HVAC & Energy calculators
Choose a task below. Check each calculator’s assumptions and units before using its result.
Free Window Overhang Solar Shading Calculator
Calculate seasonal sun angles and passive solar window overhang dimensions.
Free Window Tint & Solar Heat Gain Calculator
Calculate rejected heat in BTU/hr, cooling kilowatt-hours saved, annual utility cost reduction, and glare reduction percentage for architectural window films.
Free Wire Gauge & Voltage Drop Calculator
Determine circuit voltage loss, conductor heating, and the ideal AWG or mm² wire size for DC solar, automotive, and AC mains runs.
Furnace Temperature Rise Calculator - Airflow CFM & BTU
Verify furnace airflow CFM and supply-to-return temperature rise against manufacturer nameplate rating plates.
Geothermal GSHP Vertical Borehole Field Sizing Calculator
Model closed-loop vertical ground heat exchangers (GHEX), calculate borehole footage per ton, evaluate grout thermal resistance, and balance annual ground loads.
Hot Water Recirculation Loop & Pump Sizing Calculator
Calculate DHW recirculation flow rate ($Q = Q_{loss} / [500 cdot Delta T]$), total piping heat loss, Hazen-Williams friction head, and keep flow velocity below $4.0 ext{ ft/s}$ to prevent copper erosion.
Hydraulic Separator & Low-Loss Header Sizing Calculator
Size low-loss headers and hydraulic separators for primary-secondary hydronic systems. Calculate barrel diameter for $V \le 0.5\text{ ft/s}$ velocity, nozzle spacing, and thermal mixing.
Hydronic Direct vs Reverse-Return (Tichelmann) Balancing
Compare Direct-Return and Reverse-Return (Tichelmann) multi-coil distribution systems. Calculate loop lengths, branch head loss differences, and balancing valve authority.
Hydronic Expansion Tank Sizing Calculator - ASME Volume
Size ASME Section VIII diaphragm and bladder expansion tanks for closed-loop hydronic heating and chilled water HVAC piping systems.
Hydronic Glycol Freeze & Burst Protection Calculator
Determine exact Propylene/Ethylene glycol concentrations, verify optical refractometer Brix (°Bx) field tests, and calculate GPM flow derating and pump head penalties.
Hydronic Radiator Heat Output & Delta T Correction
Calculate radiator thermal output derating for heat pump lower flow temperatures (ΔT30/ΔT20) vs traditional boiler benchmarks (ΔT50/ΔT60) using EN 442 exponent equations.
Inverter DC AC Ratio Calculator - Solar Clipping Margin
Determine Inverter Loading Ratio (ILR), peak solar clipping hours, annual generation profile, and economic array oversizing balance.
M-Cycle Indirect Evaporative Cooler Calculator
Model Maisotsenko thermodynamic cycle heat exchangers, evaluate sub-wet-bulb sensible cooling with zero added moisture, and compute ultra-high EERs.
Pipe Insulation Thickness & Dew Point Condensation
Calculate minimum pipe insulation thickness to prevent surface sweating, condensation mold damage, and thermal heat gain according to ASTM C680 heat transfer equations.
Plumbing Vent Pipe Sizing & DFU Developed Length Calculator
Size plumbing atmospheric vent pipes and roof stacks per IPC/UPC tables using Drainage Fixture Units (DFU), soil stack diameter, and developed length.
Primary-Secondary Pumping & Closely Spaced Tees Calculator
Size closely spaced decoupling tees ($S le 4D$), calculate common bridge pipe fluid velocity, verify hydraulic isolation ($Delta P approx 0$), and compute blended secondary water temperatures.
Radiant Floor Heating Tube Spacing & Heat Output Calculator
Determine PEX tubing length, center-to-center spacing, manifold loop count, and water flow rate (GPM) for in-floor hydronic heating.
Radiator BTU Calculator - Room Heating & Sizing Guide
Calculate heat loss in BTUs and Watts for any room based on dimensions, window exposure, insulation levels, and exterior walls.
Septic Tank & Absorption Drainfield Trench Sizing Calculator
Size residential septic tanks and leach fields using EPA soil percolation loading rates ($GPD/ft^2$), trench bottom geometry, and bedroom design flows.
Solar Battery Bank Calculator - Amp Hours & Days Autonomy
Determine required battery bank capacity in Amp-Hours (Ah) and kWh based on daily electrical loads, autonomy reserve days, and chemistry depth of discharge.
Solar Battery Bank Calculator - Amp Hours & Storage Size
Determine total kilowatt-hour capacity, Amp-hours, days of cloud autonomy, and parallel battery string counts for off-grid cabins and RVs.
Solar Panel Tilt Angle Calculator - Latitude Optimum
Determine optimal annual, winter, and summer panel tilt angles, true South azimuth, and minimum inter-row spacing to prevent winter shading.
Solar String Voltage Calculator - Voc Cold Temp Inverter
Calculate cold-weather maximum open circuit voltage (Voc), minimum MPPT voltage at summer cell heat, and series panel limits per NEC 690.7.
Solar Wire Size Calculator - DC Voltage Drop & Gauge AWG
Determine required AWG wire gauge, DC voltage drop percentage, and power loss watts over long wire runs per NEC 690 standards.
Steam Pipe Sizing Calculator - Velocity & Pressure Drop
Determine internal pipe diameter, steam flow velocity (ft/min), and frictional pressure loss per 100 feet for saturated and superheated steam headers.
Steam Trap Orifice Sizing & Condensate Capacity Calculator
Size steam trap discharge orifices, apply application-specific warmup safety factors, compute return line flash steam percentages, and quantify dollar loss from failed-open traps.
Superheat & Subcooling Calculator - HVAC Charging & TXV
Determine actual vs target superheat and subcooling for TXV and fixed-orifice piston HVAC systems.
Venturi Scrubber Throat Velocity & Pressure Drop Calculator
Model industrial air pollution control venturi scrubbers, calculate throat velocities, evaluate Hesketh pressure drops, and determine PM2.5 capture efficiencies.
VRF / VRV Piping Equivalent Length & Additional Refrigerant
Calculate commercial VRF/VRV liquid line equivalent length, vertical lift derating, oil trap requirements, and factory top-up refrigerant charge (R410A / R32).
Water-Side Economizer Plate Heat Exchanger Calculator
Size plate-and-frame heat exchangers for water-side economizers, calculate LMTD approach temperatures, and quantify annual kWh and dollars saved by shutting off electric chillers.