Btu

[zmedic]

Ok. So pardon my ignorance. My question is how is it that a stove with an out put of 48,200 (model 6039) does less sq ft than a stove with a max output of 48,000 (5500m)? I keep hearing btu is king as well as airflow etc. i have asked a bunch of people with no answers.
thanks

 

[Phoenix Hatchling]

I would imagine the ability of the two units to radiate and dissipate the heat it gives off. If you have a bigger hotter unit which doesn't release that heat as readily, whether through direct radiation and surface area or convective blowers, then the smaller unit which puts out less BTUs but puts it out efficiently wins.

 

[Harvey Schneider]

First, the BTU specs are almost always input specs. The stove's efficiency reduces the available BTU's for output. So a lower efficiency stove with higher input capacity may have less heat output.
Second, the square foot heating capability is an estimate, not a fact. The actual capacity in sq ft is influenced by climate, construction. insulation, windows and prevailing winds just for starters.
The most accurate guide is the BTU input spec multiplied by the efficiency. That will tell you the actual amount of heat the stove is capable of delivering to your home.

 

[skibladerj]

A manufacturers claims of how much sq. Ft. A stovr can heat is only a suggestion. I have seen stoves (coal) rated for 1000sq to 5500sq. Thats a big swing. Ever home has a heat loss factor that dictates how many btu's is needed to heat that space.

Airflow has more to do with the thermal currents and covection loop within your home and/or room.

 

[zmedic]

I do have a very drafty house, built in the 1890's. I am in Northern NY so very cold. I have thought maybe the harman will be the only way. My American Harvest 6039 does an ok job. I thought the 5500M maybe my better bet but the input is 52,300 and output is 48,280 where as the 5500M is 48,000 95%. But maybe as said above is just more efficient at getting it out. Not sure on the efficiency of the 6039. I can pick up the 5500M for $450.00 and sell the 6039 is my thought or just install both ! Let me know your guys' thoughts

 

[Harvey Schneider]

5500M is 48,000 95%

95% is hard to believe. Typical numbers run from mid 70's to mid 80's.

 

[skibladerj]

You could do both but im running around 3lb/hr on my 5500m(on a t-stat) whivh comrs out at almost 2bags a day. I dont think USSC has the best heat exchange idea.

 

[john193]

95% of stats are made up...

 

[zmedic]

I agree it does seem high. It was just an idea. But for the price I can get it and the piping I could resell or something. Try the 5500M and see what happens I guess. I agree their exchangers aren't the greatest. If only I could make it better! Hopefully next winter finances will allow a harman or something a step or up. Maybe the Timber ridge 55-TRPIP who knows

 

[Bioburner]

Keep and eye out for nice used stoves. People start moving again in the spring and seems to be one thing that does not go with home sales so on to Craigslist etc. With this cold spell and shortage of propain the supply of good stoves on CL have vaporized and local box stores don't have anything in our area.

 

[stoveguy2esw]

BTU "British Thermal Unit" the amount of energy to raise the temperature of 1 gallon of water 1 degree F.

one lb of wood (virtually any wood) by weight not volume contains roughly 8500BTU.

a pellet stove simply releases the thermal energy of the wood it consumes. of this energy a portion leaves through the exhaust, the rest is either transferred into the convective airstream or absorbed into the body of the stove and released as radiant heat.

most pellet stoves will release about 80% of this heat into the space being heated either through convection or radiance. the rest goes "out the pipe"

so a stove capable of "40KBTU" per hour , would have to burn just under 5 lbs per hour to "release" this energy through combustion, from the fuel.

in order to "output" this much energy the stove would have to release a much higher amount of energy.
lets do some math, a stove burning 1 lb of fuel per hour at say 78% efficient (default for certification) if it transfers 78% of that energy to te room the BTU "output" would be 6630 of the 8500 with 1870BTU out the pipe. so a stove burning 5 lbs/hr based on this would only output 33,150BTU/HR

using the op's number of 48000BTU "output" the stove would require 7.239 lbs/hr consumed to push that much heat into the room. the 95% claim in my mind is not feasible but even still it would require 6 LBS/HR @ 8075BTU?LB (output) to create that amount of heat output at 95% thermal efficiency.

math bears this out. here's the thing folks and I'll be as plain as I can be;

stoves don't heat, the release of thermal energy released by the consumption of fuel does. regardless of the stove (or if you dump the pellets on the floor and light them like a campfire, they only contain a finite amount of heat. some stoves may have a higher absorption rate and thus a higher thermal transfer rate than others , but the cold hard facts are that most stoves claim certain BTU ratings , this is running wide open with consumption rates similar to what I posted above, and very few folks will run at that rate as it would not be cost effective. so a "60KBTU" stove will not produce any more heat than a "40KBTU" stove when they both burn the same amount of fuel per hour. they may "transfer" a bit higher percentage, but not 20KBTU/HR from the same fuel amount.

 

[stoveguy2esw]

I agree it does seem high. It was just an idea. But for the price I can get it and the piping I could resell or something. Try the 5500M and see what happens I guess. I agree their exchangers aren't the greatest. If only I could make it better! Hopefully next winter finances will allow a harman or something a step or up. Maybe the Timber ridge 55-TRPIP who knows

I just reworked 3 of them last weekend for andy at amfm. its a nice unit.

 

[stoveguy2esw]

I do have a very drafty house, built in the 1890's. I am in Northern NY so very cold. I have thought maybe the harman will be the only way. My American Harvest 6039 does an ok job. I thought the 5500M maybe my better bet but the input is 52,300 and output is 48,280 where as the 5500M is 48,000 95%. But maybe as said above is just more efficient at getting it out. Not sure on the efficiency of the 6039. I can pick up the 5500M for $450.00 and sell the 6039 is my thought or just install both ! Let me know your guys' thoughts

ok Z,

here's the question; how much fuel do you burn in a 24 hour period? are you running the stove maxed out?

a wise person above posted about heat loss, in an old house this is important as they weren't exactly built "tight" and only extensive renovations will change this.

remember a pellet stove (or wood stove) is a 'space heater" just like the cheap Charlie electric thingys you buy at wally world for 20 bucks and plug in so you can watch your meter look like a CD player.

heat is not destroyed (physics) its only dissipated. essentially the heat generated and transferred is carried by molecules which absorb energy and carry it with them (the "colder" the molecule the less energy it possesses and the more it "craves it" when exposed to a molecule which has more energy (remember nature abhors a vacuum) so a particle which is charged with "X" amount of energy when it encounters a particle which has less will be "robbed' of part of that energy as they pass in proximity until each particle has the same amount (call it "physical socialism" he (particle) who has , gives until all have equal) this is dissipation. the lesser ability to "hold heat" in older houses allows more "cold particles' in and means more energy has to be released constantly to achieve "physical equality"

its complicated in description, but easy to understand when viewed in a less scientific manner think about it this way, say a country has a law where everyone is entitled to the exact same amount of a commodity (heat in his case) when more people come in the "heat is more thinly distributed" (and no im not making a political statement this is strictly an exercise in physics laid out in a different manner) so say yoyu have 100 units of heat and you have 50 "particles" to share it, now in a leaky house say 50 more enter, you then divide the equal share as half of what each had before the others came in, so you have half as much energy per unit of measure ad thus you need to make twice as much energy to bring the level back up to the "pre invasion" level.

I hope this makes sense to all, and like I said , I wasn't making this intro a political discussion , merely using this model to lay out a "laymans terms" description on how heat dissipation works

 

[nailed_nailer]

95% of stats are made up...

Todd Snider's Statistician's Blues

> > >Caution< < < Few Curse words in this

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---Nailer---

 

[Harvey Schneider]

Todd Snider's Statistician's Blues

> > >Caution< < < Few Curse words in this

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---Nailer---

What I learned in college;
There are lies, there are damned lies, and then there are statistics....

 

[john193]

Todd Snider's Statistician's Blues

> > >Caution< < < Few Curse words in this

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---Nailer---

Ahh yes, very nice. I see your Todd Snider and raise you an anchorman. This part always gets me.

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[zmedic]

I burn 2 bags a day and not a fully wide open but I modulate back and forth as I do have a newborn at home. If I go wide open all day about 2 1/4 bags and if its below 30 will keep the 600 sq ft at 70 and upstairs at around 50. I usually back the upstairs up with a space heater.

 

[stoveguy2esw]

thats a lot of fuel for that amount of space. i noticed the house is described as drafty, are you able to do some "temporary" things to help cut down on the heat loss?

start thinking about insulation as well, i will tell you from experience , there is no greater ROI than insualtion especially if you own the house , you can claim some of the cost against taxes as well.

 

[zmedic]

I have started filling in some of the cracks and it has improved it but it is plaster and lathe walls so need I say more LOL