Watt to BTU/h
How to convert from Watt to BTU/h?. You need to multiply the Watt value by 3.412141633. Here is a calculator that do that for you.
Power in BTU/h:
The Conversion Watt to BTU/h
Basic Formula:
1 Watt=3.4121416331 BTU/h
Thus, to convert:
Power (BTU/h)=Power (Watt) × 3.4121416331
Inversely:
1 BTU/h=0.2930710702 W
These conversion constants are derived from the definitions of the BTU and the Watt, and how they relate to energy per unit time.
Understanding the Units
Watt
- SI unit of power (energy per time).
- Defined as: 1 Watt=1 Joule/second
BTU/h (British Thermal Unit per hour):
- A unit of power commonly used in the US, especially in HVAC, heating, and cooling systems.
- BTU (British Thermal Unit) is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
- 1 BTU ≈ 1055.06 Joules (although slight variations exist depending on definition – more on that in a second).
Curiosity: Multiple Definitions of the BTU
There are several definitions of the BTU, depending on the temperature at which the heat transfer is measured:
- BTU(IT): International Table – the most commonly used value: 1055.05585 J
- BTU(ISO): ≈ 1055.056 J
- BTU(Mean): ≈ 1055.87 J
- BTU(39°F), BTU(60°F), etc.: defined based on the heat capacity of water at specific temperatures
For most engineering and HVAC calculations, BTU(IT) is used, and that’s where the 3.4121416331 factor comes from.
Where It’s Commonly Used
- HVAC Design: Cooling/heating systems are almost always rated in BTU/h in the US. For example, an air conditioner might be 12,000 BTU/h (equivalent to ~3.5 kW).
- Appliance Ratings: Gas furnaces, water heaters, and stoves may be rated in BTU/h, especially in North America.
- Energy Efficiency Metrics: Such as SEER (Seasonal Energy Efficiency Ratio), which relates BTU/h to power input in watts.
Example Conversions:
1. Convert 1500 W to BTU/h:
1500 × 3.4121416331 = 5118.21 BTU/h
2. Convert 12000 BTU/h (typical small AC unit) to Watts:
12000 × 0.2930710702 ≈ 3516.85 W
F.A.Q.
Why BTU/h Instead of Just BTU?
People often (erroneously) say “BTU” when they mean “BTU/h”. But a BTU is a unit of energy, not power. Only BTU per hour is a rate of energy transfer, i.e., power.
What is a Ton of Refrigeration
1 ton of cooling = 12,000 BTU/h. Based on the amount of heat absorbed when melting one ton (2000 lbs) of ice over 24 hours. Therefore: 1 ton=3.51685 kWatt
Why Watts Are Standard in Europe, but Not the U.S.?
The U.S. still uses Imperial units in building services (e.g., BTU/h, tons, °F, inches). The rest of the world, especially under ISO and IEC standards, uses Watts, kW, and Joules.
🧰 Summary Table
| Unit | Symbol | Equivalent |
|---|---|---|
| 1 W | W | 3.4121416331 BTU/h |
| 1 BTU/h | BTU/h | 0.2930710702 W |
| 1 ton (cooling) | – | 12,000 BTU/h ≈ 3.51685 kW |
| 1 BTU (IT) | – | 1055.05585 J |
