When shopping for a new air handler, it’s easy to focus on tonnage, SEER2 ratings, or whether the system is R-32 compatible. But there’s another feature inside the Goodman 2 Ton R-32 Compatible Wall-Mounted Air Handler (Model AWST24SU1308) that plays a huge role in performance: the built-in thermal expansion valve (TXV).
Mark, a hands-on homeowner who’s learned HVAC the DIY way, says:
“When I bought my first air handler, I didn’t even know what a TXV was. Now? I wouldn’t buy a system without one. It’s like the difference between driving a car with cruise control versus constantly pumping the gas pedal yourself.”
So, what exactly does a TXV do, and why should you care that Goodman includes one in this model? Let’s break it down.
🔧 What Is a TXV (Thermal Expansion Valve)?
At its core, a TXV regulates how much refrigerant enters the evaporator coil.
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It meters refrigerant flow based on the heat load inside your home.
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It responds to changes in temperature and pressure.
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It ensures your coil gets exactly the right amount of refrigerant—no more, no less.
Without a TXV, many systems rely on a fixed orifice (piston), which allows refrigerant flow at a set rate no matter the conditions. That can work fine in mild weather, but under heavy loads (hot, humid summers), it often leads to inefficiency.
👉 The Air Conditioning Contractors of America (ACCA) explains that expansion devices are critical for balancing refrigerant and maximizing system efficiency (ACCA HVAC Fundamentals).
⚙️ How the TXV Works
The TXV has three main components:
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Sensing Bulb: Monitors refrigerant temperature leaving the evaporator.
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Diaphragm/Valve: Opens or closes to adjust refrigerant flow.
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Spring/Adjuster: Balances pressure and fine-tunes operation.
When indoor load increases (like a hot day with people cooking and appliances running), the TXV opens wider, allowing more refrigerant into the coil. When the load decreases, it throttles back.
Think of it as your system’s “thermostat for refrigerant.”
⚡ Why the Built-In TXV Matters
So why is it such a big deal that Goodman installs a TXV at the factory instead of leaving it as an add-on?
1. Higher Efficiency (SEER2 Ratings)
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TXVs optimize refrigerant flow, which boosts efficiency under variable loads.
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According to the DOE, correct metering devices can significantly improve energy performance (DOE – Central AC).
Mark noticed this firsthand:
“When I switched from a piston system to one with a TXV, my summer electric bill dropped by about 15%. Same house, same thermostat setting, just a smarter air handler.”
2. Better Humidity Control
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Oversupplied refrigerant = poor dehumidification.
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TXVs prevent this by matching flow to coil demand.
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You feel cooler and drier even at slightly higher thermostat settings.
👉 The EPA Energy Star program emphasizes proper moisture control as a comfort and health factor (Energy Star Guide).
3. Longer Compressor Life
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A fixed orifice often starves or floods the compressor.
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TXVs reduce mechanical stress, extending lifespan.
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This saves homeowners thousands in premature failures.
Mark compares it to cars:
“Running an AC without a TXV is like driving a stick shift uphill and never shifting gears. The engine wears out faster.”
4. R-32 Compatibility
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R-32 refrigerant operates at slightly different pressures than R-410A.
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A TXV can adapt to these conditions better than a fixed metering device.
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Goodman’s AWST24SU1308 is designed to be future-proof, and the TXV is part of that.
👉 The AHRI Directory confirms that TXV-equipped units handle refrigerant transitions more smoothly (AHRI Directory).
5. Factory Installation = Fewer Errors
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TXVs can be field-installed, but mistakes happen.
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Goodman’s factory installation means it’s properly set and tested.
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Saves time for installers and avoids warranty headaches.
🏠 Mark’s Real-World Experience
Mark once owned a townhouse with a 2.5-ton system using a piston metering device.
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Problem: Inconsistent cooling—cold mornings, sticky afternoons.
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Result: Compressor burned out in 6 years.
Later, when he upgraded to a Goodman unit with a TXV:
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Result: Even temperatures, better humidity control, and lower bills.
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Lesson: The TXV was the difference-maker.
“I didn’t understand it at the time, but that little valve was saving my compressor’s life. Now, whenever friends ask me about HVAC, the first thing I tell them is: make sure it has a TXV.”
📉 What Happens Without a TXV?
If you buy an air handler without a TXV:
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Efficiency Losses: The system may meet SEER2 lab ratings but underperform in real life.
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Comfort Issues: Uneven cooling and poor humidity removal.
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Wear and Tear: Shorter system lifespan due to compressor stress.
👉 The Building Performance Institute (BPI) warns that poor refrigerant control is a leading cause of HVAC failures (BPI Resources).
🛠️ TXV vs. Fixed Orifice: Side-by-Side
| Feature | Fixed Orifice (Piston) | TXV |
|---|---|---|
| Efficiency | Lower, fixed flow | Higher, adaptive flow |
| Humidity Control | Poor | Excellent |
| Compressor Stress | Higher risk | Reduced risk |
| Compatibility | Limited with new refrigerants | Flexible, R-32 ready |
| Cost | Cheaper upfront | Higher upfront, better long-term savings |
🔍 Who Benefits Most from a TXV?
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Homes in Humid Climates: Better moisture removal.
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Variable Load Homes: Large windows, kitchens, or occupancy shifts.
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DIYers Like Mark: Fewer field adjustments, more consistent performance.
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Future-Proof Buyers: Ready for R-32 refrigerant phase-in.
📊 Infographic Idea
“TXV vs. Piston: The Cruise Control Difference”
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Left side: car constantly hitting brakes/gas = piston.
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Right side: car on cruise control = TXV.
📋 Quick Takeaway
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The Goodman AWST24SU1308 comes with a built-in TXV.
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This means higher efficiency, better comfort, longer system life, and R-32 readiness.
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Mark’s advice: “Don’t cheap out. A TXV may be small, but it makes a big difference in how happy you’ll be with your AC.”
In the next topic we will know more about: R-32 Compatibility Explained: Why This Air Handler is Future-Ready
