# Thread: Value of the Watt / Watt Hour from BTUs - Please Verify

1. I searched the internet for the last 2 hours learning and understanding the Watt/Watt Hour/BTU conversions using data collected.

I am not sure what I might be missing, but Wikipedia has supported that a defined Watt ~ 3.412 BTUs.

Some simple constants:

1 Watt (W) = 1 Joule per second
1 BTU ~ 1055.05585 J
1 hour (h) = 3600 seconds (s)

So, inherently, a simple formula can be derived to convert BTUs into what I believe should be Watts:

W = Joules(BTU)/Seconds(Time Elapsed) OR 1055.05585/3600 ~ .293 W Rating

Their number of 3.412 has apparently been used by applying:

W = Seconds/Joules OR 3600/1055.05585 ~ 3.412 W

This makes no sense to me and appears to be the inverse of a Watt.

Once the Watt has been calculated, you simply multiply by the time of usage:

Watts * Time (in hours)

2.

3. That formulas make no sense. You are trying to convert watts to watts?

I am not sure what I might be missing, but Wikipedia has supported that a defined Watt ~ 3.412 BTUs.
This makes no sense. Watts can't equal BTUs, as watt is a unit of power and BTU is a unit of energy.

4. Originally Posted by Twit of wit
That formulas make no sense. You are trying to convert watts to watts?
I am trying to get a general power rating based on energy usage and time elapsed.

If W = J/s, then 1000 BTUs used over 5 hours would give

(1000 BTUs * 1055 J)/(5 hours * 60 *60) ~58.6 J/s OR 58.6 W

5. It seems correct. But what is your point then? Wikipedia says
1000 BTU/h is approximately 293.071 W
293.071/5=58.6142W

6. Simply to calculate the Wattage rating/average of a device from usage and time elapsed. Similar to determining a lightbulbs wattage rating based on its usage

7. Before you edited your post you said that there is something incorrect in wikipedia article about BTU.

8. Originally Posted by WD
Simply to calculate the Wattage rating/average of a device from usage and time elapsed. Similar to determining a lightbulbs wattage rating based on its usage
Why do you need such an obscure unit to calculate the wattage of a device?

9. Originally Posted by Twit of wit
Originally Posted by WD
Simply to calculate the Wattage rating/average of a device from usage and time elapsed. Similar to determining a lightbulbs wattage rating based on its usage
Why do you need such an obscure unit to calculate the wattage of a device?
Apparently that is how international agencies calculate energy usage

10. Originally Posted by Twit of wit
Before you edited your post you said that there is something incorrect in wikipedia article about BTU.
Yes, the claim that 1W = 3.412 BTUs - I was incorrect and was mixing up BTU and BTU/h

11. Originally Posted by Twit of wit
Why do you need such an obscure unit to calculate the wattage of a device?
It is not obscure in the US where BTU is often used as a measure of the heating value of fuels, or the output of an air conditioner, while watt-hours are used to measure electrical energy.

12. 1 joule = 1 watt
1 BTU = 1054 J

1 BTU = 1054 watt if consumed over a time period of 1 second
1 BTU = 0.2929 watt if consumed over a time period of 1 hour

1 watt consumed in 1 second = 0.0009485 BTU

therefore

you can use 0.0009485 BTU * (time in seconds/3600) = BTU/time in hours

1 watt consumed for 1 hour , 3600 seconds = 0.0009485 BTU * 3600 seconds = 3.4146 BTU/hour

if your heater is rated at 10,000 BTU in 1 hour it will probably consume

10,000 BTU / 3.4146 BTU/hour = 2928.600 watts per hour or 2.928 kW/h

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