Just for kicks..........

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heaterman

Minister of Fire
Hearth Supporter
Oct 16, 2007
3,374
Falmouth, Michigan
I got thinking about heat loss of an OWB sitting out in the yard and ran a rough calculation on my heat loss software. If the jpeg screen shot attaches here you'll be able to see the calcs for each surface of the OWB. I figured the unit to be 4 feet wide and 6 feet long with a side height of 6" and the ends at 7'. I used R19 in the side walls and R-11 on the ends with a 3'x4' door also at R-11. The top was R-28. I think this pretty much reflects the insulation on a run of the mill OWB. I calculated the heat loss at -6* outside and 180* (that would be the water temperature) inside the structure. I used a poor air change per hour figure that is in reality probably pretty generous.

So just for giggles let's knock it down to 5,000 for easy figuring and also to reflect the fact that the whole winter is not -6* and see how much wood that adds up to over a heating season.

5,000 x 24 hours in a day = 120,000 btu/day. If our heating season is roughly 200 days like here, that's 24,000,000 btu's lost. Factor in an efficiency of 50% (again generous) and you are looking at 48,000,000 btu's worth of heat. That's the equivalent of about 2-1/2 full size cords of wood.

I kinda enjoy helping the boys do their wood (all 4 of em burn) but cutting hauling splitting stacking and then loading that much extra wood every year.............just sayin' ........

Consider all the factors before you make a decision.
 

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YOWZA!!

Add to that a bunch more Btu's lost to some crappy underground lines and you'd have a fine example of a TOTAL waste time and money. Even if you figured the "efficiency" of these things at say 80%(very generous) you would still have a scary number.

Standby heat loss should really be a big part of any efficiency claim.

Thanks for posting,
Noah
 
ken999 said:
Whattaya talkin' about???...there's OWB's out there that are 99% efficient.....???.....

maybe if they were struck by lightning :)
 
By the time we get our lightning ro....er ah...taller smoke stacks installed per the new reg's, we WILL be turning the meters backwards...lol...

Why you always gotta pick on the 50% efficient crowd anyways?
 
ken999 said:
By the time we get our lightning ro....er ah...taller smoke stacks installed per the new reg's, we WILL be turning the meters backwards...lol...

Why you always gotta pick on the 50% efficient crowd anyways?

Cause I hesitate to kick a guy when he's really down.............like all the poor beggars out there with units running 30-35% ;)
 
True Dat!

Just for giggles...how much loss would you expect from the 2300 sitting all day w/ no circ.??

450 gallons @190??..

What would be acceptable for you?
 
heaterman said:
ken999 said:
By the time we get our lightning ro....er ah...taller smoke stacks installed per the new reg's, we WILL be turning the meters backwards...lol...

Why you always gotta pick on the 50% efficient crowd anyways?

Cause I hesitate to kick a guy when he's really down.............like all the poor beggars out there with units running 30-35% ;)


LOL: you mean like me burning my 20-25 cords/tear :sick:
 
ken999 said:
True Dat!

Just for giggles...how much loss would you expect from the 2300 sitting all day w/ no circ.??

450 gallons @190??..

What would be acceptable for you?

If the surface areas are roughly the same, it would probably be pretty close to what i have listed above. I haven't had the opportunity to "sniff" a 23 or 2400 yet so I don't know what the efficiency is. I'm gonna say 60% would be very optimistic based on the difference between CB's past claims for older units vs real world numbers that were generated in an independent lab test and my own.
 
phew...

I'm looking at roughly 10 chord from Oct. through May.

Probably 1/2 chord per month for domestic only (summer use) June-Sep.

I'm not real sure yet on the summer numbers as I'm just getting into the swing of things with my boiler and I'm trying to guage things based on what I'm currently burning...trouble is we are still taking heat off the boiler 2x a day for the house in general as it's been chilly overnight.

All in all I'd expect around 12 chord total for the year. When we finally get the house insulated properly, that number should drop significantly. Even so...we've got 21 acres of wood, so it's pretty cheap.
 
I'm getting around 2-3 degrees loss all day long while we are at work.

I didn't think it was too bad....

You gotta remember though...there is no idle time for me in this weather. I light it and it burns wide open until I shut it off.

From what I hear about the spray foam like I have on the 2300 , there is a point of diminishing returns after 2-3 inches? no?...

Anytime you deal with storage, it's an automatic loss. People who have large storage are trading pure efficiency for ease of use (I certainly don't blame them...)(course the flip side is bigger deltas = higher efficiency...)

So I guess in defense of my 60% efficient boiler, I'm only fireing during times of peak use, minimizing my losses due to storage in-efficiency.
 
About 6 inches where we are, YMMV. R50 or a bit more.

Storage has other benefits, but there is no reason why the heat loss should be that significant. If it is the building then there is effectively none.
 
Right. I shouldn't have worded it "Anytime you deal with storage..." Those who have room for storage in their home are not losing anything. I'm thinking more about those situations where in-house storage is not an option. Modular homes and trailers on slabs etc. It's tough to put storage in a basement if you don't have one or it's an old style farmhouse with a stone foundation. Alot of times there just isn't room.

I'll have to try letting my 2300 sit for a day (12 hrs) during winter conditions to see what it will do at zero. Last night, I left the circ on and it dropped 35 degrees overnight. My pex isn't insulated in the basement though so thats expected. Since it was 32 this AM, a little bleed off into the house was a good thing.
 
ken999 said:
Whattaya talkin' about???...there's OWB's out there that are 99% efficient.....???.....

The stove that you are talking about has sand in the bottom of it. Unlike all others that has metal and refectory cement. The sand bottom holds moisture from the burn thus weighing more than it did at start of test. I know how stupid !!! This give it a higher efficiency rating. They (EPA)know thats the problem but have not came up with a way to solve it. This stove highlights Heatermans point on heat loss sitting outdoors. It has no insulation on front , back or bottom. In my opinion for what it is worth. This furnace is the poorest insulated furnace out there.


The problem with common scene is it is not so common........ Mark Twain
 
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