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Tons and BTU/hr for a house from its floor area, climate zone, insulation, sun, windows and occupants. See the full page.

BTU/hr, tons, kW, watts, kcal/h and the Asian "horsepower" class, converted in one table. See the full page.

The BTU/hr a room unit needs from the ENERGY STAR chart, the nearest size sold and its electrical draw. See the full page.

Real cooling needed (SACC) and the ASHRAE label to look for, single or dual hose. See the full page.

BTU/hr and head size for up to five zones, and the outdoor unit that serves them. See the full page.

The cooling load that computers, appliances, lighting and people add to a room, in BTU/hr and tons. See the full page.

What an air conditioner costs per hour, day and month from its size, SEER2, run time and your electricity price. See the full page.

Electricity and dollars saved by a higher SEER2 rating, and how long the extra cost takes to pay back. See the full page.

Heating load in BTU/hr and the furnace input to buy, from floor area, climate zone, insulation and AFUE. See the full page.

Tons for cooling and heating, capacity at your design temperature, balance point and backup heat. See the full page.

Boiler output and input from the radiators or the house, with the hot-water and pickup allowances shown. See the full page.

BTU/hr and watts from a panel, column or cast-iron radiator at your water temperature, and the room it heats. See the full page.

Watts and feet of electric or hot-water baseboard a room needs, with the circuit current for information. See the full page.

Watts and BTU for a space heater as supplemental or primary heat, and the nearest size sold. See the full page.

BTU/hr a heated floor delivers at a surface temperature, whether it covers the room, and the water temperature needed. See the full page.

Heat rates in BTU/hr, MBH, watts, kW, tons, therms per hour and boiler horsepower, plus the energy over a run. See the full page.

A season of heating priced for gas, propane, oil, heat pump, electric, pellets and wood, cheapest first, with cost per million BTU. See the full page.

Splits the system airflow between up to eight rooms by area and exposure, with registers per room. See the full page.

Round and rectangular duct size for an airflow at a friction rate, checked against the velocity limit. See the full page.

Air speed in a round or rectangular duct, its friction rate, and how it compares with residential limits. See the full page.

Free area and nominal size of the return grilles for a system airflow at a quiet face velocity. See the full page.

Floor, ceiling or sidewall register size and count for a room's airflow at a target face velocity. See the full page.

Total equivalent length of a duct run with its fittings, the available static pressure and the design friction rate. See the full page.

ACH from a room's airflow, or the CFM for a target ACH, against common ventilation and exhaust targets. See the full page.

Fan CFM from the code minimum, the HVI area or fixture rule and 8 air changes, with the duct run checked. See the full page.

Hood airflow from the burner BTU and hood width rules, the makeup-air threshold and the duct run. See the full page.

The continuous outdoor air a house needs under ASHRAE 62.2 from its area and bedrooms, continuous or cycled. See the full page.

Pints per day for a basement or room from its area and dampness under the 2019 rating, with the energy to run it. See the full page.

Gallons per day a humidifier must add to hold a winter humidity, from the house volume, tightness and outdoor temperature. See the full page.

The recovery ventilator size for a ventilation rate, ERV or HRV for your climate, and the heat it recovers. See the full page.

The clean air delivery rate a room needs by the AHAM 2/3 rule or a target of 4 to 6 air changes per hour. See the full page.

Blade span for the room and the downrod for the ceiling height, with typical airflow and clearances. See the full page.

Fan CFM by the 2 to 3 CFM per sq ft or 15 to 20 ACH rules, the attic vent area it needs and the windows to open. See the full page.

Cost per hour, day and month for an air conditioner, furnace, heat pump or electric heat from its output and rating. See the full page.

A season of heating with a heat pump against a gas, propane or oil furnace, with backup heat and the break-even price. See the full page.

What lowering the thermostat at night or while out saves a season, with the heat pump caveat and the thermostat payback. See the full page.

A season of heating fuel from the design heat loss and heating degree days, with the fuel per degree day to check bills. See the full page.

Gas, propane, oil, electricity, heat pump, pellets and wood ranked by the cost of a million BTU of heat delivered. See the full page.

How often to change the furnace filter for its thickness, pets and allergies, and what a year of filters costs. See the full page.

Annual saving, payback and net gain of a more efficient furnace, boiler, AC, heat pump or water heater, after rebates. See the full page.

What leaky ducts in an attic, crawl space or basement cost a year, and the payback of sealing them. See the full page.

A sourced price range for replacing a central AC, furnace, both, or a heat pump by size, efficiency tier, ducts and region. See the full page.

Installed cost of a ductless system by number of heads, head size and type, line set, electrical work and region. See the full page.

Installed cost of a gas, propane, oil or electric furnace by size and efficiency, with venting, gas line and permit. See the full page.

Installed cost of a ducted, cold-climate or whole-house ductless heat pump, with electrical and duct work, after rebates. See the full page.

Installed cost of new ductwork per foot and for the house, flex or sheet metal, by access and region. See the full page.

Typical cost of common AC repairs, from capacitors to compressors, with the repair-or-replace rules applied. See the full page.

A year of tune-ups, filters and repairs paid as you go against a maintenance plan, and which is cheaper. See the full page.

Peak-hour hot water demand by the DOE method and the gas, electric or heat pump tank whose first-hour rating covers it. See the full page.

GPM for the fixtures running at once, the temperature rise from your groundwater, and the gas BTU or electric kW needed. See the full page.

Gallons of hot water a household uses a day from showers, baths, dishes and laundry, and the energy to heat it. See the full page.

What a gas, propane, electric, tankless or heat pump water heater costs a day, month and year for your hot water use. See the full page.

How long a tank takes to reheat and how many gallons an hour it recovers, from its size, burner or element and the rise. See the full page.

Installed cost of a gas, electric, tankless or heat pump water heater, with conversion work, permit and rebates. See the full page.

Groups up to eight rooms into zones by floor, use and exposure, with the airflow each zone needs and the warnings that matter. See the full page.

The replacement window for an AC, heat pump, furnace, boiler or water heater from its install date, conditions and repairs. See the full page.

Compares an installed air conditioner or furnace with the house's estimated load and the symptoms of over- and undersizing. See the full page.

Dew point and comfort band from temperature and humidity, and whether a window, pipe or wall will condense. See the full page.

How hot it feels from temperature and humidity by the NOAA formula, with the National Weather Service caution bands. See the full page.

BTU/hr lost through up to five walls, windows, ceilings, doors and floors from their area and R-value, and each one's share. See the full page.

Running and starting watts for an air conditioner or heat pump with the blower and other loads, and the generator to buy. See the full page.