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Heating & Cooling Load and Building Envelope
Equipment sizing and whole-building load work: Manual J style block loads, BTU sizing, envelope conduction and infiltration…
Airflow, Fans & Ventilation
Airflow requirements per room and per ton, fan law scaling, air change rates and code-required outdoor air ventilation rates.
Psychrometrics & Air Properties
The moist-air property math behind every coil, dehumidifier and cooling tower: dew point, wet bulb, relative humidity, humidity…
Refrigerant Charging & System Diagnostics
Field calculations technicians run on every service call: superheat, subcooling, target superheat, temperature split, charge…
Hydronics, Boilers & Radiant Heat
Water-side heating design: flow rate and pump head, radiant floor loop layout, baseboard and radiator output, and boiler sizing.
Most used in hvac, refrigeration & building science
- Manual J Heating & Cooling Load CalculatorACCA Manual J 8th ed. (block load)This calculator runs a whole-house block load in the shape ACCA Manual J uses: conduction through each envelope assembly…
- Air Conditioner BTU & Tonnage CalculatorAHAM / ENERGY STAR room AC sizing methodEnter the room's floor area and this calculator returns the cooling capacity it needs in BTU per hour and in tons, using the…
- Furnace Size (BTU Input) CalculatorACCA Manual S equipment selectionA furnace is sold by its input rating and it heats your house with its output . This calculator converts the design heat loss…
- R-Value to U-Value Converter CalculatorASHRAE Fundamentals thermal resistance conventionsR-value and U-factor are reciprocals of one another, but they are quoted in different units on either side of the Atlantic and…
- Duct Size Calculator (Equal Friction & Velocity Method)ASHRAE / ACCA Manual D friction equationEnter the airflow a duct has to carry and the friction rate your design allows, and this calculator returns the round diameter…
- Available Static Pressure & Friction Rate CalculatorACCA Manual D friction rate procedureA blower produces a fixed amount of static pressure at its design airflow, and the filter, coil, humidifier, grilles and…
- Room CFM Requirement CalculatorACCA Manual D room airflowThe airflow a room needs follows from one equation: sensible load divided by 1.08 times the temperature difference between the…
- CFM per Ton CalculatorAHRI 210/240 rated airflow basisCFM per ton is the field measurement that tells you whether a cooling system is moving enough air to reach its rated capacity…
- Air Changes Per Hour (ACH) CalculatorASHRAE 62.1 / 62.2 ventilationAir changes per hour is airflow expressed as multiples of the room's own volume: 6 ACH means the fan moves six times the room's…
- Dew Point Calculator (from Temperature & RH)Magnus-Tetens with WMO coefficientsDew point is the temperature at which the air you are standing in becomes saturated, and it is the number that decides whether…
- Wet Bulb Temperature CalculatorASHRAE Handbook—Fundamentals, Ch. 1 (adiabatic saturation)Enter a dry-bulb temperature and either the relative humidity or the dew point, and this calculator returns the thermodynamic…
- Relative Humidity CalculatorASHRAE Handbook—Fundamentals, Ch. 1 (Hyland–Wexler)Enter a dry-bulb and wet-bulb reading from a sling psychrometer or a digital hygrometer and this calculator returns relative…