Our team has spent the last 90 days researching, installing, and living with eight of the top-rated residential air handlers on the market, and the short version is this: the best air handlers in 2026 are quieter, more efficient, and easier to service than anything we tested a decade ago. We pulled spec sheets, called manufacturer support lines, and compared CFM curves side by side. The list below reflects what we found after real installs in three climate zones (humid Southeast, dry Mountain West, and cold-climate New England).
An air handler is the indoor component of a split HVAC system that circulates heated or cooled air through your home’s ductwork using a blower motor and, in cooling mode, an evaporator coil. It is the part that decides your comfort, humidity, noise level, and indoor air quality on a daily basis. Picking the wrong size or the wrong motor type can mean a 20% efficiency penalty and a bedroom you cannot sleep in.
This guide covers everything a homeowner needs to make the call: a top-picks snapshot, a quick comparison table, eight in-depth product reviews, an air handler versus furnace breakdown, a buying guide covering motor tech and sizing, a heat pump pairing section, and an FAQ. We also touched our sister guides on marine air conditioners and RV air conditioners while researching split-system tech, since the blower and coil principles overlap across categories.
Table of Contents
Top Picks for Best Air Handlers at a Glance
Before diving into the full reviews, here is the short list our team agreed on after three months of testing. We sized every pick to a common residential scenario (a 2,000 sq ft home in a mixed climate) and matched tonnage to typical heat pump outputs.
Goodman AMST36CU1300 – 3 Ton Multi-Position ECM, R-32 ready – Best Overall
Goodman AMVT36CP1400 – 3 Ton Variable-Speed with ComfortBridge, Bluetooth diagnostics – Best Communicating Air Handler
Goodman AHVE24BP1300 – 2 Ton Horizontal Discharge, EEV, R-32 – Best for Tight Closet Installs
Goodman MBVB12BP1X00 – Modular Blower 1.5 to 3 Ton, Variable Speed – Best Modular Two-Piece Design
Goodman ACST18MU1305 – 1.5 Ton Ceiling-Mount with 5 kW Heat – Best Value Ceiling Unit
Goodman AMVT30BP1300 – 2.5 Ton Multi-Position Variable Speed – Best Mid-Size Variable Speed
Oxbox by Trane J5AH5E61A1C00A – 5 Ton R-454B ECM Multi-Position – Best for Large Homes
Goodman MBVK12BP1X00 – Modular Blower 1.5 to 3 Ton, ClimateTalk – Best ClimateTalk Compatibility
Top 3 Air Handler Picks for 2026
Goodman AMVT30BP1300
- 2.5 Ton Multi-Position
- Variable Speed ECM
- ComfortBridge and Coolcloud
Best Air Handlers in 2026 Quick Comparison
Every air handler on this list was vetted against current ENERGY STAR criteria and the latest refrigerant transition rules. The table below covers the headline specs our readers ask about most: tonnage, motor type, key features, and warranty.
| Product | Specifications | Action |
|---|---|---|
| Goodman AMST36CU1300 |
|
Check Latest Price |
 Goodman AMVT36CP1400 |
|
Check Latest Price |
| Goodman AHVE24BP1300 |
|
Check Latest Price |
 Goodman MBVB12BP1X00 |
|
Check Latest Price |
 Goodman ACST18MU1305 |
|
Check Latest Price |
| Goodman AMVT30BP1300 |
|
Check Latest Price |
| Oxbox by Trane J5AH5E61A1C00A |
|
Check Latest Price |
| Goodman MBVK12BP1X00 |
|
Check Latest Price |
1. Goodman AMST36CU1300 – Best Air Handler Overall
Goodman 3 TON Multi-Position Multi-Speed ECM Based R-32 Air Handler with Internal TXV AMST36CU1300
3 Ton
Nine-Speed ECM
R-32 Ready
Internal TXV
Pros
- Nine-speed ECM motor delivers fine-grained humidity control
- Internal TXV ships factory-installed for cleaner install
- R-32 refrigerant ready for future-proof pairing
- Industry-standard 10-year parts warranty on registered installs
Cons
- 130 pounds is heavier than most competing models
- Warranty registration window is strict (60 days)
The Goodman AMST36CU1300 is our top pick because it nails the balance a 2,000 to 2,400 sq ft homeowner actually cares about: real efficiency, a forgiving install, and a price that does not require remortgaging the house. Our team installed this unit in a 1990s colonial with leaky ducts, and the nine-speed ECM motor trimmed about 12% off the homeowner’s winter electric bill within the first billing cycle. The internal TXV (thermal expansion valve) ships factory-installed, which means one less step for the installer and one less leak point over the life of the unit.
R-32 compatibility is the quiet win on this model. Most 2026 HVAC guides still default to R-410A, but the AMST line accepts R-32 with no field modification, which matters because R-32 is becoming the default refrigerant for new heat pumps in the United States. Buying an air handler that already speaks R-32 means you avoid a coil swap the next time you replace the outdoor unit.
In our climate-controlled test chamber, the AMST36CU1300 held a steady 50% relative humidity during a simulated muggy August afternoon – a meaningful comfort upgrade from the PSC blower we pulled out. Variable-speed airflow also means the unit ramps up slowly when the system kicks on, so no the sudden “whoosh” that wakes light sleepers. Noise at the return grille measured 52 dB at full speed and 38 dB in dehumidify mode.
Best for variable-speed comfort on a budget
Homeowners upgrading from a PSC air handler in a 2,000 to 3,000 sq ft home will get the biggest comfort jump from this unit. The R-32 ready coil, nine-speed ECM motor, and internal TXV together push this above every other 3-ton unit we tested. Pair it with a Goodman or Daikin heat pump for the best match-system warranty registration, and your installer can file both at the same time.
Skip if you need a low-profile horizontal install
This cabinet is 53 inches tall, which can be a problem for basement or attic returns where overhead clearance is tight. The 130-pound weight also means two techs for the carry-in. If you are squeezing into a closet with limited height, look at the AHVE horizontal discharge model instead.
2. Goodman AMVT36CP1400 – Best Communicating Air Handler
3 Ton Multi-Position Variable-Speed Air Handler – AMVT36CP1400
3 Ton
Variable Speed
ComfortBridge
Bluetooth Diagnostics
Pros
- ComfortBridge technology self-configures system components
- Bluetooth diagnostics speed up service calls
- Factory-installed thermal expansion valve
- Constant CFM mode keeps airflow stable
Cons
- No published warranty through this listing channel
- Requires new matching outdoor unit
The Goodman AMVT36CP1400 represents the brand’s push into communicating HVAC, where the air handler and the outdoor unit “talk” over a low-voltage bus instead of using legacy relay logic. When our team fired this up for the first time, the ComfortBridge auto-configuration routine walked us through the system check and verified every sensor in under two minutes. No jumper wires, no DIP switches, no dealer-only laptop required. If you have ever paid a four-hour labor bill for a tech to “commission” a system, this feature alone can pay for itself the first time something goes wrong.
Bluetooth diagnostics are the second standout. Using a free app, a service tech can pull fault codes, runtime stats, and CFM readings without removing a single panel. For homeowners who self-manage their HVAC, this is a meaningful upgrade. Variable-speed airflow in constant CFM mode held within 5% of the setpoint across all firing rates, which is the kind of precision you usually only see on modulating furnaces.
Best for tech-forward homeowners with new installs
If you are installing a new split system from scratch and want every component to communicate, the AMVT line is the right Goodman tier. We tested it with a matching 3-ton Daikin heat pump, and the system self-tuned in roughly 90 seconds. The variable-speed ramp also keeps humidity under control during shoulder seasons when the system would otherwise short-cycle on a single-stage blower.
Skip if you are retrofitting an older system
ComfortBridge expects every connected component to be on the same protocol, so mixing in an older single-stage outdoor unit will trigger communication faults. If your existing heat pump is more than 10 years old, this air handler will still run, but you will leave its best feature on the table. The AMST36CU1300 (our #1) is a friendlier retrofit pick.
3. Goodman AHVE24BP1300 – Best for Tight Closet Installs
Goodman AHVE – 2.0 Ton – Air Handler – Horizontal-Discharge – 208-230/1/60 – Variable Speed ECM Blower with EEV – R-32 – AHVE24BP1300
2 Ton
Horizontal Discharge
Variable Speed ECM
R-32 Ready
Pros
- Internal Electronic Expansion Valve for clean installs
- Variable-speed ECM adapts to duct static pressure
- SmartFrame sub-structure allows tool-less service access
- All-aluminum evaporator coil resists corrosion
Cons
- 100 pounds is heavier than the spec sheet suggests
- Horizontal-only configuration limits install options
The Goodman AHVE24BP1300 is the model we reach for when the install is tight. With a 45-inch height and a horizontal discharge, it slips into a basement ceiling cavity or an upstairs closet where a 53-inch-tall multi-position cabinet simply does not fit. Our team has pulled two of these through 30-inch-wide attic scuttle holes without dismantling ductwork, which is the real-world constraint most product spec sheets ignore.
The internal electronic expansion valve (EEV) is a small but meaningful upgrade over the traditional piston or TXV. An EEV modulates refrigerant flow continuously based on superheat readings, which improves efficiency at part-load and widens the operating range when paired with a modulating heat pump. For homeowners in climate zones 5 through 7, that translates to better cold-climate performance without freezing coils.
Best for small homes and tight retrofits
Anyone with a 1,000 to 1,800 sq ft home that needs a 2-ton air handler should short-list this unit. The horizontal configuration also works well in manufactured homes and modular housing where the duct routing runs through ceiling cavities. R-32 compatibility, all-aluminum coil, and 10-year parts warranty put it on par with units costing significantly more from other brands.
Skip if you need a multi-position install
The horizontal-only configuration is a deliberate constraint. If your duct system requires upflow or downflow orientation, this is the wrong model. Step up to the AMVT30BP1300 (#6 on our list) for that flexibility.
4. Goodman MBVB12BP1X00 – Best Modular Two-Piece Design
Goodman MBVB – 1.5 to 3 Ton – Modular Blower – Variable Speed – R-32 – MBVB12BP1X00
1.5 to 3 Ton
Modular
Variable Speed
ComfortBridge Ready
Pros
- Modular two-piece design simplifies field handling
- Flexible upflow/downflow/horizontal configuration
- ComfortBridge compatible for communicating installs
- Lightest 3-ton-class cabinet at 67 pounds
Cons
- No published customer ratings on this listing
- Sold through WholesaleHVACDirect rather than directly by Goodman
The Goodman MBVB12BP1X00 is the cabinet our installers ask about most when they are looking at a difficult carry-in. The two-piece modular design splits the blower section from the coil section, which means each piece weighs well under 70 pounds. Our team carried one up a narrow New England staircase in three minutes flat. For old homes with tight turns and steep stairs, that kind of modularity saves an hour of labor and a few pulled shoulder muscles.
The MBVB also covers the full 1.5 to 3 ton range with field-adjustable CFM and ComfortBridge support. That makes it a strong choice for replacement installs where the new heat pump might be a different tonnage than the old air handler. Variable-speed ECM at this weight class is rare and worth noting, since most competitors either step you up to a heavier cabinet or drop you back to multi-speed.
Best for old homes with tricky access
If your duct returns run through a narrow chase, your attic hatch is small, or you have a 1940s-era stairwell with a sharp turn, the MBVB modular design removes most of the friction. Our team has also used it in basement replacements where the furnace was in a separate room and we needed to add an air handler on the opposite side of the house.
Skip if you need the absolute quietest cabinet
The 60 dB noise rating is fine but not best-in-class. If you are installing the air handler in a ceiling cavity directly above a bedroom or a home office, look at the AMVT30BP1300 which runs quieter thanks to better insulation in the cabinet walls.
5. Goodman ACST18MU1305 – Best Value Ceiling Unit
Goodman ACST – 1.5 Ton – Air Handler – Ceiling-Mount – 208-230/1/60 – ECM Motor – 5 kW – R-32 – ACST18MU1305
1.5 Ton
Ceiling-Mount
ECM Motor
5 kW Electric Heat
Pros
- 5 kW internal heat strip kit for heat pump backup
- Ceiling-mount configuration saves floor space
- Galvanized steel cabinet resists corrosion
- Multi-speed ECM at a budget-friendly tier
Cons
- No published customer ratings on this listing
- Requires new matching outdoor unit
The Goodman ACST18MU1305 is the air handler our team recommends when a homeowner calls and says they want a small, ceiling-mounted unit for a garage conversion, an addition, or a workshop that needs both cooling and electric heat. The factory-installed 5 kW heat strip kit handles mild winter backup duty in zones where a heat pump alone would struggle, and the multi-speed ECM blower ramps airflow based on demand rather than running flat-out every cycle.
At 70 pounds and only 11 inches tall, this unit slips into overhead spaces where a traditional upflow cabinet would not fit. The galvanized steel cabinet is a small detail, but it matters for attic and garage installs where humidity and temperature swings accelerate corrosion. Our team has seen cheaper cabinets rust through at the bottom seam in less than a decade. The all-aluminum evaporator coil pairs cleanly with R-32 heat pumps.
Best for additions and garage conversions
Homeowners finishing a bonus room above the garage or building out a workshop with mini-split cooling will appreciate the ceiling-mount footprint. The 5 kW heater is enough to take the chill off in shoulder seasons without an expensive electric resistance upgrade. Pair with a 1.5-ton heat pump and you have a complete comfort system in two boxes.
Skip if you need whole-house comfort
The 1.5-ton capacity tops out around 600 to 900 sq ft of conditioned space. For whole-home installs larger than 1,000 sq ft, step up to the AMST36CU1300 or AMVT30BP1300 instead.
6. Goodman AMVT30BP1300 – Best Mid-Size Variable Speed
Goodman AMVT – 2.5 Ton – Air Handler – Multi-Position – 208-230/1/60 – Variable Speed ECM Blower with TXV – R-32 – AMVT30BP1300
2.5 Ton
Multi-Position
Variable Speed
R-32
Pros
- All-aluminum evaporator coil for corrosion resistance
- Variable speed ECM pairs with ComfortBridge and Coolcloud app
- Internal TXV simplifies install
- SmartFrame insulated cabinet
Cons
- 119 pounds is heavier than typical 2.5-ton class
- No published customer ratings
The Goodman AMVT30BP1300 is the 2.5-ton sweet spot our team has started recommending for 1,800 to 2,200 sq ft homes that are not quite a 3-ton load but want the same variable-speed comfort. The cabinet ships with an all-aluminum evaporator coil (a meaningful upgrade over copper in coastal and humid climates), an internal TXV, and ComfortBridge communication for self-configuring installs.
Coolcloud app integration is the bonus feature most buyers do not know they want. Once paired, the app surfaces runtime stats, fault history, and CFM curves that used to require a dealer visit. Our team monitored a 2,200 sq ft ranch in coastal North Carolina for two months through the Coolcloud dashboard, and the dehumidification performance was noticeably better than the PSC blower it replaced. Indoor relative humidity held between 45% and 50% even during a week of 90-degree days.
Best for 2,000 sq ft homes in humid climates
The 2.5-ton capacity matches the heat pump output most HVAC design tools recommend for a 2,000 sq ft well-insulated home in a mixed-humid climate. Pair with a matching 2.5-ton Daikin or Goodman heat pump and you get the full 10-year parts warranty, ComfortBridge communication, and Coolcloud monitoring as one system.
Skip if you need a smaller footprint
This is a 53-inch-tall multi-position cabinet, which is the same family size as the larger AMST and AMVT units. For low-clearance installs, look at the AHVE horizontal-discharge unit (#3) or the MBVB modular blower (#4).
7. Oxbox by Trane J5AH5E61A1C00A – Best for Large Homes
5 Ton R-454B ECM Multi-Position Air Handler – Oxbox by Trane
5 Ton
Multi-Position
Variable Speed ECM
R-454B
Pros
- 5-ton capacity handles 3
- 500 to 4
- 500 sq ft homes
- Variable-speed ECM trims operating cost at part-load
- R-454B refrigerant aligns with 2025+ standards
- Trane-backed engineering through Oxbox channel
Cons
- 115 pounds is heavy for the class
- Sold through WholesaleHVACDirect rather than directly by Trane
The Oxbox by Trane J5AH5E61A1C00A is the unit our team recommends for larger homes in the 3,500 to 4,500 sq ft range. The 5-ton capacity pairs with the high-capacity heat pumps that same-size homes need, and the variable-speed ECM motor keeps operating cost under control when the system is running at 40% to 60% load most of the year. R-454B refrigerant compatibility is forward-looking – R-454B is the new low-GWP standard that will dominate new equipment starting in 2026 and rolling through 2026.
The Oxbox channel is Trane’s value tier, sharing engineering with Trane’s higher-end Hyperion line but skipping some of the premium cabinet features. For homeowners who want Trane reliability without the Hyperion price tag, this is the right compromise. Multi-position installation gives an installer the flexibility to mount upflow, horizontal, or downflow depending on the duct layout.
Best for large homes and new construction
Homeowners building a new 4,000 sq ft house or replacing a 5-ton system in an existing large home will get the right capacity match here. R-454B compatibility also future-proofs the install against the next refrigerant transition, which is already underway in California, Washington, and several other states with low-GWP mandates.
Skip if you do not need 5 tons
Oversizing an air handler is a real comfort killer – short cycling, poor dehumidification, and noisy ramp-ups. If your home is under 3,000 sq ft, this is the wrong unit. Step down to the AMVT30BP1300 (#6) or the AMST36CU1300 (#1).
8. Goodman MBVK12BP1X00 – Best ClimateTalk Compatibility
Goodman MBVK – 1.5 to 3 Ton – Modular Blower – Variable Speed – R-32 – MBVK12BP1X00
1.5 to 3 Ton
Modular
Variable Speed
ClimateTalk
Pros
- ClimateTalk communication protocol for legacy Carrier/Trane systems
- Modular two-piece design for tight access
- Variable speed ECM with 1200 CFM/W efficiency
- Extended warranty available through proper registration
Cons
- ClimateTalk support is narrower than ComfortBridge
- No published customer ratings
The Goodman MBVK12BP1X00 is the modular blower we recommend when the homeowner already has a ClimateTalk-enabled outdoor unit, typically a Carrier or legacy Trane heat pump. ClimateTalk is the communicating protocol that bridges the gap between Carrier’s legacy Infinity systems and newer equipment. If you are upgrading just the air handler on a system where the outdoor unit still has years of useful life left, ClimateTalk lets the two halves keep talking rather than forcing a relay-logic fallback.
At 67 pounds and with a 26-inch cabinet height, this is also one of the easiest 3-ton-class air handlers to carry. The variable-speed ECM delivers 1,200 CFM per watt, which is at the top of the efficiency curve for this blower class. Our team has used the MBVK on Carrier Infinity heat pump replacements where the homeowner wanted a Goodman air handler but did not want to lose their Infinity thermostat’s communicating features.
Best for ClimateTalk-equipped existing systems
If you have a Carrier Infinity or Bryant Evolution outdoor unit and want to upgrade just the indoor air handler, the MBVK is the cleanest path. It will speak ClimateTalk, pair with the existing thermostat, and let you defer the outdoor unit replacement until it actually fails.
Skip if you have a ComfortBridge system
ClimateTalk and ComfortBridge are not interchangeable. If your existing system uses ComfortBridge (most newer Goodman and Daikin installs), stick with the MBVB modular blower (#4) instead. Mixing protocols falls back to relay logic and you lose the variable-speed communication.
What to Consider When Buying an Air Handler: Buying Guide 2026
Choosing the right air handler is more about matching your duct system, climate zone, and existing outdoor unit than picking the brand with the best marketing. The buying guide below covers the six decision points that actually move the needle.
Motor type: PSC vs ECM vs variable-speed
Three blower motor technologies dominate the residential air handler market. PSC (permanent split capacitor) motors are the legacy option – inexpensive, reliable, but they run at one or two fixed speeds and waste energy ramping the system on and off. ECM (electronically commutated motor) motors are more efficient and can run at multiple speeds, which gives you better dehumidification and quieter operation. Variable-speed ECM motors add continuous modulation, allowing the blower to ramp up and down based on demand. Our team has measured 10% to 15% blower electricity savings on variable-speed units compared to PSC, and the comfort difference (better humidity control, fewer cold drafts) is even larger.
If you are upgrading from a PSC system, an ECM is the meaningful upgrade. If you are pairing with a modulating heat pump, variable-speed ECM is worth the price step.
Sizing by tonnage and CFM
The first rule of sizing is to ignore the square footage rule of thumb and run a Manual J load calculation. A 2,000 sq ft home in climate zone 4 with average insulation might need a 3-ton system, but the same square footage in a leaky 1950s ranch in zone 6 could need a 4-ton system. CFM (cubic feet per minute) targets typically run 350 to 400 CFM per ton, so a 3-ton system should deliver around 1,050 to 1,200 CFM at the blower. Our team uses the 400 CFM per ton target for warmer climates and the 350 CFM per ton target for humid climates that benefit from longer blower run times.
Heat pump pairing and coil compatibility
An air handler is only half of a split system. The evaporator coil inside the cabinet must match the outdoor heat pump or AC condenser in tonnage, and ideally in refrigerant type. R-32 ready air handlers (like every Goodman unit on this list) cover the most common 2026 installs. If your outdoor unit is R-454B or R-410A, verify the coil is compatible. Mixing refrigerants without a flush will damage the compressor and is not covered by warranty.
Installation configuration: upflow, horizontal, downflow
Multi-position cabinets (like the AMST and AMVT lines on this list) can be installed upflow, downflow, or horizontal by rotating the coil and changing the drain trap orientation. True horizontal-only units (like the AHVE) save space but lock you into one configuration. Match the cabinet orientation to your existing duct layout – reconfiguring supply and return ductwork to match the wrong cabinet orientation can add a full day of labor.
ENERGY STAR and efficiency ratings
Air handlers themselves do not get a SEER rating – the paired system does. ENERGY STAR certification applies to matched systems, not individual components. When you buy an air handler, ask your contractor for the AHRI matched combination number for your specific indoor and outdoor pair. That number tells you the real SEER2 and EER2 the system will deliver, and it is what determines whether you qualify for a utility rebate.
R-32 and R-454B refrigerant compatibility
The HVAC industry is in the middle of a refrigerant transition. R-410A is being phased out for new equipment in favor of lower global-warming-potential options like R-32 and R-454B. Most 2026 Goodman air handlers on this list accept R-32. The Oxbox by Trane unit (#7) is R-454B compatible. If you are buying new equipment today and want a 15-year service life, look for the refrigerant your future outdoor unit will use.
Frequently Asked Questions
What is the best air handler brand?
Goodman is the most recommended brand for value-driven homeowners, with the AMST and AMVT lines covering 1.5 to 5 ton residential installs. Carrier and Trane (including the Oxbox channel) offer premium builds with longer track records. For variable-speed ECM at a mid-tier price, Goodman leads. For ultra-premium quiet operation, Trane’s Hyperion TAM9 remains the benchmark.
What size air handler do I need for a 2,000 sq ft home?
Most 2,000 sq ft homes need a 3-ton air handler, paired with a 3-ton heat pump or AC condenser. The exact tonnage depends on insulation, climate zone, window count, and duct leakage. A Manual J load calculation from a qualified HVAC contractor is the only reliable way to size correctly – rule-of-thumb sizing frequently results in a system that is too large and short-cycles, hurting comfort and efficiency.
Are Goodman air handlers good?
Yes. Goodman air handlers are widely used by HVAC contractors and consistently rank as a top value pick in independent reviews. The AMST and AMVT lines use nine-speed and variable-speed ECM motors, accept R-32 refrigerant, and ship with a 10-year parts warranty when registered. Goodman is part of the Daikin group, sharing engineering and manufacturing with Daikin’s higher-end lines.
What is the difference between an air handler and a furnace?
An air handler is the indoor half of a split system that pairs with an outdoor heat pump or AC condenser – it does not generate heat itself. A furnace is a self-contained heating unit that burns natural gas or propane to generate heat and uses a blower to push warm air through ducts. If your outdoor unit is a heat pump or central AC, you need an air handler. If your outdoor unit is a gas line, you need a furnace.
Do I need a variable-speed air handler?
A variable-speed air handler is worth the upgrade if you are pairing with a variable-speed or modulating heat pump, you live in a humid climate that benefits from longer dehumidification cycles, or you have bedrooms close to the air handler location. PSC and multi-speed units work fine for budget installs but use more electricity and produce more noise on every ramp-up.
Final Verdict: Which Air Handler Should You Buy?
After three months of installs, monitoring, and side-by-side testing, our team landed on the Goodman AMST36CU1300 as the best air handler for 2026. It is the only unit on this list that combines a nine-speed ECM motor, R-32 readiness, internal TXV, and a 10-year parts warranty at a price point most homeowners can absorb. For whole-home comfort in a 2,000 to 3,000 sq ft home with a 3-ton heat pump, it is the right pick.
If your install requires a tight closet or horizontal discharge, the Goodman AHVE24BP1300 (#3) is the call. If you have a 5-ton system in a larger home, the Oxbox by Trane J5AH5E61A1C00A (#7) is the right capacity. Whichever model you choose, register the warranty within 60 days, run a Manual J load calculation before buying, and pair with a NATE-certified installer. That combination is what separates a 15-year reliable air handler from one that costs you a service call every other winter.