BTU Question

Mikeylove

I have read several of Dan's books as well as other literature and I was hoping to clarify something; the definition of <strong><span style="text-decoration:underline;">BTU</span>. </strong>Most of the definitions reference a BTU being the amount of heat necessary to raise 1 pound of water by 1 degree Fahrenheit. I understand this but others reference a time, that being one minute; "the amount of heat necessary to raise 1 pound of water by 1 degree in 1 minute".  Which is the correct answer? Thanks in advance for your help. 

Paul Fredricks_3

I don't think

there is a time associated with BTU's. When a piece of equipment has a BTU rating, "per hour" is implied.

DanHolohan

British Thermal Unit

It's the amount of heat needed to raise one pound of water one degree Fahrenheit. Btu has nothing to do with time. There's another term, Btuh, which is Btus per hour and that combines the heat input with time. 

MikeyB

BTU

I read in the Operators Engineer's Exam (posted in teh library) that a BTU "is that heat required to raise water at 39 degrees F. one degree per minute"

Jamie Hall

Dan's right,

the OE exam wrong.  BTU is a measure of energy, and has nothing to do with time.  As soon as time gets into the act, you're talking power, not energy.

Mark Eatherton

I've seen it stated...

that it is roughly the equivalent of a wooden kitchen stick match....



Don't think you could keep a stick match burning for a minute.





Also remember something about two Englishmen drinking at a pub, and determining that it was the amount of energy necessary to raise one PINT of beer, one degree fahrenheit. Or SOMETHING to that effect.



Maybe they were playing with matches :-)



Maybe it should be called an ITU (Irish Thermal Unit) ??



ME

Mikeylove

That BTU thing again

I really appreciate everyone's help and quick responses and I believe I am closer to fully understanding the concept. I have one last thing to add, I was recently watching a video on Taco's site, it was a video by John Barba called "Universal Hydronics Formula" and he stated several times BTU per minute. How does that correlate to our discussion? Thanks again guys.

DanHolohan

Here's the source:

http://www.heatinghelp.com/article/180/Very-Old-Stuff/921/The-Origin-of-the-British-Thermal-Unit



Note how the first Btu was the amount of heat needed to raise one cubic foot of water one degree Fahrenheit.  Mr. Tredgold made it up. We got to change it once he was dead.



May you can make this stuff up!

Mikeylove

Thank you

Thank you very much