Free HVAC Calculators for Air Conditioning Technicians
Free HVAC calculators for Australian air conditioning, refrigeration and BMS technicians. Use these tools for airflow, capacity, water flow, duct velocity, superheat, subcooling, electrical checks and common HVAC unit conversions.
How to Use These HVAC Calculators
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These HVAC calculators are designed to help technicians complete quick field checks during service, commissioning, maintenance and fault finding. The results can be used as a guide when checking air conditioning performance, chilled water systems, heating water systems, duct airflow, electrical load and refrigeration measurements.
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Airflow and airside capacity calculations
The airside cooling and heating calculator estimates sensible capacity from airflow and temperature difference. This is useful when checking whether an air handling unit, fan coil unit, package unit or ducted system is moving enough air across the coil. If the calculated kW is lower than expected, check airflow, filters, coil condition, fan speed, dampers, belt condition, VSD output and BMS control signals.
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Water flow and water-side capacity calculations
The water-side calculators estimate heating or cooling capacity from water flow and temperature difference. These checks are useful on chilled water coils, heating hot water coils, chillers, boilers, heat exchangers and pump systems. Low water-side capacity may indicate low flow, blocked strainers, incorrect valve position, air in the system, pump issues, incorrect setpoints or control valve problems.
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Superheat and subcooling calculations
The superheat and subcooling calculator helps technicians compare measured pipe temperatures against evaporating and condensing saturation temperatures. These values are useful when checking refrigerant charge, expansion valve operation, evaporator load, condenser performance and possible restrictions. Always confirm expected values against the correct manufacturer data and the operating conditions at the time of testing.
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Duct velocity and air changes per hour
The duct velocity and air changes calculators can be used for quick checks on ductwork, grilles, ventilation systems, exhaust systems and outside-air systems. High velocity can cause noise, pressure drop and comfort issues. Low velocity may indicate poor airflow, fan issues, blocked filters, closed dampers or incorrect balancing.
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Electrical and efficiency checks
The three-phase electrical calculator estimates kW and kVA from voltage, current and power factor. The COP, EER and kW per ton calculator can help compare equipment output against electrical input. These results are estimates only and should be confirmed using suitable test equipment, safe electrical procedures and manufacturer data.
HVAC Calculator FAQs
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What is an HVAC calculator used for?
An HVAC calculator helps technicians quickly estimate common air conditioning, refrigeration and mechanical service values. These may include airflow, cooling capacity, heating capacity, chilled water flow, heating water flow, duct velocity, superheat, subcooling, pressure conversion, electrical load and system efficiency.
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Can these calculators be used for commissioning?
Yes, these calculators can be used as practical commissioning aids. They are useful for checking measured site values against expected system performance. Final commissioning results should always be confirmed against manufacturer data, approved design documents, commissioning sheets and site-specific requirements.
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What is the formula for airside cooling capacity?
A common sensible airside cooling capacity formula is:
kW = 1.2 × airflow in L/s × temperature difference ÷ 1000
This gives an estimated sensible cooling or heating capacity. It does not include latent cooling, moisture removal or detailed psychrometric conditions.
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What is the formula for water-side heating or cooling capacity?
A common water-side capacity formula is:
kW = 4.186 × water flow in L/s × temperature difference
This is often used for chilled water systems, heating hot water systems, coils, chillers, boilers and heat exchangers.
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Are these HVAC calculations exact?
No. These calculators are designed as practical field tools. Actual system performance depends on site conditions, equipment selection, airflow, water flow, refrigerant condition, sensor accuracy, control strategy, valve position, pump operation and manufacturer requirements.
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Why are HVAC calculators useful for technicians?
HVAC calculators help technicians make faster decisions on site. They can assist with identifying low airflow, poor heat transfer, incorrect water flow, high duct velocity, refrigerant charge issues, electrical load concerns and inefficient equipment operation.
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Should calculator results replace manufacturer data?
No. Calculator results should be used as a guide only. Manufacturer data, design documentation, approved commissioning values and safe trade practices should always take priority.