BTU/hour to BTU/second
BTU/h
BTU/s
Conversion History
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Quick Reference Table (BTU/hour to BTU/second)
| BTU/hour (BTU/h) | BTU/second (BTU/s) |
|---|---|
| 5,000 | 1.38888888888888994202 |
| 8,000 | 2.22222222222222390723 |
| 12,000 | 3.33333333333333586085 |
| 18,000 | 5.00000000000000379127 |
| 36,000 | 10.00000000000000758254 |
| 60,000 | 16.66666666666667930423 |
| 100,000 | 27.77777777777779884038 |
About BTU/hour (BTU/h)
BTU per hour (BTU/h) is the standard power unit for heating and cooling equipment in the United States — air conditioners, furnaces, heat pumps, and water heaters are all rated in BTU/hour. One BTU/h equals approximately 0.293 watts. A typical window air conditioner is rated at 5,000–24,000 BTU/h; a central HVAC system for a mid-sized home at 36,000–60,000 BTU/h (called "3 to 5 tons"). The unit appears exclusively in US thermal and HVAC engineering.
A 12,000 BTU/h (1-ton) air conditioner uses roughly 1,200 W of electricity while removing 3,517 W of heat from the room. A typical US gas furnace is rated 60,000–100,000 BTU/h.
About BTU/second (BTU/s)
BTU per second (BTU/s) is a high-power thermal unit equal to approximately 1,055 watts. It is used in large-scale industrial heating, combustion engineering, and power plant heat rate analysis where BTU is the preferred energy unit and the timescale is seconds. One BTU/s is roughly the power of a small domestic gas boiler running continuously. The unit bridges the BTU-based thermal engineering tradition with second-based rate measurement.
A large industrial gas burner rated at 5 BTU/s delivers about 5,275 W of thermal power. A 1 BTU/s heat source could raise 1 lb of water by 1 °F every second.
BTU/hour – Frequently Asked Questions
How many BTU/h air conditioner do I need for my room?
The classic rule: 20 BTU/h per square foot. A 300 sq ft bedroom needs about 6,000 BTU/h; a 500 sq ft living room about 10,000 BTU/h. But this varies wildly with sun exposure (+10% for south-facing), ceiling height, insulation quality, number of occupants (+600 BTU per person), and climate zone. A room above a pizza oven in Phoenix needs more than a basement in Seattle. When in doubt, oversize slightly — an undersized unit runs constantly and never reaches setpoint.
What happens if you oversize or undersize your home AC unit by a ton?
Undersizing is obvious — the unit runs constantly and never reaches the thermostat setpoint on hot days. But oversizing is worse in subtle ways. An oversized AC cools the air quickly then shuts off before removing enough humidity, leaving you with a clammy 72°F house. The short cycles also wear the compressor faster (startup is the hardest moment) and waste energy. A 1-ton oversize in a humid climate like Florida can raise indoor humidity from a comfortable 45% to a muggy 60%. Proper Manual J load calculations matter more than most homeowners realize.
What does "1 ton" of air conditioning mean in BTU/h?
Exactly 12,000 BTU/h. One ton of AC is the cooling effect of melting one short ton (2,000 lbs) of ice over 24 hours. The ice absorbs 288,000 BTU of heat as it melts (2,000 lbs × 144 BTU/lb latent heat), divided by 24 hours = 12,000 BTU/h. Residential systems run 1.5–5 tons; commercial buildings 10–500 tons. The "ton" unit persists because HVAC contractors think in tons — "that house needs a 3-ton unit" is faster than "that house needs 10.5 kW of cooling."
How efficient is a modern air conditioner in BTU/h per watt?
Modern units achieve 12–25 BTU/h per watt of electricity (SEER 12–25). A SEER 20 unit removes 20 BTU/h of heat for every watt consumed — effectively a 3:1 heat pump ratio. That 12,000 BTU/h window unit draws 500–1,000 W of electricity depending on efficiency. The best mini-splits achieve SEER 30+, removing 30 BTU/h per watt, making them cheaper to run than resistive electric heaters even in heating mode.
How do BTU/h ratings differ between gas furnaces and heat pumps?
A gas furnace's BTU/h rating is its thermal output after combustion efficiency losses (typically 80–96% of fuel input). A heat pump's BTU/h rating is the heat delivered including energy moved from outside — at COP 3, a heat pump delivering 36,000 BTU/h uses only 12,000 BTU/h worth of electricity. This makes direct BTU/h comparisons misleading: a 60,000 BTU/h furnace and a 60,000 BTU/h heat pump deliver the same heat, but the heat pump uses one-third the energy.
BTU/second – Frequently Asked Questions
Why would anyone use BTU per second instead of kilowatts?
In US combustion engineering and power plant heat rate analysis, fuel energy content is natively specified in BTU (natural gas is sold per therm = 100,000 BTU). Expressing burner output in BTU/s keeps the calculation in one unit system, avoiding constant conversions. When your fuel flow is in BTU/min and your efficiency calculations use BTU, switching to watts mid-calculation just creates errors.
How does 1 BTU/s compare to everyday power levels?
One BTU/s ≈ 1,055 watts — roughly a single-bar electric fire or a small hair dryer. It's a surprisingly human-scale unit. A typical US home gas furnace running at full blast produces about 28 BTU/s (100,000 BTU/h ÷ 3,600). A gas stovetop burner on high delivers about 3–5 BTU/s. So BTU/s lands right in the range where you can feel the heat on your face.
What industries commonly use BTU per second?
Power plant thermal engineering (heat rate analysis), industrial furnace and kiln design, jet engine combustion analysis, and rocket propulsion engineering. NASA specifications for rocket engines often include BTU/s figures. The Space Shuttle Main Engine produced about 12 million BTU/s of thermal power. Steelmaking blast furnaces operate at 50,000–200,000 BTU/s of heat input.
How do you convert BTU/s to horsepower?
One BTU/s = 1.415 mechanical horsepower, or roughly 1.4 hp. This is useful in automotive and engine testing where dynamometers may report in BTU/s for thermal measurements but engineers think in horsepower. A 400 hp engine rejects about 280 BTU/s through its cooling system at full power (assuming 60% of fuel energy becomes waste heat). The conversion factor is easy to remember: multiply BTU/s by 1.4 to get hp.
What is a BTU anyway and why does America still use it?
A BTU (British Thermal Unit) is the energy needed to raise 1 pound of water by 1°F — about 1,055 joules. Despite the name, Britain abandoned it decades ago. America keeps it because the entire HVAC, natural gas, and building industry infrastructure — codes, equipment ratings, contractor training — is built around BTU. Switching would require rewriting thousands of standards and retraining millions of technicians. It's inertia, pure and simple.