Air Conditioning Guides & Calculators
In-depth guides covering central AC, mini splits, portable units, sizing calculators, and more
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AC Sizing & Selection
BTU calculators and sizing guides for proper AC selection
AC Tonnage Calculator Per Square Foot (+Sizing Chart) 2026
Estimate AC tonnage by square footage, climate zone, insulation, ceilings, sun and windows, plus a sizing chart computed with the calculator's own model.
Air Conditioner BTU Calculator: What Size AC Do You Need? (2026)
Estimate a room's BTU needs from its size, climate, windows, insulation, sun, ceiling, people and appliances, cross-checked against ENERGY STAR's sizing chart.
Furnace Size Calculator: What Size Furnace Do I Need? (2026)
Estimate furnace size from your home's heat loss: square footage, insulation level, climate, ceilings, ducts and efficiency, with charts computed from the calculator's own model.
Heat Pump Size Calculator: What Size Heat Pump Do I Need? (2026)
Size a heat pump for both seasons: heating load from your home's heat loss, cooling load by climate, cold-weather capacity, balance point and backup heat.
How Many Mini Splits Do I Need? (Rooms, Zones, BTUs) 2026
How to count mini split zones for your home: one head per closed room or open area, sizing each head, single-zone vs. multi-zone outdoor units, and mistakes that cost comfort.
Mini Split Sizing Calculator: What BTU Mini Split Do I Need? (2026)
Estimate mini split head sizes room by room from square footage, room type, climate, insulation and sun, with a sizing chart computed from the calculator's own model.
Water Heater Sizing Calculator: Tank vs Tankless Sizing (2026)
Estimate your household's hot water use, then size a tank by first-hour rating or a tankless heater by flow rate. With the calculator's assumptions and running costs by type.
What Size Generator Do I Need? Appliance Wattage Calculator (2026)
Size a generator from running watts plus the largest starting surge, with the calculator's appliance wattages, worked examples, central AC guidance and CPSC carbon monoxide rules.
What Size Tankless Water Heater Do I Need? (2026 Sizing Guide)
Size a tankless water heater from flow and temperature rise: fixture flow rates, a sizing chart in BTU and kW, what gas and electric units can deliver, and worked examples.
Central Air Conditioning
Whole-home cooling systems, window units, and ductwork guides
AC Not Cooling? Causes and Fixes, From the Filter to Refrigerant (2026)
Why your AC runs but doesn't cool: the common causes, from a clogged filter to a refrigerant leak, with fixes and when to call a licensed pro.
AC Troubleshooting Guide: Fix 6 Common Problems (2026)
Whole-system AC troubleshooting: match your symptom (won't turn on, strange noise, leaking water, short-cycling, freezing, high bills) to the likely cause, and know when it's DIY vs a pro call.
Portable vs Window AC: Which Is Better? (2026 Comparison)
Portable and window air conditioners compared on cooling, efficiency ratings, running cost, noise and installation, and the situations where each one is the right choice.
Mini Split Systems
Ductless AC systems, multi-zone setups, and installation guides
AC Dry Mode Explained: What It Does & When to Use It
What dry mode does on your mini split or AC, how it differs from cool mode, when to use it, whether it saves energy, and the one moisture problem it can't fix (that's a dehumidifier's job).
What Is a Mini Split and How Does It Work? (Ductless AC Explained)
What a mini split is and how it works: the refrigeration cycle, inverter compressor, why ductless design saves energy, and when a mini split is the right choice.
Mini Split Air Conditioners: Cost, Efficiency and Installation (2026)
Mini split costs, efficiency ratings, single vs multi-zone, DIY vs professional installation, maintenance, common problems and 2026 rebates.
How Much Electricity Does a Mini Split Use? (Watts, kWh & Cost to Run)
How much electricity a mini split uses and what it costs to run: watts, kWh per month, cost by size, the low and high state rates, and how to cut both.
Mini Split Installation Cost: What to Expect (2026 Guide)
A breakdown of mini split installation costs: materials, electrical, and permits, with installed-cost estimates by system size and what DIY can and can't save.
Mini Split vs Central Air: Which Is Better? (8 Key Differences)
Side-by-side comparison of mini split vs central air on efficiency, cost, installation, zoning, aesthetics, noise, maintenance, and resale, plus a clear decision framework. Sourced to DOE and ENERGY STAR.
Portable Air Conditioners
Portable and window AC units for targeted cooling
How to Drain a Portable AC: Step-by-Step (Plus How Often)
How to drain a portable air conditioner by hand, with a continuous drain hose or a condensate pump, why some units rarely need draining, how often to drain, and how to prevent leaks and mold.
How to Vent a Portable AC Without a Window (5 Methods)
Five proven ways to vent a portable air conditioner when you don't have a standard window: sliding doors, drop ceilings, through-wall vents, dryer vents, and casement adapters, and when each one makes sense.
How Much Electricity Does a Portable AC Use? (Cost Calc)
What a portable AC costs to run by wattage, BTU size and hours, with a calculator, a full-summer total, and how it compares to window and mini-split.
Portable Air Conditioners: Sizing, Venting, Efficiency and Costs (2026 Guide)
How portable air conditioners work, single vs. dual hose, sizing by SACC, what CEER means, running costs, venting and draining, noise, and when a window unit is better.
Single-Hose vs Dual-Hose Portable AC: Which Is Better?
Single-hose vs dual-hose portable AC compared: why dual-hose is noticeably more efficient, whether portables pull outside or fresh air in, and wildfire-smoke tips.
Most Popular This Month
AC Tonnage Calculator Per Square Foot (+Sizing Chart) 2026
Estimate AC tonnage by square footage, climate zone, insulation, ceilings, sun and windows, plus a sizing chart computed with the calculator's own model.
Air Conditioner BTU Calculator: What Size AC Do You Need? (2026)
Estimate a room's BTU needs from its size, climate, windows, insulation, sun, ceiling, people and appliances, cross-checked against ENERGY STAR's sizing chart.
Furnace Size Calculator: What Size Furnace Do I Need? (2026)
Estimate furnace size from your home's heat loss: square footage, insulation level, climate, ceilings, ducts and efficiency, with charts computed from the calculator's own model.
Heat Pump Size Calculator: What Size Heat Pump Do I Need? (2026)
Size a heat pump for both seasons: heating load from your home's heat loss, cooling load by climate, cold-weather capacity, balance point and backup heat.
Mini Split Sizing Calculator: What BTU Mini Split Do I Need? (2026)
Estimate mini split head sizes room by room from square footage, room type, climate, insulation and sun, with a sizing chart computed from the calculator's own model.
Mini Split Air Conditioners: Cost, Efficiency and Installation (2026)
Mini split costs, efficiency ratings, single vs multi-zone, DIY vs professional installation, maintenance, common problems and 2026 rebates.