HVAC calculators and reference tables

32 calculators and 16 reference tables for the van and the mechanical room: superheat and subcooling, airflow and duct sizing, wire and motor data, combustion and gas, psychrometrics, walk-in load, and pressure-temperature charts for 48 refrigerants. Free, and the same tools are in the app offline.

Calculators: Refrigeration

Superheat (fixed orifice / cap tube)Actual superheat and the target from the outdoor and indoor temperaturesSubcooling (TXV systems)Subcooling from the head pressure and the liquid line tempRecovery cylinder max fillThe 80% rule: how much refrigerant a cylinder may holdVacuum pump sizePump size and vacuum targets by system sizeVacuum decay testLeak or moisture? Read the micron rise after isolating the pumpWalk-in cooler / freezer loadWall, door-air, product and extra heat loads; suggested capacityDefrost heater energykWh and heat added per day from the defrost cycles

Calculators: Airflow & ducts

Airflow & heating outputcfm, temperature rise, output and cooling airflowStatic pressure & friction rateAvailable static pressure and the friction rate for duct designRound duct sizeDuct diameter from the airflow and the friction rateRound ⇄ rectangular ductEquivalent sizes with the same frictionVentilation & air changescfm for people or air changes, ACH from airflow, blower-door ACH50Fan lawsWhat happens to pressure and power when the airflow changesPsychrometricsWet-bulb, humidity, dew point, grains and enthalpy from two readings

Calculators: Electrical

Ohm's & Watt's lawVolts, amps, ohms and watts: enter any twoWire run voltage dropVoltage lost in a copper wire run, by gauge and lengthMotor speed & polesSynchronous speed and expected full-load speedBelt & pulley speedDriven speed, and the pulley size you need24 V transformer loadVA to amps, and the health of the control circuitCapacitor helperReplacement size, parallel total and hard-start sizingPower factorApparent power, true power and power factor of a motorCompressor terminals (C, S, R)Find common, start and run from three ohm readings

Calculators: Heating

Combustion analysisNet stack temperature, efficiency and what the readings meanGas flow & combustion airGas volume from the BTU/h input and the air it needsElectric heat: kW, BTU/h & ampsConvert an element size and find the current and breakerQuick heat lossWall, window or roof loss, and air leakage loadPipe expansionHow much a hot water pipe grows when it heats upDegree daysHeating or cooling degree days from the daily high and lowWall R-value & U-valueAdd up layers; get R, U and heat flow through the wall

Calculators: Conversions

Temperature converter°F, °C, kelvin and RankinePressure & vacuum converterpsi, in. Hg, microns, kPa, bar, in. WCTons, BTU/h & kWCooling and heating capacity converter

Reference tables: Refrigerants

Refrigerant dataData sheet for every refrigerant: pressures, safety, GWP, oil, usesPressure & vacuum tablesVacuum, psi and kPa tables, water boiling point, altitude, refrigerant pressures in every unitLeak test, vacuum & equipment limitsTest pressures, vacuum targets, gauge ratings and recovery rulesP/T chartsPressure / temperature chart for every refrigerant — pick one

Reference tables: Electrical

Wire & circuit dataCopper wire sizes, voltages, colours and voltage limitsMotor dataSpeeds, efficiency, fuses, code letters, insulation and motor typesCompressor electrical valuesWinding resistance, power, megger readings and replacement rulesPressure & temperature controlsCut-out settings, adjustment directions, differentials and control signalsThermostat & board terminalsTerminal letters, check voltages and abbreviations on ignition boards

Reference tables: Air & ducts

Duct & airflow dataAir speeds, duct metal gauges, pressure drops, air density and leakage limitsComfort, humidity & air qualityMERV ratings, comfort ranges, dew points, recommended humidity, CO exposure

Reference tables: Building

Building & insulation valuesR-values, U-values, internal gains, solar gain and air leakage

Reference tables: Heating

Gas appliance dataCombustion targets, flames, gas properties, furnace classes and ventingBoiler & oil burner dataBoiler temperatures, expansion tanks, glycol, water limits and oil burner numbersHeat pump dataDefrost, balance point, reversing valve, charging conditions and installation

Reference tables: Small systems

Fridge, freezer & room A/C dataNormal readings, drier and cap tube sizes, bench-test temperatures

Refrigerants: P/T chart and data for 48

R-410AR-32 / R-125R-22ChlorodifluoromethaneR-134aTetrafluoroethaneR-404AR-125 / R-143a / R-134aR-407CR-32 / R-125 / R-134aR-32DifluoromethaneR-454BR-32 / R-1234yfR-448AR-32 / R-125 / R-134a / R-1234ze(E) / R-1234yfR-449AR-32 / R-125 / R-1234yf / R-134aR-507AR-125 / R-143aR-290PropaneR-600aIsobutaneR-744Carbon dioxideR-717AmmoniaR-12DichlorodifluoromethaneR-11TrichlorofluoromethaneR-123DichlorotrifluoroethaneR-23TrifluoromethaneR-125PentafluoroethaneR-143aTrifluoroethaneR-152aDifluoroethaneR-245faPentafluoropropaneR-1233zd(E)ChlorotrifluoropropeneR-1234yfTetrafluoropropeneR-1234ze(E)trans-TetrafluoropropeneR-170EthaneR-600ButaneR-1270PropyleneR-401AR-22 / R-152a / R-124R-401BR-22 / R-152a / R-124R-407AR-32 / R-125 / R-134aR-407FR-32 / R-125 / R-134aR-408AR-125 / R-143a / R-22R-409AR-22 / R-124 / R-142bR-417AR-125 / R-134a / R-600R-422AR-125 / R-134a / R-600aR-422DR-125 / R-134a / R-600aR-427AR-32 / R-125 / R-143a / R-134aR-450AR-134a / R-1234ze(E)R-452AR-32 / R-125 / R-1234yfR-452BR-32 / R-125 / R-1234yfR-454AR-32 / R-1234yfR-454CR-32 / R-1234yfR-455AR-32 / R-1234yf / R-744R-500R-12 / R-152aR-502R-22 / R-115R-508BR-23 / R-116R-513AR-1234yf / R-134a

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Calculation aids and reference figures for licensed technicians. Always follow the manufacturer’s data plate and manual for the exact model, and local codes. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Pressures are typical saturation values and change with load and airflow.