In Praise of the Undersized Stove - The Oslo Experience

[Todd]

A BTU is a BTU. There is only so much heat available in a load of wood pound for pound and whether it be in a small stove or large stove you will basically get the same amount of heat.

No you won't. While the firebox in the big boy is getting up to secondary burn temps the little boy has been there for a while already. With the big boy those BTUs are going up the stack.

Ok, I see what your getting at, If it was a dead cold start I can see your point, but if the two stoves already have a bed of coals it won't take much difference between them to reach that secondary burn.

 

[BrotherBart]

A BTU is a BTU. There is only so much heat available in a load of wood pound for pound and whether it be in a small stove or large stove you will basically get the same amount of heat.

No you won't. While the firebox in the big boy is getting up to secondary burn temps the little boy has been there for a while already. With the big boy those BTUs are going up the stack.

Ok, I see what your getting at, If it was a dead cold start I can see your point, but if the two stoves already have a bed of coals it won't take much difference between them to reach that secondary burn.

And the little one with secondary burn will warm keep ya warm. The big one will have you sleeping in the garage. :lol:

The issue is heat transfer. Kinda simple, but hey, I haven't argued on this forum since Elk and me used to duke it out over the need for block off plates.

 

[jotul8e2]

This was my first year with this model & with wood stoves in general & was quite happy. Never did achieve the elusive 9hr burn either. Always had coals in the morning but the stove was not putting out anything substantial (heat wise) after 4-5 hrs. That was a bit of a dissapointment. The other thing is I need to figure out how to get the heat into the other rooms, on cold nights you could feel a bit of a nip in them.

Based on my decades of experience with an Efel (pre EPA), a Dutchwest Large (cat), and my parent's Hearthstone (also pre EPA), to say I would have been surprised had I been able to get a true 8 hour burn with the Oslo is a considerable understatement. All I really hoped for was a good coal bed to relight in the morning or after coming home from work.

However, you can do somewhat better than four hours. Using at least one unsplit log of 5"-6" diameter helps. But the real key is filling the firebox. The Oslo firebox is very long - 24": if you stack it full of 16" stuff it simply will run out of fuel 1/3 short of capacity. Of course getting the right air intake is critical as well.

Getting warm air to other rooms appears to involve a combination of science, luck, and art. There are two big issues here: First, most houses have a foot or more of wall above their connecting doors. This blocks the movement of warm air across the ceilings. 19th and early 20th century builders understood this and installed transoms. The other issue is the fact that a wood burning stove generates a very low volume of heated air, which moves very slowly by natural convection. This means that without really good insulation the heat can easily dissapate through the ceilings and walls before it has a chance to warm up the space as we would like. We do not observe this with central heating systems as the volume of air flow is very high, warming the space quickly. Many different combinations of ceiling fans, box fans, ventilation grills, and so forth have been tried, and most are described somewhere on these forums.

My house heats pretty evenly. I designed it do do so, but even at that we were fortunate to get it to work as well as it does. I have five openings off our family room (stove location), none less than 48" wide, and all open to the ceiling. But the real difference maker is the insulation - R50 + in the attic, r30 in the walls, no 20' atriums, no "glass walls", all over a full basement with 1 1/2" foam between the concrete and the dirt. Heat simply does not "leak out" very fast.

Mark

 

[Todd]

A BTU is a BTU. There is only so much heat available in a load of wood pound for pound and whether it be in a small stove or large stove you will basically get the same amount of heat.

No you won't. While the firebox in the big boy is getting up to secondary burn temps the little boy has been there for a while already. With the big boy those BTUs are going up the stack.

Ok, I see what your getting at, If it was a dead cold start I can see your point, but if the two stoves already have a bed of coals it won't take much difference between them to reach that secondary burn.

And the little one with secondary burn will warm keep ya warm. The big one will have you sleeping in the garage. :lol:

The issue is heat transfer. Kinda simple, but hey, I haven't argued on this forum since Elk and me used to duke it out over the need for block off plates.

Uncle

 

[BrotherBart]

Uncle

Dang'it. I had planned to be the one to give up first!

 

[snowtime]

Well Brother my impression is you are talking about poorly insulated or sealed homes. Our 1 fire a day is not a full load as that would be to much heat. Just a 2/3 load gets the house up to 70 on a mild day [25f to 30f] and it stays close to that for 24 hours. We lose about 4 degrees by the next morning. I call that a winning combo. The key is a superiorly insulated home. No one is saying that 1 fire will go for hours on end but if your house is tight and insulated well it should hold the heat overnight no problem as long as the outside temps are not too serious.
Its not how many BTUs you have but how you preserve them. Now if someone runs a short hot fire and gets the house up to 70+ and the house cools down below say 60 by the next day I say the house is not that well insulated or has some other heat lose area such as poor windows.
Cold weather is a hole nuther thing. But I think someone planning to heat only with wood would be better served with a bigger not smaller stove. Better to have the heat when you need it and learn to burn small when you do not. If someone has power and backups then they are safe and can play with getting the stove that will "mostly" match the conditions and just augment when its cold. Just my thoughts for having a good flexible stove.

 

[Deep Fryer]

Based on my decades of experience with an Efel (pre EPA), a Dutchwest Large (cat), and my parent's Hearthstone (also pre EPA), to say I would have been surprised had I been able to get a true 8 hour burn with the Oslo is a considerable understatement. All I really hoped for was a good coal bed to relight in the morning or after coming home from work.

Getting warm air to other rooms appears to involve a combination of science, luck, and art. There are two big issues here: First, most houses have a foot or more of wall above their connecting doors. This blocks the movement of warm air across the ceilings. 19th and early 20th century builders understood this and installed transoms. The other issue is the fact that a wood burning stove generates a very low volume of heated air, which moves very slowly by natural convection. This means that without really good insulation the heat can easily dissapate through the ceilings and walls before it has a chance to warm up the space as we would like. We do not observe this with central heating systems as the volume of air flow is very high, warming the space quickly. Many different combinations of ceiling fans, box fans, ventilation grills, and so forth have been tried, and most are described somewhere on these forums.

I have five openings off our family room (stove location), none less than 48" wide, and all open to the ceiling. But the real difference maker is the insulation - R50 + in the attic, r30 in the walls, no 20' atriums, no "glass walls", all over a full basement with 1 1/2" foam between the concrete and the dirt. Heat simply does not "leak out" very fast.

Mark

Hi Mark!

Thank you for your input regarding this subject, you've certainly allayed a lot of my concerns. Bottom line is I am very happy with the stove & the whole experience of heating with wood.
This year I opened up the wall (10'+ opening) between the kitchen & the dining room which also opens to the living room, so now I have a very open sort of layout which should help a bit. I also replaced a lot of windows in the LR & DR areas, the stove is located in the LR.
I plan on redoing the insulation this fall & maybe come up with some transom ideas. One of my biggest issues remaining is that I have a set of stairs directly in front of the stove & although there is a ceiling fan about 5' in front of the stove, either the fan moves the heat against the stove to the opposite side of the house or if the fan is off all the heat goes right up the stairs.


Looking forward to next season, ;-)
& depending on how things work out I may consider the bigger model, I can always put the olso in the bedroom :lol:

 

[karri0n]

DF,

You should try reversing that fan with the winter/summer switch so instead of pushing the ceiling air downwards, it pulls the air coming off the stove upwards. The stove itself has warm air coming off of it, fan or not. Heating the air causes it to move naturally. With the fan blowing down, you are mostly causing turbulence in the room. If you reverse the fan so the air goes up towards the ceiling, it will instead spread in a circular radius around the fan, hit the walls of the room, and travel down them. This will make the warm air go in doorways since the air will be moving downward at the walls when it hits the top of the doorframe, rather than just causing air turbulence 5' in front of the stove.

 

[Deep Fryer]

Hi KO!
Your suggestion is right on the money as I did some experimenting at the beggining of the season & it is exactly as you said.
The ceiling fan was most efficient when it was switched to reverse air flow.

;-)

 

[webby3650]

DF,

You should try reversing that fan with the winter/summer switch so instead of pushing the ceiling air downwards, it pulls the air coming off the stove upwards. The stove itself has warm air coming off of it, fan or not. Heating the air causes it to move naturally. With the fan blowing down, you are mostly causing turbulence in the room. If you reverse the fan so the air goes up towards the ceiling, it will instead spread in a circular radius around the fan, hit the walls of the room, and travel down them. This will make the warm air go in doorways since the air will be moving downward at the walls when it hits the top of the doorframe, rather than just causing air turbulence 5' in front of the stove.

I tried this theory, with MY floorplan it made no difference. I closely monitor temps. in the bedrooms and found no difference, if anything it took longer to warm up the outer rooms! So, the point is, always experiment(as long as it is safe), just because it worked well for someone else doesn't mean it is the way to do it. That is the best thing about burning your experiment, you can always try again! :coolsmile:

 

[MountainStoveGuy]

A BTU is a BTU. There is only so much heat available in a load of wood pound for pound and whether it be in a small stove or large stove you will basically get the same amount of heat.

No you won't. While the firebox in the big boy is getting up to secondary burn temps the little boy has been there for a while already. With the big boy those BTUs are going up the stack.

Ok, I see what your getting at, If it was a dead cold start I can see your point, but if the two stoves already have a bed of coals it won't take much difference between them to reach that secondary burn.

And the little one with secondary burn will warm keep ya warm. The big one will have you sleeping in the garage. :lol:

The issue is heat transfer. Kinda simple, but hey, I haven't argued on this forum since Elk and me used to duke it out over the need for block off plates.

block off plates? who uses block off plates anymore?? :zip:

 

[BrotherBart]

block off plates? who uses block off plates anymore?? :zip:

Welcome back my friend. Both to the Forum and to selling big boxes for toasting trees. Missed ya.

 

[bigfire]

block off plates? who uses block off plates anymore?? :zip:

Welcome back my friend. Both to the Forum and to selling big boxes for toasting trees. Missed ya.

Gee whillikers Big Bart, can you miss anyone else ? What do you do with your time besides this internet thing ?

 

[begreen]

Gee whillikers? Is that you Gomer?