When Mike started converting his garage into a guest suite, he faced the same question many homeowners and landlords do: What’s the most cost-effective, space-efficient way to heat and cool a small area without running ductwork? For Mike—and thousands like him—the answer might be a PTAC unit (Packaged Terminal Air Conditioner).
But is it right for your setup? Whether you’re outfitting a rental, studio, or in-law suite, this detailed guide helps you determine if a PTAC is the best fit.
📏 What Is a PTAC Unit? A Quick Primer
A PTAC (Packaged Terminal Air Conditioner) is a self-contained heating and cooling system, typically installed through an exterior wall. They’re widely used in hotels, senior living communities, small offices, and increasingly in residential spaces like guest houses or apartments.
Key characteristics:
-
Through-the-wall design (needs a wall sleeve and venting to outside)
-
Offers both cooling and heating (via electric resistance or heat pump)
-
Runs on 208/230V power
-
Typically ranges from 7,000 to 15,000 BTUs
📚 Learn more about PTAC criteria on ENERGY STAR
📐 How Many BTUs Do You Need? Room Size Sizing Chart
Getting the size right is crucial. Too small, and the unit won’t cool or heat effectively. Too large, and you’ll waste energy and money.
| Room Size (sq. ft.) | Suggested PTAC BTU Rating |
|---|---|
| Up to 300 | 7,000 – 9,000 BTUs |
| 300 – 450 | 9,000 – 12,000 BTUs |
| 450 – 600 | 12,000 – 15,000 BTUs |
| 600 – 750+ | May need two units or a mini split |
🧠 Note: Adjust sizing based on insulation quality, ceiling height, sun exposure, and occupancy.
📖 ENERGY STAR’s Room AC Sizing Guidelines
🏘️ Best Use Cases for PTACs in Residential Spaces
PTAC units shine in these types of installs:
1. Studio Apartments
-
No ductwork required
-
Wall install preserves floor space
-
Quiet operation with zoned control
2. In-Law Suites or Backyard ADUs
-
Independent temperature control
-
Easy to install during renovation
-
Energy-efficient in small, contained areas
3. Garage Conversions
-
No need to tap into existing HVAC system
-
Ventilation is simple with through-wall configuration
4. Rental Units
-
Great for landlords: long-lasting, low maintenance
-
Tenants can control their own comfort
-
Easy to replace without touching central HVAC
🧱 PTAC vs. Other Small-Space HVAC Options
| System Type | Installation | Cooling + Heating | Best For | Cost Range |
|---|---|---|---|---|
| PTAC | Through-wall | ✅ Both | Studios, rentals, ADUs | $800–$1,800 |
| Window Unit | Window only | ❌ Cooling only | Temporary installs | $200–$700 |
| Ductless Mini Split | Wall-mounted | ✅ Both | Zoned, larger spaces | $2,000–$5,000+ |
| Portable AC | Floor space | ❌ Cooling only | Short-term use | $300–$800 |
📎 Energy.gov comparison of AC systems
⚡ Energy Efficiency: What to Look For in a PTAC
All PTACs must meet U.S. Department of Energy standards. However, top-performing models go a step further by qualifying for ENERGY STAR certification, meaning:
-
10% more efficient than federal minimums
-
Lower operational costs
-
Reduced greenhouse gas emissions
✅ Check ENERGY STAR-certified PTACs
📌 Tip from Mike: Look for high EER (Energy Efficiency Ratio) and CEER (Combined Energy Efficiency Ratio) ratings—especially important if you’re running the unit year-round.
🛠️ Installation Considerations for Apartments and Guest Suites
If Mike’s going the DIY route, here’s what he (and you) should know:
1. Wall Sleeve Is a Must
-
Provides structural support and insulation
-
Comes in standard sizes (typically 42" wide)
2. Power Supply
-
Most PTACs require 208/230V power
-
May need a dedicated circuit breaker
3. Drainage
-
Condensate pan and drainage hose for moisture management
-
Some models offer internal or external drainage options
4. Wall Thickness
-
Walls should be 5–8 inches thick
-
Avoid installing in non-exterior walls
💵 Operating Costs & Utility Tips
PTACs can be very affordable to run—if sized and installed correctly. Consider the following:
🧾 Monthly Cost Estimate (Electric Heat PTAC, 12k BTU):
-
Cooling (summer): ~$30–$60/month
-
Heating (winter): ~$40–$90/month
Based on national average of $0.15/kWh
🧠 Tips for Efficiency:
-
Install programmable thermostats (many PTACs support this)
-
Clean filters monthly
-
Block direct sunlight with curtains
🔌 Should You Choose Heat Pump or Electric Resistance?
If you’re in a mild climate, go with a PTAC heat pump—it’s more efficient for heating.
But if Mike lives in a cold climate, electric resistance heat is more reliable (though less efficient).
| Feature | Heat Pump PTAC | Electric Resistance PTAC |
|---|---|---|
| Heating Efficiency | High (3:1 COP) | Lower (1:1 COP) |
| Cold Climate Suitability | ❌ Below 30°F = weak | ✅ Works in all temps |
| Monthly Cost | Lower | Higher |
🎯 NREL Guide to Heat Pump Efficiency
🧰 Maintenance Checklist: Mike’s Monthly PTAC Routine
Keep it running like new by following this simple routine:
-
✅ Clean the filter (every 30 days)
-
✅ Vacuum air intake & vent
-
✅ Check for condensation leaks
-
✅ Inspect the wall sleeve & gasket seal
-
✅ Wipe down the thermostat controls
Once per year:
-
❄️ Deep clean the evaporator coil
-
💨 Blow out the drain line
-
⚙️ Check heating element or heat pump condition
📚 Maintenance Guide – ENERGY STAR
📦 What Mike Should Expect in the Box
Most PTAC packages do NOT include the wall sleeve or grille, so budget for these separately.
| Included | Typically Included? |
|---|---|
| PTAC Unit | ✅ Yes |
| Remote Control | ✅ Usually |
| Wall Sleeve | ❌ Sold separately |
| Grille Cover | ❌ Sold separately |
| Power Cord | ✅ Yes |
| Owner’s Manual | ✅ Yes |
🧾 Final Checklist: Is a PTAC Right for Mike?
-
✅ Space under 600 sq. ft.
-
✅ Exterior wall access
-
✅ Wants heating AND cooling
-
✅ Can install 208/230V circuit
-
✅ Prefers low upfront cost
If you answered “yes” to most of these, a PTAC is a great solution.
🔗 Shop Best-Selling PTAC Units at The Furnace Outlet
🔚 Conclusion: Mike’s Verdict
After comparing all the options, Mike went with a 12,000 BTU GE Zoneline heat pump PTAC for his 450 sq. ft. guest suite. It gave him efficient heating, fast cooling, and a sleek through-the-wall install—without the need for ductwork or mini split complexity.
Whether you're like Mike or managing a small rental property, PTACs offer a reliable and cost-effective HVAC solution that punches above its size.
In the next topic we will know more about: Heat Pump vs. Electric Heat PTACs: Which Option Saves You More in the Long Run?
