Engineering Hub
30 free calculators for the numbers that cost you money — the penalty on your power bill, what your boiler and generator really cost, hot water, solar, aircon sizing. Plus the full engineer's toolkit: cable sizing to BS 7671, psychrometrics, steam tables and more.
Built by Karnot engineers — 30+ years thermal engineering experience. Every constant cited to its standard.
Cable Sizing Calculator
Calculate cable cross-section, voltage drop, and breaker sizing for heat pump installations. BS 7671 / IEC 60364 compliant with derating factors for ambient temperature and installation method.
Launch CalculatorUnit Converter
Instant conversion between imperial and metric units: GPM to L/s, PSI to Bar, BTU to kW, pipe DN to NPS, and temperature scales. Real-time bidirectional conversion as you type.
Launch ConverterPower Factor Correction
Size a capacitor bank (kVAr), check the Philippine Distribution Code 85% minimum, and see the monthly peso penalty saving. IEEE Std 141 method.
Launch CalculatorHot Water Demand Sizing
Litres per day by hotel rooms, hospital beds, restaurant covers or occupants — CIBSE Guide G figures, heater kW, storage volume, and the heat pump that fits.
Launch CalculatorBoiler to Heat Pump Converter
Boiler kW, boiler HP or steam kg/h in — heat pump equivalent, yearly fuel vs electricity cost and CO₂e out. Honest about the 75°C limit.
Launch CalculatorGenset Sizing Calculator
Generator kVA per ISO 8528 with the motor-starting surge handled properly — DOL, star-delta, soft start, VFD — plus the honest diesel cost per kWh.
Launch CalculatorVoltage Drop Calculator
Volts and percent against the Philippine Electrical Code 3%/5% limits, IEC 60228 conductor data, minimum size finder, and the peso cost of cable losses.
Launch CalculatorMotor Starting Current
One motor, four starting methods side by side — DOL, star-delta, soft starter, VFD. Amps, kVA, the torque catch, and the genset impact. IEC 60034-12.
Launch CalculatorSolar Array & Battery Autonomy
Array kWp from daily kWh and Philippine sun hours; LFP battery kWh from night load and autonomy. Zero-export logic, iVOLT bundle match.
Launch CalculatorkW / kVA / Amps Converter
Enter any one — get the other two instantly, plus the running cost per day and month in pesos. The fast version of the electrical load tool.
Launch CalculatorWater Heating Cost Comparison
Same 1,000 litres, four ways: electric, LPG, diesel, heat pump — pesos per batch, day and year, with cited fuel values. LPG honestly beats electric; the heat pump beats both.
Launch CalculatorHeat Exchanger LMTD
Log mean temperature difference for counterflow and parallel exchangers, with required area from duty and U value. Kern method, typical-U table, crossing checks.
Launch CalculatorThermal Storage Sizing
Litres to kWh and back, hours of load carried, and the saving from charging heat during solar or off-peak hours. With the honest word on PCM vs water.
Launch CalculatorComfort Cooling Load (Aircon HP)
What HP aircon for your room — kW, BTU/h and Philippine market HP size from floor area, sun, people and equipment. With monthly running cost.
Launch CalculatorEnergy & Carbon Converter
Convert BTUs, Therms, LPG cylinders, diesel litres, and heating oil gallons into thermal kWh and Scope 1 CO₂e emissions. See the heat pump alternative for ESG compliance.
Launch ConverterMass Flow Rate & Pump Sizing
Calculate required pump flow rates (L/s, m³/h) and pressure drops for hydronic heating and cooling systems. Input your thermal load to get precise pipe and pump specifications.
Launch CalculatorCooling Tower Evaluator
Evaluate cooling tower performance and feed water requirements. Input wet bulb temperature, approach, and range to size your cooling tower for optimal efficiency.
Launch EvaluatorBoiler Feedwater Pre-Heat
Pre-heat your boiler make-up water with iHEAT R290 + iSTOR thermal battery. Calculate annual fuel savings, CO₂ reduction and payback for diesel, LPG, natural gas, and HFO boilers.
Launch CalculatorRefrigerant & Oil Charge
Calculate precise oil and refrigerant charges based on system pipe length, diameter, and component volume. Essential for commissioning and servicing heat pump systems.
Launch Calculator Coming SoonCold Room Load Estimator
Input room dimensions, insulation values, product load, and target temperature to calculate the required kW cooling capacity for cold rooms and freezer stores.
Launch Calculator Coming SoonThread Dimension Reference
Searchable database covering DIN, GOST, BSP, NPT, Metric, JIS, ISO, ANSI, and AFBMA thread standards. Instantly look up pitch, major/minor diameters, and tapping drill sizes.
Launch ReferencePinch Analysis Tool
Identify optimal heat recovery targets in industrial processes. Input your hot and cold stream data to find the pinch point and maximum energy recovery potential.
Launch ToolHeat Pump Sizing Calculator
Calculate building heat loss per BS EN 12831 / ASHRAE, size a Karnot heat pump (R-290 or CO₂), and compare annual running costs and CO₂ savings vs gas, oil, or electric heating.
Launch CalculatorOffice Cooling Load Calculator
ASHRAE-style cooling load — fabric, ventilation, occupants, equipment, lighting, solar gain. Sensible + latent split. Catches the dense-occupancy / hot-climate cases that simple W/m² rules of thumb miss.
Launch CalculatorPFAS & Refrigerant Carbon
Calculate CO₂e impact of refrigerant leaks and PFAS exposure. See your Scope 1 liability under SEC PFRS S2 and compare natural vs synthetic refrigerant options.
Launch CalculatorRA 11285 Classification
Determine your facility's tier under the Energy Efficiency & Conservation Act. Tells you whether you need a CECO/CEM, mandatory audits and DEOS portal reporting.
Launch CalculatorSEC PFRS S2 Carbon & F-Gas
Scope 1 + Scope 2 carbon converter including the refrigerant-leak F-gas liability most companies under-report. Built for SEC sustainability disclosures.
Launch CalculatorHotel Retrofit Quick Sizer
Public sales-grade sizer. Rooms in, savings out. Models DHW + pool + laundry, recommends iHEAT system, computes Buy vs Rent (EaaS) economics.
Launch CalculatorRefrigerant Properties
Look up saturation pressure, density, enthalpy, and latent heat for R290, CO₂, R32, R410A, and R134a. ASHRAE reference data with real-time interpolation.
Launch CalculatorPsychrometrics Calculator
Calculate wet bulb, dew point, enthalpy, and specific humidity from any two inputs. Includes interactive psychrometric chart with live state point plotting.
Launch CalculatorWater & Steam Properties
IAPWS-IF97 steam tables: look up saturation pressure, density, enthalpy, latent heat, and specific heat for water and steam from 0°C to 374°C.
Launch CalculatorPipe Sizing Calculator
Select optimal pipe diameter based on flow rate, velocity limits, and pressure drop. Covers copper, steel, CPVC, and stainless steel with Reynolds number analysis.
Launch CalculatorInsulation Thickness
Calculate minimum insulation thickness for heat conservation or condensation prevention. Supports Armaflex, Rockwool, Foam Glass, PIR, and custom materials.
Launch CalculatorCondensate Return & Flash Steam
Calculate flash steam generation, heat recovery potential, and recommended return pipe sizing. See the iHEAT heat recovery opportunity for your condensate system.
Launch CalculatorElectrical Load Calculator
Calculate current draw, apparent power (kVA), reactive power (kVAr), power factor correction, and MCB/fuse sizing for single and three-phase electrical loads.
Launch CalculatorHot Water OPEX Calculator
Compare annual hot water costs: electric resistance, LPG boiler, and Karnot iHEAT heat pump. Enter your demand and local rates to see exact savings in Philippine pesos.
Launch CalculatorHotel Retrofit Calculator
Calculate your hotel's true hot water costs including the Legionella penalty, peak demand charges, and laundry/kitchen loads. Compare CAPEX vs EaaS.
Launch CalculatorBoiler Energy Flow Analyser
See exactly where your steam boiler loses energy. Model coil, sparging, and heat pump scenarios with interactive Sankey diagrams and live cost comparison.
Launch AnalyserCold Chain Energy Flow Analyser
Compare HFC electric defrost, ammonia, and Karnot iCOOL CO₂ + FLX Flex Defrost side by side. Model your cold store — see where energy goes and calculate savings.
Launch AnalyserPool Heat Pump Sizing
Enter pool dimensions, climate, and location to get an instant iSPA model recommendation with estimated monthly running costs. Multi-currency support.
Launch CalculatorPool Heat Pump Retrofit
Drop-in replace aging Pentair, Hayward, or generic R410A pool heat pumps with Karnot iSPA R32 inverters. Full Scope 1 + Scope 2 carbon accounting for ESG-led condos and commercial pools.
Launch CalculatoriVOLT Solar + Heat Pump Sizing
Full engineering calculator: size your solar array, add optional heat pump for hot water, calculate savings, payback, and get an iVOLT bundle recommendation. Multi-currency.
Launch CalculatorFrequently Asked Questions
What engineering tools are available in the Karnot Engineering Hub?
The Karnot Engineering Hub provides 30 free tools: electrical cable sizing (BS 7671/IEC 60364), voltage drop (Philippine Electrical Code), electrical load (kW/kVA), power factor correction with peso penalty savings, kW/kVA/amps converter, motor starting current, genset sizing (ISO 8528), solar array & battery autonomy, unit conversion, energy & carbon converter, mass flow rate & pump sizing, heat pump sizing, hot water demand sizing (CIBSE Guide G), water heating cost comparison, boiler to heat pump converter, heat exchanger LMTD, thermal storage sizing, comfort cooling load (aircon HP), pinch analysis, cooling tower evaluator, pipe sizing, insulation thickness, condensate return & flash steam, PFAS & refrigerant carbon, refrigerant properties (R290/CO₂/R32/R410A/R134a), psychrometrics with chart, water & steam properties (IAPWS-IF97), and thread dimension reference.
Are these engineering calculators free to use?
Yes, all calculators in the Karnot Engineering Hub are completely free with no login required. They are built by our engineering team to help HVAC, refrigeration, and mechanical professionals with daily calculations.
What standards do the calculators follow?
Our calculators follow international standards and cite them on each page: BS 7671 (IET Wiring Regulations), IEC 60364, IEC 60228 conductor data, the Philippine Electrical Code voltage drop limits, the Philippine Distribution Code 85% power factor rule, IEEE Std 141, ISO 8528-1 generator ratings, IEC 60034-12 motor starting, CIBSE Guide G hot water demands, ASHRAE reference data, and DIN, ISO, BSP, NPT, JIS, and ANSI thread specifications.
Can I use these calculators for heat pump installations?
Absolutely. The cable sizing calculator includes quick-select buttons for common Karnot heat pump power ratings (9.5kW to 100kW), and the unit converter covers all flow, pressure, energy, and temperature conversions needed for heat pump system design.
What refrigerant data is available?
The Refrigerant Properties calculator provides ASHRAE-reference saturation tables for R290 (propane), CO₂ (R744), R32, R410A, and R134a — including pressure, density, enthalpy, latent heat, and specific heat at any temperature. The PFAS & Refrigerant Carbon calculator shows the CO₂e impact of refrigerant leaks and PFAS classification for Scope 1 reporting under SEC PFRS S2.
Do you have psychrometric and steam table tools?
Yes. The Psychrometrics calculator computes wet bulb, dew point, enthalpy, and specific humidity from any two inputs, with an interactive psychrometric chart. The Water & Steam Properties calculator provides IAPWS-IF97 saturation tables from 0°C to 374°C including pressure, density, enthalpy, latent heat, and specific heat.
Do you have energy flow Sankey tools?
Yes — the free Boiler Energy Flow Analyser shows exactly where steam boiler energy is lost across diesel, electric, and LPG scenarios with live cost comparison against Karnot iHEAT R290. The Cold Chain Energy Flow Analyser compares HFC electric defrost, ammonia, and Karnot iCOOL CO₂ + FLX Flex Defrost with interactive Sankey diagrams and savings calculations.
What are the Advanced Engineering Calculators?
The Advanced Calculator Suite includes professional sizing and analysis tools: Heat Pump Sizing, Cold Room Load Estimator, Steam Boiler Replacement ROI, Pinch Analysis, Boiler and Cold Chain Energy Flow Analysers, Refrigerant & Oil Charge, and Cooling Tower Evaluator. Free access — one-time registration with your name, email and company required. Access Advanced Tools →
Is there a refrigerant carbon calculator?
Yes — the PFAS & Refrigerant Carbon Calculator shows your CO₂e Scope 1 liability from refrigerant leaks and compares HFC vs natural refrigerant options for SEC PFRS S2 compliance. It covers R290, CO₂, R32, R410A, R134a, R404A, R407C, and R22 with GWP, PFAS classification, and carbon tax estimates.
Need Custom Engineering Support?
Our engineering team can provide bespoke sizing, system design, and commissioning support for your heat pump project.