#hvac

Propane and LPG tank maths as an API, computed locally and deterministically — the usable-fill, energy and burn-time numbers a homeowner, RV-er, grill-master or HVAC tech works out at the tank. The tank endpoint turns a tank size into real numbers: liquid propane is 4.24 lb per gallon and holds 91,452 BTU per gallon (about 21,569 BTU per pound), so a 20 lb barbecue cylinder carries roughly 4.7 gallons and 431,000 BTU. It knows the two ways tanks are sized — a portable cylinder (20, 30, 40 lb) is rated by the propane weight it holds, while a bulk tank (100, 250, 500, 1000 gal) is filled to only 80 % of its water capacity to leave room for expansion, so a 500-gallon tank actually holds 400 gallons of propane and about 36.6 million BTU. The burntime endpoint divides that energy by an appliance’s BTU-per-hour input rating to give run time: that same 20 lb cylinder runs a 30,000 BTU/hr patio heater about 14 hours, and an optional hours-per-day turns it into days. The refill endpoint costs a fill from a price per gallon, gives the cost per 100,000 BTU so you can compare propane to natural gas or electricity, and — with an appliance rating — the running cost per hour. Everything is computed locally and deterministically, so it is instant and private. Ideal for home-energy, HVAC, RV, off-grid, grilling and outdoor-living app developers, fuel-cost and tank-monitor tools, and propane-delivery calculators. Pure local computation — no key, no third-party service, instant. US units. Live, nothing stored. 3 compute endpoints. For vehicle fuel economy or the ideal gas law use a different API.

api.oanor.com/propane-api

Moist-air (psychrometric) thermodynamics as an API, computed locally and deterministically. The dewpoint endpoint computes the dew-point temperature and the saturation and actual water-vapour pressures from a dry-bulb temperature and relative humidity, using the Magnus-Tetens relation over water, es = 6.112·exp(17.62·T/(243.12+T)) hPa — the dew point is the temperature to which air must cool for water vapour to start condensing. The humidity-ratio endpoint computes the humidity ratio (mixing ratio) W = 0.621945·Pw/(P−Pw), the specific and absolute humidity, the vapour pressure and the moist-air enthalpy h = 1.006·T + W·(2501 + 1.86·T) kJ per kg of dry air, at any total pressure (default sea-level 101325 Pa). The wet-bulb endpoint computes the wet-bulb temperature with the Stull (2011) empirical fit and the wet-bulb depression, the gap between dry- and wet-bulb that widens as the air gets drier. Temperatures are in °C, relative humidity in %, pressures in Pa. Everything is computed locally and deterministically, so it is instant and private. Ideal for HVAC, building-physics, meteorology, drying, greenhouse and data-centre-cooling app developers, comfort and condensation-risk tools, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is moist-air psychrometrics; for ASHRAE ventilation airflow use a ventilation API, for the WBGT heat-stress index a WBGT API and for the standard atmosphere an atmosphere API.

api.oanor.com/psychrometric-api

Ventilation and airflow maths as an API, computed locally and deterministically. The air-changes endpoint relates the air changes per hour, the airflow in CFM and the room volume — ACH = CFM × 60 ÷ volume — and solves whichever you leave out (the volume can be given directly or as length × width × height), reporting the airflow in cubic metres per hour too. The required-cfm endpoint applies the ASHRAE 62.1 breathing-zone rule, outdoor airflow = people × Rp + floor area × Ra, with sensible office defaults (5 CFM per person and 0.06 CFM per square foot), to size the fresh-air a space needs. The duct-velocity endpoint computes the air velocity in a round or rectangular duct from the flow and the duct size, V = CFM ÷ area, in feet per minute, metres per second and miles per hour, with guidance on whether it is in the quiet residential or noisier high-velocity range. Everything is computed locally and deterministically, so it is instant and private. Ideal for HVAC, building-services, indoor-air-quality and facilities app developers, ventilation-sizing and duct-design tools, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is ventilation and airflow; for heating and cooling load sizing use an HVAC API.

api.oanor.com/ventilation-api

Heating and cooling degree-day maths as an API, computed locally and deterministically. The daily endpoint computes the heating degree days, HDD = max(0, base − mean), and the cooling degree days, CDD = max(0, mean − base), for a single day from a base temperature and the daily mean — or the minimum and maximum, since the mean is taken as their average. The period endpoint sums the degree days over a list of daily temperatures (means or min/max pairs), returning the total HDD and CDD, the count of heating and cooling days and the average temperature — the standard way to characterise a heating or cooling season. The energy endpoint turns degree days into an energy estimate: the heat delivered is UA·DD·24/1000 kWh from the building heat-loss coefficient, the fuel or electricity input is that divided by the boiler efficiency (or a heat-pump COP), and — with an energy price — the cost. Everything is computed locally and deterministically, so it is instant and private. Ideal for building-energy, HVAC and facilities tools, heating-bill and fuel-budget estimation, weather-normalisation and energy-benchmarking apps, and engineering education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is degree-day demand estimation; for U-value and heat-loss fabric calculations use a U-value API.

api.oanor.com/degreeday-api

HVAC sizing maths as an API, computed locally and deterministically from standard rule-of-thumb factors. The cooling endpoint estimates the air-conditioner load for a room — in BTU per hour, tons of cooling and kilowatts — from the floor area (in square feet or metres, or length × width) using a baseline of about 20 BTU/h per square foot, with adjustments for the number of occupants, a kitchen, sun exposure and ceiling height. The heating endpoint estimates the heating load from the area and a climate zone (mild through very cold) or a custom BTU per square foot. The convert endpoint converts between BTU per hour, tons of cooling, kilowatts and watts (one ton = 12,000 BTU/h ≈ 3.517 kW). Everything is computed locally and deterministically, so it is instant and private. These are rule-of-thumb estimates in the EnergyStar style — a proper Manual J load calculation accounting for insulation, windows and local climate is recommended for a real installation. Ideal for HVAC and home-improvement tools, air-conditioner and heater sizing guides, smart-home and energy apps, and contractor quoting. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is HVAC sizing; for appliance running cost use an energy-cost API.

api.oanor.com/hvac-api