Burn time calculator - is this useful for you?

[webbie]

What do you think of this?
https://www.hearth.com/econtent/index.php/articles/burn_time_calculator

I'm trying not to "over feature" it - keeping it simple so it provides a general guide to expectations.

Opinions welcome.

 

[zzr7ky]

I like it! Simple and effective.

Mike P

 

[swestall]

That's pretty neat!

 

[begreen]

Nice idea, I like it! This is really useful and will save a lot of pencil work. Thanks Craig and Bokehman.

It would be nice if there were also a calculator where one could enter the current btus (therms, gals of oil, gas, etc.) the house is consuming, by entering the amount off their monthly oil, gas, electric bill amount. Then derive what size stove it would take to put out the same amount of heat. This seems to be one of the most frequent questions we get here.

Now if we could only get every stove manufacturer to post firebox capacity in their specs.... Jotul are you listening?

 

[webbie]

I think I will be able to get all cubic foot measurements....if not we will measure them ourselves. Then I intend to tie the calculator to a listing of stoves - just click on the stove for the burn times!

 

[karl]

I'm interested in how you determined the difference in heat output between epa stoves and epa inserts. Obiviously, the insert efficiency is less. Did you measure how much less, pick an arbitrary number, or is there some published information about it? Also to save alot of questions later, I would list oak in the wood types.

I do like the calculator alot.

 

[webbie]

All of the numbers leave a lot of slop.....for instance, the actual pounds of wood depends on the shape of the splits and rounds, the length, etc.

So with the inserts and stoves I just used what knowledge is available - about freestanding stoves - and then took a multiplier off of that for inserts. Inserts have:
1. No pipe to radiate
2. An outside shell which loses heat
3. Some heat soaked up by masonry mass (most inserts are in exterior fireplace).

In my opinion, this should reduce the output by about 15% compared to the same stove freestanding with pipe....

A rough guide, of course, but I think still better than nothing.

Yes, I will add some oak species....there is a wide difference between some oaks!

 

[newbie 08]

Could you list for me the different types of woods that would fall into each category on the table?

 

[annette]

I agree, you'd better list oak in there! Maybe other areas have really common woods that should be added, but without making it a really long list. Since a lot of the people using the calculator will be new to shopping for woodstoves, maybe there can be some links to pages that list or explain things in more detail.

I know you capitalized OUTPUT--but I still have to ask: is this the calculated "net" BTUs into the home, or gross, meaning it includes what goes up the chimney? Output could also be into the chimney...I figure if I'm wondering, then others will too.

Is there any way to add a factor for interior vs exterior chimneys? I know that no two houses will be the same, but an exterior chimney really reduces the heating ability of stoves. This is a great tool for people planning their purchase, so if something could be worked in, that would help a lot.

Lastly, aren't there catalytic inserts? You don't have that in the menu.

Overall, a very cool calculator!

edit: while I was typng, you were sort-of answering one question. So an insert is already assumed to be in an outside chimney.

 

[BrotherBart]

And maybe separate BTU numbers for red stoves and black stoves.

 

[webbie]

http://www.engineeringtoolbox.com/wood-combustion-heat-d_372.html

Shows the density of lbs per cubic foot of air dried wood. You can see that the values range from 24 to 51

For purposes of this calculator, I used

Soft = 25;
Medium = 30;
Hard = 38;
ExtraHard = 44;

The calcs are intentionally conservative (real world) and take into account such things as that your firebox is already partially full of ash and embers when you reload, etc. - This is information that manufacturers tend to forget about when listing wood capacities. It is almost impossible to completely fill a firebox perfectly.

 

[BrotherBart]

I think the calculator is great. Thanks for coming up with it. There are always variables that no calculator can address. Like my firebox being 3.5 CF but the instructions say never load it past the top of the firebricks. So usable space, as addressed by the calculator is actually 3.0 CF.

 

[paulie]

Good job web, very interesting...like it. It will be very helpful to many !

 

[RonB]

Looks good. Is there an easily available link to how many BTU's one would need to heat their house? That would go hand in hand with this table.