DUCTTHREE SYSTEMS. ONE LOAD.
CHOOSE YOUR ARGUMENT.
Ranked by forum member sentiment across 4,200+ threads. SEER2 ratings reflect 2025 DOE standards.
Ductless Mini-Split
Mitsubishi · Daikin · MRCOOL
- +No duct losses (20–30% energy saved)
- +Zone control per room
- +Inverter tech = no short cycling
- +Viable to −13°F on top models
- −Higher upfront cost per zone
- −Head units visible in rooms
- −A2L refrigerant transition underway
"Mitsubishi hyper-heat held 100% capacity at 5°F last January. The old Carrier gave up at 25°F."
— cold_climate_rick · 847 rep
Air-Source Heat Pump
Carrier · Trane · Lennox
- +Uses existing ductwork
- +Federal tax credit 30% / $2K
- +Single outdoor unit
- +Good cold-weather performance on modern units
- −Duct losses still apply
- −Performance drops below 0°F on older models
- −Requires compatible air handler
"Carrier Infinity 26 in Zone 5. Customer's gas bill dropped $180/month. ROI in 4 years."
— service_tech_ohio · 1.2k rep
Central AC + Gas Furnace
Goodman · Rheem · American Standard
- +Lowest upfront installed cost
- +Familiar to all techs
- +Parts widely available
- +Gas backup reliable in extreme cold
- −Highest long-term operating cost
- −R-410A phase-out affects service costs
- −Duct leakage reduces efficiency 20–30%
"Still the right call on tight budgets. Just seal the ducts or you're throwing money into the attic."
— shop_owner_dallas · 2.1k rep
Production of R-410A equipment ended Jan 1, 2025. R-454B (A2L — mildly flammable) is the replacement. Requires updated certifications, new tooling, and ventilation protocols. Service costs on R-410A systems will rise as supply contracts. Read the thread →
THE ARGUMENT IS
ALREADY HAPPENING.
R-454B in the field: anyone actually certified yet? Sharing my A2L transition notes
Finally got through the ESCO certification last week. The A2L handling is genuinely different — leak detection requirements, ventilation minimums, the whole deal. Here's what actually matters vs. what's just paperwork...
Manual J vs rule-of-thumb: contractor oversized my neighbor's unit by 1.5 tons. Here's the receipts.
Pulled the install invoice. 4-ton unit in a 1,800 sqft Zone 4 house with good insulation. Manual J comes out to 2.5 tons. Customer's been complaining about humidity since day one and I finally showed them why...
Duplex remodel: mini-splits vs conventional. Owner wants a number by Friday.
1,100 sqft per unit, Zone 5, existing gas service. Owner is asking me to bid both options. Running the numbers on a 2-zone Mitsubishi vs a standard 2.5-ton heat pump. The delta in operating cost might close the gap on install cost in...
TXV failure in August — 110°F attic, 3 callbacks. How I finally nailed it.
Third callback on a 3-year-old Carrier. Subcooling was all over the place, superheat inconsistent. Checked the TXV bulb position twice. The actual problem was...
Worst ductwork you've ever ripped out. I'll start. [Photo thread]
Found this in a 1978 ranch house. Fiberglass flex duct, 90° bends every 18 inches, all of it disconnected at the plenum. Homeowner said the upstairs was 'always a little warm.' I measured 38°F temp split...
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