I've been burning wrong all along....?

[fattyfat1]

this stove is awesome. I rarely use my blower unless the house is super cold. If you set her on "medium" heat, she chugs up to temp FAST, then dampers herself down and just cooks along. can you say only six splits in 24 hours? the stove is truly a set it and forget it. even on high, I think it could be difficult to overfire, Right now I have her loaded to the top with maple, blower on, (its cold and snowing today) and she took off like a rocket this morning, then auto-dampered down and chugged along. two hours later, she is still plugged with wood, minimal flame, stoves at 550 on top, still on high.

 

[WarmGuy]

For me, the fan doesn't seem to make that much difference, but I usually run it on low, just in case. It's so hard to tell for sure, since there are so many variables (exact amount/quality of wood, moisture content, outside temperature, etc.).

When the power's out (and no blower), the fireplace doesn't heat the house as well.

My blower draws 20 watts on low and 40 on high.

 

[bokehman]

no matter how fast you remove heat from a fire it will not affect the burn time.

Of course it will. A load of wood only has a certain number of BTU's. To extract those BTU's faster you need to burn hotter which lowers your burn duration. If you try to extract them faster than the fire is producing them the fire will go cold/out.

 

[Rockey]

no matter how fast you remove heat from a fire it will not affect the burn time.

. To extract those BTU's faster you need to burn hotter which lowers your burn duration. If you try to extract them faster than the fire is producing them the fire will go cold/out.

I'm not positive but it seems that your putting the cart in front of the horse. Maybe I could understand it if you can explain how a hotter fire lowers the burn duration.

 

[Rockey]

Ok, I see what your saying about removing BTU's faster than a fire can produce it would make the fire go out. Realistically I don't think you can find a stove that can do that. The point was that a stove with the blower on probabaly wont affect the burntime.

 

[North of 60]

That's weird. The blower shouldn't affect your burn time. I think we're not seeing the whole picture.

It does on our stove because the air control runs on a thermostat. when on high, the stove gets up to about 550-650 on top, and automaticaly dampers down to keep stove temps in desired range. cooler stove(ie; blower running) means more air is open and wood will burn faster. If you make a thermostat change, it takes about 20 minutes for change to take affect. thats why there is about 100 degree variance in the "high" range.

Fattyfat is correct. Running the fan will definitely affect the burn times on the BK. It is -35C or -32F now outside my home. At this temp I run my stove on medium at this temp and the blower on medium. At -20C I run the stove on medium and no blower. Burn times are effected by at least 4hrs.
The fan cools the stove of as it puts more of a load on it. Therefore the the automatic thermostat opens up the damper/primary air to maintain that setting . The mass of the stove is being cooled so the thermostat reacts as Fattyfat has said. Looks like you are getting to know your stove Fatty. Your results sound correct to me Bfunk.
N of 60

 

[Rockey]

That's weird. The blower shouldn't affect your burn time. I think we're not seeing the whole picture.

It does on our stove because the air control runs on a thermostat. when on high, the stove gets up to about 550-650 on top, and automaticaly dampers down to keep stove temps in desired range. cooler stove(ie; blower running) means more air is open and wood will burn faster. If you make a thermostat change, it takes about 20 minutes for change to take affect. thats why there is about 100 degree variance in the "high" range.

Fattyfat is correct. Running the fan will definitely affect the burn times on the BK. It is -35C or -32F now outside my home. At this temp I run my stove on medium at this temp and the blower on medium. At -20C I run the stove on medium and no blower. Burn times are effected by at least 4hrs.
The fan cools the stove of as it puts more of a load on it. Therefore the the automatic thermostat opens up the damper/primary air to maintain that setting . The mass of the stove is being cooled so the thermostat reacts as Fattyfat has said. Looks like you are getting to know your stove Fatty. Your results sound correct to me Bfunk.
N of 60

Yes, on a stove like that it makes perfect sense. The decrease in temperature of the stove indirectly affected the burntime because it directly affected the air intake. On a normal stove I don't see how a blower would affect the burntime.

 

[TMonter]

5+ years no blower here on my 3100i. I always recommend people buy their insert without a blower and purchase it as an option if it doesn't heat like they expect.

 

[LLigetfa]

If you don't let the stove get hot enough for good clean secondary burn, that heat potential will be wasted up the chimney. There has to be a sweet spot where the secondary air is just hot enough.

I use a variable speed fan and I generally don't turn it on until the black formation on the firebrick is burned off, indicating a more optimum burn. I only run the fan on high if the stove is too hot and I'm wasting heat up the chimney.

 

[North of 60]

That's weird. The blower shouldn't affect your burn time. I think we're not seeing the whole picture.

It does on our stove because the air control runs on a thermostat. when on high, the stove gets up to about 550-650 on top, and automaticaly dampers down to keep stove temps in desired range. cooler stove(ie; blower running) means more air is open and wood will burn faster. If you make a thermostat change, it takes about 20 minutes for change to take affect. thats why there is about 100 degree variance in the "high" range.

Fattyfat is correct. Running the fan will definitely affect the burn times on the BK. It is -35C or -32F now outside my home. At this temp I run my stove on medium at this temp and the blower on medium. At -20C I run the stove on medium and no blower. Burn times are effected by at least 4hrs.
The fan cools the stove of as it puts more of a load on it. Therefore the the automatic thermostat opens up the damper/primary air to maintain that setting . The mass of the stove is being cooled so the thermostat reacts as Fattyfat has said. Looks like you are getting to know your stove Fatty. Your results sound correct to me Bfunk.
N of 60

Yes, on a stove like that it makes perfect sense. The decrease in temperature of the stove indirectly affected the burntime because it directly affected the air intake. On a normal stove I don't see how a blower would affect the burntime.

Yes I agree Rocky. The stove with a manual damper would have no affect on the burn time if it is not adjusted as it does not know what is going on. Bfunk has an auto T-stat so Bigreds comment to him does not apply due to his model of stove.

 

[fattyfat1]

Looks like you are getting to know your stove Fatty. Your results sound correct to me Bfunk.
N of 60

Only because of you guy's here. I would be clueless about this stove without this site and it's membership. probably try to run it like my non-cat stove downstairs.

 

[bokehman]

Ok, I see what your saying about removing BTU's faster than a fire can produce it would make the fire go out.

It does go out if the cooling effect is greater than the heat produced. For example if you have ever burned unseasoned wood you will find a big layer of unburned coals in the morning left from when the fire went out. To a lesser extent that happens when you switch the blower on. The box is really hot to start with but the temperature starts to fall. It keeps falling until the number of BTU's being extracted from the box is in equilibrium with the number of BTU's being produced by the fire. If that cooling effect is strong enough it will cool the fire and lower the speed of energy release from the wood (increasing the duration but lowering the output). To keep the box temperature high and run the blower the only way is to readjust the fire to release BTU's faster which means the 50.000 BTU you put in the firebox when you reloaded it will be used up quicker.

Another potential problem when you cool the box with the blower and the fire is not brisk enough is that the internal temp will drop below that needed to maintain secondary combustion.

 

[Rockey]

Ok, I see what your saying about removing BTU's faster than a fire can produce it would make the fire go out.

It does go out if the cooling effect is greater than the heat produced. For example if you have ever burned unseasoned wood you will find a big layer of unburned coals in the morning left from when the fire went out. To a lesser extent that happens when you switch the blower on. The box is really hot to start with but the temperature starts to fall. It keeps falling until the number of BTU's being extracted from the box is in equilibrium with the number of BTU's being produced by the fire. If that cooling effect is strong enough it will cool the fire and lower the speed of energy release from the wood (increasing the duration but lowering the output). To keep the box temperature high and run the blower the only way is to readjust the fire to release BTU's faster which means the 50.000 BTU you put in the firebox when you reloaded it will be used up quicker.

Another potential problem when you cool the box with the blower and the fire is not brisk enough is that the internal temp will drop below that needed to maintain secondary combustion.

Just so I understand you correctly. Your saying that by using a blower it could cause the burntime to be extended. Correct?

 

[jadm]

5+ years no blower here on my 3100i. I always recommend people buy their insert without a blower and purchase it as an option if it doesn't heat like they expect.

If I am not mistaken, your insert extends quite a ways out of your fireplace onto your hearth. My old Napoleon extended out 5" and could be used without the blower.

Last winter I replaced it with the Jotul 550 which is flush to our fireplace. It can be used without the blowers but it doesn't heat up the room very well at all. The insert and the surround get plenty hot but to maximize it's heating potential the blowers, IMHO, are an essential. Having them on doesn't seem to effect burn time. I have experimented both ways and they end up about equal.

Reading through this thread I am reminded once again that different stoves/inserts vary a lot in how they operate. Glad we have a variety of burners here. I am always gleaning information on other 'species' of burning machines. ;-)

 

[kenny chaos]

My burn times with my liberty free standing is the same, blower or not.

 

[LeonMSPT]

There's a few inserts like mine, old VC, with bimetallic springs on the air intake adjustment linkage. Once the insert is up to the temperature I want the blower to blow at, I "bump" the air supply at the limit and go just a strain higher. The fire settles down with the reduced airflow. If the air the blower is pushing across those springs cools, they tighten up and open the air supply until they warm up enough to relax and close the air supply.

Neat set up, and still working well after over twenty years...

So, it would depend on the specific stove as to whether the blower would case burn times to be shorter. Unless I close the air supply past the margin, and allow the fire to smolder and temperature of the blower discharge to go down with the stove temperature.

 

[LLigetfa]

...burner or no burner.

are you drunk?

 

[kenny chaos]

...burner or no burner.

are you drunk?

I'm afraid you've miss quoted me.

 

[Jersey Fire Bug]

I'm confused So now you are saying it is better to run the fan on the "Low" setting and turn
down the damper ? This: in turn, will give me a longer burntime ?

 

[Jersey Fire Bug]

I think I need a reostat...lol

 

[bokehman]

Just so I understand you correctly. Your saying that by using a blower it could cause the burntime to be extended. Correct?

It's not that simple. With the blower off and the steel box at 600F the stove might put out 10,000 BTU per hour. Turn on the fan and the temperature of the box starts to fall. For a few minutes we get a few extra BTU's, not from the fire, but released from storage in the steel. Anyway lets say after a few minutes the temperature stabilizes at 400F. If the fire is unchanged in it's BTU output it is still putting out 10,000 BTU per hour. (i.e. no blower + 600F = blower + 400F = 10,000 BTU per hour.) But here's the thing, you turned on the blower to get more heat. Once you realize the temperature of the box is falling you will respond to get the temperature of the box back to 600F. So you give the fire more air. Now, with the extra air, the steel box is at 600F AND the blower is on. Heat output 15,000 BTU per hour. More BTU's means faster wood consumption.

On the other hand if cooling the steel box with the fan cools the fire it contains that fire will output less BTU's and hence consume the fuel more slowly (if it doesn't go out).

 

[Jersey Fire Bug]

so what is the answer ???? Blower on "Low" or blower on "High" :-S

 

[atvdave]

I think after reading this thread I need to take a few aspirin and go to bed. I'm more confused than before I first read the first post. SO.. Blower on, or NO blower????

 

[LeonMSPT]

Want a long burn time, and maintain temperature of your firebox, want blower on low with air supply adjusted to maintain the temperature in the firebox you want.

Might end up wanting in one hand and pooping in the other though... obviously, the blower will remove heat from the insert faster than convection or radiation, regardless of other explanations. More air moving across the surface of the stove means more heat removed from it. It must be that way according to the laws of physics. You will have to adjust the air supply to the fire to maintain the temperature of the stove, and blower air. The hotter the fire, the shorter the burn, again according to the laws of physics. Except a full out burn in my insert actually cools the thing off and gobbles wood like it's going out of style. Think it's because I cut the secondary air supply a couple years ago.

Connected to a 40 foot tall, inside chimney, with an 8 inch zero clearance liner to the top. Draft is crazy, only way to slow the burn and keep from melting things was to limit the air. Seems to peak now at about 650 degrees wide open... which is where it ends up eventually with gradual increases in the air as the temperature increases and relaxes the bimetal springs in the blower air stream.

 

[LeonMSPT]

Blower or no blower...

Are you cold? If so, turn on the blower and throw an extra log on. If you're real cold, turn it on high and set your alarm, you'll have to get up and feed the dragon.