More air = more heat?

[joecool85]

I've been looking at a Heatilator EcoChoice WS18 and in the manual it lists that high burn (air full open) is 30+K btu, Medium-High is 15-30k btu, Medium 10-15k btu and Low (air closed all the way) 10k or less btu.

But my experience with the 17-VL has been that it heats up quicker and maintains heat better at half or less air - and I've read of others have similar experiences with their Englanders. So, in general, do you get more heat on a secondary combustion stove by damping it down and forcing the secondaries to kick in along with holding more heat in the box as opposed to up the chimney, or do you open the air up and let that baby breath?

 

[begreen]

Haven't burned in this stove but you are correct. In general, a secondary burn stove will burn hotter on the stove top with the primary air restricted.

 

[corey21]

I get the best heat output with the air a smudge open and by that time the secondary burn is cranking out some massive heat. But that is with dry wood in the stove wet wood i cant do that with.

 

[Corey]

In general, for combustion air there should be some 'sweet spot' where you are supplying just enough air to burn the available fuel and the flue gas has enough time to transfer heat to the stove for maximum warmth. To little air and you get a smoky, cold fire, too much air and the airflow itself cools the stove and takes the heat up the flue before it can transfer to the stove.

 

[Huntindog1]

The issue with the air wider open is more air flow thru the stove flushing heat up the flue.

It is harder to build the heat , closing the air down helps build the heat.

 

[joecool85]

So from what you guys are saying, the manual for this stove is at least a little misguiding.

 

[Huntindog1]

I am sure it burns more as you give it more air but more of the Btu's that it lists goes up the chimney and less of it gets out into the room but you burning hotter so wasted heat may not be an issue since your putting out more heat. The manual is right the fire is burning more putting out more btu's but the question is how much of it is flushing up the flue and not heating up your firebox and thus heating up your stove top thus heating your room.

But looking at it form the stand point you first need to build heat in the stove to get to secondary burn mode , you will build heat up in the stove better if at 400 deg stove top temp you incrementally start shutting the input primary air down in 1/4 ways increments then let the fire stabilize from the first reduction of air then reduce it another 1/4 ways. This way for each 1/4 reduction the firebox heats up a little hotter due to the reduced air flow less heat flushing up the flue, ok now your firebox is a little hotter the stove can take another 1/4 way reduction in air and so on. As its the heat building up in the fire box that lets the stove operate at the next lower setting.

 

[bentrice]

The manual is assuming that the stove is fuel rich all the time with zero excess air. If you don't have the fuel to support a wide open inlet damper then your simply flushing the stove's heat up the chimney. Maybe it is a little misguiding because a few coals in the bottom of your stove with air wide open will put the stove out fairly quickly. If you have the stove packed with black locust to the gills with air wide open, yes that is the hottest the stove can fire.

 

[Ashful]

In general, for combustion air there should be some 'sweet spot' where you are supplying just enough air to burn the available fuel and the flue gas has enough time to transfer heat to the stove for maximum warmth. To little air and you get a smoky, cold fire, too much air and the airflow itself cools the stove and takes the heat up the flue before it can transfer to the stove.

What Corey said. Quoted because it's worth repeating. The maximum heat output in a proper setup will be where the primary fire and secondary system are both working together. My stove also runs hottest around 50% on the primary air control, depending on wood load and how it's stacked in the stove.

 

[joecool85]

What Corey said. Quoted because it's worth repeating. The maximum heat output in a proper setup will be where the primary fire and secondary system are both working together. My stove also runs hottest around 50% on the primary air control, depending on wood load and how it's stacked in the stove.

I've found my stove to be similar, it puts out the most heat with the air open between 1/4 and 1/3 of the way. I have a feeling that is the same way that the Heatilator WS18 would run as well. Maybe the BTU labels are for roughly how many BTUs will be burned not expelled into the house necessarily?