BTU / ton / kW / watt
API · /hvac-api
HVAC BTU Calculator API
healthy
4,645 Subscribers
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
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 78 ms
- Server probes · 24h
- Subscribers
- 4,645
- active
- Total calls
- 80
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 11,235 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- 11,235 calls/month
- 2 req/sec
- Cooling + heating + convert
- No credit card
Starter
€12.75 /month
- 20,850 calls / month
- 8 requests / second
- Hard cap (429 above quota, no overage)
- 20.85k calls/month
- 8 req/sec
- Occupant / sun / ceiling factors
- Email support
Pro
€32.65 /month
- 258,500 calls / month
- 20 requests / second
- Hard cap (429 above quota, no overage)
- 258.5k calls/month
- 20 req/sec
- HVAC / quoting pipelines
- Priority support
Mega
€70.65 /month
- 1,335,000 calls / month
- 50 requests / second
- Hard cap (429 above quota, no overage)
- 1.335M calls/month
- 50 req/sec
- Platform scale
- Dedicated SLA
Built by
Related APIs
Other APIs with overlapping tags.
HVAC Air-Side Load API
HVAC air-side heat maths as an API, computed locally and deterministically with the classic standard-air factors — the sensible, latent and airflow numbers a mechanical engineer or HVAC technician sizes ducts and equipment with. The sensible endpoint gives the sensible heat an airflow carries to change temperature: Qs = 1.08 × CFM × ΔT (dry-bulb difference), where the 1.08 bundles standard-air density and specific heat — 2,000 CFM across a 20 °F difference is 43,200 BTU/hr, 3.6 tons — with the result in BTU/hr, tons and kW. The latent endpoint gives the latent (moisture) heat: Ql = 0.68 × CFM × ΔW, where ΔW is the humidity-ratio difference in grains of water per pound of dry air, the dehumidification part of a cooling load that runs high in humid climates and from people and cooking, and why air conditioners are sized on total, not just temperature. The airflow endpoint inverts the sensible relation: CFM = sensible load ÷ (1.08 × ΔT), the supply air needed at a chosen supply-to-room temperature difference (comfort cooling runs ~18–22 °F below room), the number that sets fan and duct size — sanity-checked against ~400 CFM per ton. Everything is computed locally and deterministically, so it is instant and private. Ideal for HVAC-design and load-calc tools, mechanical-estimating and commissioning utilities, and building-engineering apps. Pure local computation — no key, no third-party service, instant. Standard-air factors — adjust for altitude. 3 compute endpoints. For room rule-of-thumb sizing use an HVAC API; for moist-air properties a psychrometric API; for duct sizing a ductwork API.
api.oanor.com/hvacload-api
Electric Motor FLA API
Electric-motor electrical maths as an API, computed locally and deterministically — the full-load-current, NEC-sizing and starting-current numbers an electrician, panel designer or estimator runs for every motor circuit. The full-load-amps endpoint gives the motor current from its power, voltage and phase: FLA = (output ÷ efficiency) ÷ (√3 × volts × power factor) for three-phase (drop the √3 for single-phase) — a 10 hp, 460 V, three-phase motor at 90 % efficiency and 0.85 power factor draws about 12.2 A — and it also returns the input kW and kVA. The sizing endpoint applies NEC Article 430 from the full-load current: branch-circuit conductors at 125 %, overload protection at 115–125 % by service factor, and branch-circuit short-circuit/ground-fault protection up to 250 % for an inverse-time breaker or 175 % for a time-delay fuse — the larger protection lets the inrush pass while the overload guards the windings. The starting endpoint gives the locked-rotor (inrush) current, about six times full-load for an across-the-line start, the figure that sets the voltage dip and why soft starters and VFDs exist. Everything is computed locally and deterministically, so it is instant and private. Ideal for electrical-design and estimating tools, panel-builder and field utilities, and engineering calculators. Pure local computation — no key, no third-party service, instant. Calculated values — use the NEC FLC tables for code work. 3 compute endpoints. For general three-phase power use a three-phase API; for conduit fill a conduit API.
api.oanor.com/motorfla-api
Heat Pump COP API
Heat-pump and refrigeration performance maths as an API, computed locally and deterministically — the efficiency numbers an HVAC engineer, energy auditor or heat-pump installer actually works with. The cop endpoint gives the coefficient of performance and the US EER rating from the thermal capacity and the electrical power: a unit moving 7 kW of heat on 2 kW of electricity has a COP of 3.5 (an EER of 12), meaning 3.5 units of heating or cooling for every unit of electricity — which is why a heat pump beats resistance heating, where the COP is exactly 1. The carnot endpoint gives the unbeatable ideal limit set only by the absolute temperatures — heating = Th ÷ (Th − Tc), cooling = Tc ÷ (Th − Tc) in kelvin, where heating COP always equals cooling COP plus one — and, given a real COP, the second-law efficiency that says how close the machine runs to that ceiling; the smaller the temperature lift, the higher the limit, which is why ground-source and low-temperature systems beat air-source on a cold day. The capacity endpoint turns electrical power and a COP into the delivered heating or cooling in kilowatts, BTU per hour and tons of refrigeration — the extra energy over the electricity is pulled from the outside air, ground or water. Everything is computed locally and deterministically, so it is instant and private. Ideal for HVAC and refrigeration engineers, energy auditors, heat-pump and building-performance tools, and sustainability dashboards. Pure local computation — no key, no third-party service, instant. Estimates at the stated conditions — real COP falls as the temperature lift rises. 3 compute endpoints. For room sizing use an HVAC BTU API; for moist-air properties use a psychrometric API.
api.oanor.com/heatpump-api
Steam Boiler API
Steam-boiler engineering maths as an API, computed locally and deterministically — the three numbers a boiler operator, plant engineer or steam-system designer actually works with. The boiler-hp endpoint converts a required heat output into boiler horsepower (heat ÷ 33,475 BTU/hr, the standard definition), the equivalent steam output in pounds per hour "from and at" 212 °F (34.5 lb/hr per BHP) and the output in kilowatts — a 1,000,000 BTU/hr load is about 29.9 BHP or 1,031 lb/hr of steam. The factor-of-evaporation endpoint gives the real capacity for your feedwater: the factor = (the total heat of the steam − the feedwater heat) ÷ 970.3, always greater than one because the boiler must add the sensible heat to bring water up to boiling, so a boiler rated "from and at" 212 °F actually makes less with 60 °F feedwater — which is exactly why preheating feedwater with an economiser raises capacity and saves fuel. The blowdown endpoint gives the continuous blowdown rate to hold the boiler water within its dissolved-solids limit: blowdown = steam × feedwater TDS ÷ (boiler limit − feedwater TDS), with the cycles of concentration and the blowdown as a percentage of feedwater — better feedwater means more cycles, less blowdown and less wasted hot water. Everything is computed locally and deterministically, so it is instant and private. Ideal for boiler operators, steam-plant and HVAC engineers, energy auditors, water-treatment specialists and process-engineering tools. Pure local computation — no key, no third-party service, instant. Engineering estimates — verify against the manufacturer data and local code. 3 compute endpoints. For moist-air properties use a psychrometric API; for compressed air use a compressor API.
api.oanor.com/boiler-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for HVAC BTU Calculator API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call HVAC BTU Calculator API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for HVAC BTU Calculator API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does HVAC BTU Calculator API cost?
HVAC BTU Calculator API has a free tier with 100 calls / month. Paid plans start at €12.75 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is HVAC BTU Calculator API GDPR-compliant?
All requests to HVAC BTU Calculator API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/hvac-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/hvac-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/hvac-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);import requests
r = requests.get(
"https://api.oanor.com/hvac-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
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