slides behind the trim — you have an air leak.

✔ Step 2 — The Hand Sweep Test

Run your hand around:

Indoor flange
Side trim
Under the unit
Behind curtains
Floor level

If you feel even a hint of cold, that’s a leak.

✔ Step 3 — The Tissue Test

Hold a tissue with one corner near the sleeve edges.

If it moves:

Outward → warm air loss
Inward → draft infiltration

Both cost you money and BTUs.

✔ Step 4 — The Thermal Pattern Test (Optional but powerful)

Use a $50 thermal camera.

Look for:

Cold streaks
Blue halos
Draft trails
Cold pooling at floor

If you see movement patterns, your sleeve is leaking.

✔ Step 5 — The Indoor Condensation Check

This is subtle but critical.

If moisture forms on:

The PTAC trim
The lower drywall
The floor edge
The sill plate

You have cold air infiltration.

✔ Step 6 — The Exterior Wind Direction Check

Walk outside.

Look at:

Wind side
Leeward side
Building height
Stack pressure

Wind will push cold air into the sleeve from outdoors.
Negative pressure will pull warm air out.

This tells you which leaks matter most.

🧱 5. Where 90% of PTAC Air Leaks Actually Occur (Tony’s Map)

These are the exact leak zones I fix every week.

1. The Top Left & Right Corners (Biggest offender)

These gaps form naturally when framing shrinks.

2. The Bottom Sill Edge

Poor slope or foam under the sill creates a draft path.

3. The Sleeve Interior Perimeter

Where sleeve meets wall = open cavity.

4. The Grille-to-Sleeve Joint

Mis-seated grilles cause wind whistling.

5. The Return-Air Bounce Channel

This one is invisible until tested with thermal imaging.

6. The Sidewall Penetrations

Electrical, thermostat, low-voltage chase — all draft paths.

These combined leaks reduce heating efficiency more than a dirty filter.

And nobody seals them… except Tony.

🛠️ 6. How Tony Seals a PTAC Sleeve (The Right Way — Not the Fast Way)

Here’s the part most installers screw up.

They:

Spray too much foam
Use the wrong foam
Foam the wrong areas
Block the drain path
Cause back-pressure
Insulate the airflow path
Seal moisture in

Tony does none of that.

Here’s the exact process.

🧰 Step 1 — Pull the Chassis

Always remove the PTAC body BEFORE sealing anything.

Foam + chassis = bad news.

🧽 Step 2 — Vacuum the Draft Cavities

Dust blocks adhesion.
Clean sleeves seal better.

🧱 Step 3 — Identify the Four Draft Zones

Zone 1: Above the sleeve
Zone 2: Left side
Zone 3: Right side
Zone 4: Below the sleeve

Only these zones get foam.

NOT:

Behind the drain pan
Under the chassis rails
Into the ventilation channels
Into the sleeve interior
Across the top pressure relief

Use foam ONCE you know where it belongs.

✔ Step 4 — Use LOW-EXPANSION Closed-Cell Foam

This is critical.

Low-expansion = won’t warp the sleeve
Closed-cell = won’t absorb moisture

Open-cell or high-expansion foam will:

Change sleeve shape
Alter the slope
Block drainage
Cause condensate spills
Warp grille alignment
Increase sound level
Cause airflow restriction

Low-expansion foam avoids ALL these issues.

🕳 Step 5 — Fill the Cavity, Not the Sleeve

Foam goes into the wall gaps, NOT the sleeve.

Foam touching metal inside the sleeve is a code violation and causes:

Back-pressure
Mold
Noise
Airflow disruption

Keep all foam outside the PTAC’s airflow geometry.

🧼 Step 6 — Shape the Foam After It Cures

Foam expands unevenly.

After 20–30 minutes:

Trim flush
Check for voids
Add backer rod + caulk where needed
Rebuild clean lines

This is why Tony’s installs look professional — no bulging blobs.

🔥 7. How the Air-Leak Fix Adds 15% Heating Efficiency

Here’s the math most installers never bother to learn.

A PTAC without leaks:

Keeps blower static pressure stable
Maintains heat-strip contact temp
Avoids temperature stratification
Reduces run-time up to 12–20%
Increases perceived warmth at floor level
Eliminates cold corners
Stops heat loss into the wall cavity

Here’s what you get with proper sealing:

✔ Higher discharge air temperature

Often +2°F to +5°F boost.

✔ Better thermostat sensing

Less cycling = less wasted heat.

✔ No cold-air infiltration

Every CFM of cold air entering = BTUs wasted.

✔ Consistent static pressure

PTACs LOVE consistent pressure — that’s how they’re engineered.

✔ Lower electric bills

Heat strips are expensive to run.
Running them less saves money.

Most buildings I’ve worked in gain 8–15% heating efficiency instantly — no tools, no advanced math, no equipment upgrades.

Just fixing leaks.

🎯 8. Why This Matters Most for 12k PTAC Units with 3.5 kW Heat Kits

A 3.5 kW heat kit is strong…
But it’s also sensitive to airflow and pressure.

Air leaks:

Make the heat kit run hotter
Make the blower work harder
Cause limit trips
Reduce BTUs delivered
Create cold-floor drafts
Increase perceived noise
Lower discharge temp

12k units move enough CFM that even a 10 sq. inch leak equals a major draft path.

Your foam kit fixes this.

📚 9. External Verified Resources Supporting This Article

Here are reliable resources that align with best practices mentioned in this guide:

Amana PTAC Installation Manual
Energy.gov – Air Sealing Guidelines
https://www.energy.gov/energysaver/air-sealing-your-home
OSHA – Construction Saw Safety (for proper wall cuts)
https://www.osha.gov
International Building Code (Wall Framing Requirements)
https://codes.iccsafe.org/
UL Guidelines for Electric Heat Components
https://ul.com/
ASHRAE Handbook – HVAC Fundamentals (Airflow & Pressure)
https://www.ashrae.org/technical-resources/ashrae-handbook
EPA – Indoor Air & Moisture Control
https://www.epa.gov/mold
Building Science Corporation – Airflow & Thermal Bypass Analysis
https://buildingscience.com