# How does the EPA measure BTU's?

Posted By Machria, Nov 18, 2012 at 8:21 PM

1. #1

### Machria Minister of Fire 2. ```NULL ```

Nov 6, 2012
1,117
389
Loc:
Brookhaven, Long Island
Hey guys,
How does the EPA (or whoever does it?) measure the BTU's? I know they use special wood with 1" gaps.... but, then how do they measure the BTU's? Do they somehow measure the heat in a special sized room, or ....???

2. #2

### HotCoals Minister of Fire 2. ```NULL ```

Oct 27, 2010
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Good question,wiki goes on forever aboit any question ..but here is part of it.

A Btu is defined as amount of heat required to raise the temperature of one 1 pound (0.454 kg) of liquid water by 1 °F (0.556 °C) at a constant pressure of one atmosphere. As is the case with the calorie, several different definitions of the Btu exist, which are based on different water temperatures and therefore vary by up to 0.5%: A Btu can be approximated as the heat produced by burning a single wooden match[2] or as the amount of energy it would take to lift a one-pound weight to a height of 778 feet (237 m).[3]

3. #3

### Machria Minister of Fire 2. ```NULL ```

Nov 6, 2012
1,117
389
Loc:
Brookhaven, Long Island
Nobody knows hwo they do this? I'm trying to figure out how they figure out how many BTU's a sove puts out?

4. #4

### begreen Mooderator 2. ```NULL ``` Staff Member

Nov 18, 2005
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Loc:
South Puget Sound, WA
5. #5

### Machria Minister of Fire 2. ```NULL ```

Nov 6, 2012
1,117
389
Loc:
Brookhaven, Long Island
That does not show/tell us how they test the BTU's. I understand what a BTU is, the fact the max BTU's is much different than the EPA's listed BTU's, and that the EPA uses test soft wood to do the test.

But what the question is, what are they measuring to come up with the BTU number? Are they mesureing the temperature of something(the room, the stove, the exaust..)? Are they just measureing how fast it burns the wood which is a preset # of BTU's? Example, they start with 20,000 btu's worth of wood, burn it, and see how long it took. If it takes one hour, then it is a 20,000 BTU/hr unit. If it burns it in 1/2 hour, it is a 40,000 btu/hr unit...

So how do they measure the BTU's?

6. #6

### Machria Minister of Fire 2. ```NULL ```

Nov 6, 2012
1,117
389
Loc:
Brookhaven, Long Island
Ok, found some more on that link that shows the calculation they use... hmmm.... interesting stuff..

begreen,
Did you ever notice in your Avatar picture, there is a guy figure on the right side in the flames, from shoulders up, and he is at about a 45 degree angle facing to the left. And on the left, there is a woman facing the man (we are looking at her side profile from chest up), her hair is in a pony tail, and she is topless. The rising fireball in the middle looks like an alien!!

jeff_t likes this.
7. #7

### ddddddden Minister of Fire 2. ```NULL ```

Oct 20, 2009
1,335
162
Loc:
Central Va
I see it!
BG has been subliminally conditioning us to like hearth.com more than porn!

p.s. That avatar used to be a nice animated gif. . .dunno whether the new xenforo doesn't support it, or my new web device doesn't.

8. #8

### begreen Mooderator 2. ```NULL ``` Staff Member

Nov 18, 2005
63,850
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Loc:
South Puget Sound, WA
Busted! lol

It's animated but so far xenforo does not support animated gifs for avatars. It previews correctly in my profile settings, but not in the forum.

9. #9

### Machria Minister of Fire 2. ```NULL ```

Nov 6, 2012
1,117
389
Loc:
Brookhaven, Long Island
LOL!! Had you ever noticed that before?

I did see it was animated when I clicked on it.. But I like the freeze frame better!

10. #10

### Woody Stover Minister of Fire 2. ```NULL ```

Dec 25, 2010
8,014
2,263
Loc:
Southern IN
Who could blame her? It's mighty hot in there!
I assume you've been looking at the EPA BTU output ratings. If so, take these with a grain of salt. I've found several rating that seem not to be in line with prevailing wisdom here. I would dig up some examples but I'm kinda busy right now...
But I 'm sure they have sophisticated test equipment that they use to come up with the ratings. Not sure why their results wouldn't reflect real life but apparently that's the case.

11. #11

### BrowningBAR Minister of Fire 2. ```NULL ```

Jul 22, 2008
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Doylestown, PA
Based on the wild differences of BTU output from stove manufacturer to stove manufacturer, I always assumed it involved randomly picking out overly optimistic numbers blindly from a hat.

12. #12

### Machria Minister of Fire 2. ```NULL ```

Nov 6, 2012
1,117
389
Loc:
Brookhaven, Long Island
LOL!!

Actually, I have not been focusing on any particular rating per say, but I was focusing on the relationship between the BTU ratings and the claimed square footage to be heated. It's too bad there is not a better more acurate measurement of how much heat one will get from a stove. It makes it very difficult to choose the correct sized stove for a given space. I found a calculator on Woodstocks site that lets you put in the size of your room, then select ceiling height, then the basic insulation (Poor, ok, Good, extremely good), and it tells you the estimated BTU's you require. So that is what got me thinking about this.... I also watched the Woodstock video of them testing the low burn emmisions of the Progress hybrid with cord wood. So it's easy to see how they measure emmisions, they measure what particles are going out the stack. But, what do you measure for BTU's?

What is needed is a set space (say 1000 sq feet) at a set temperature and atmosphere (temp, humidity, pressure...). Then set each stove in the room and burn preset amounts of EPA style wood based on the firebox size. Then graph the rooms temp. rise and fall over the time of the burn. Then pick a temp, say 70 degrees and rate each stove for how long it can hold that "test" room environment at that temperature or above. And or just average the temp the stove kept the room over it's burn time. So you would end up with something like:

Rating method one (how long did the stove hold the setpoint temp):
Stove 1 rating: 3 hours
Stove 2 rating: 9 hours
Stove 3 rating: 4 hours

Rating method two (Average room temp / hours of burn time) = what it tells us about the stove:
Stove 1 rating: 75/2 (brought room to an avg of 75 degree's for 2 hours) = Avg heat, with short burn time
Stove 2 rating: 74/8 (brought room to an avg of 74 degree's for 8 hours) = Avg heat., long burn time
Stove 3 rating: 95/3 (brought room to an avg of 95 degree's for 3 hours) = hot stove, but short burn time

And we would get each stoves graph, so we can see how linear or non-linear the heat curve is with each stove.

13. #13

### Woody Stover Minister of Fire 2. ```NULL ```

Dec 25, 2010
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2,263
Loc:
Southern IN
That would be great but until the rocket scientists get involved, we're left with the maxim that's often repeated here with regard to stove selection; Better a little too big than too little.
And about the "alien" in begreen's stove...how many aliens have you seen and could you please describe them in detail?

14. #14

### Machria Minister of Fire 2. ```NULL ```

Nov 6, 2012
1,117
389
Loc:
Brookhaven, Long Island
I'm more focused on the topless young lady than the alien!!

But if you really want to know, I have not seen any aliens, YET. But I have seen several UFO's (all in the same sighting)!

15. #15

### Woody Stover Minister of Fire 2. ```NULL ```

Dec 25, 2010
8,014
2,263
Loc:
Southern IN
One of my neighbors had a helluva sighting...