Running DIY WoodStove over night in a small cabin & safety issues

[spader]

Don’t worry so much about what is wrong. Have fun playing with it until it runs right.

Just looking over your posts: you seem to be burning small diameter twigs and branches. I’m not sure how that translates.

I’m pretty sure that your stove is designed to burn something like quartered logs 100mm - 120mm wide. It won’t burn through the night on small branches.

I tend to start with small twigs and thin chopped wood harvested and picked up from the back garden. Then when fire builds and going strong, then put in the large logs cut into anything between 50mm - 100mm in diameter.

My wood stoves are in the patio under the canopy shelter, and the other one is by the garden shed under the tarp. So they are never run over night. I tend to run during the late afternoon, and usually the session ends by around 9 - 10pm.

 

[spader]

Does length of flue pipes of woodstove affect burning? For instance, how would 1m length of flue pipe compare with 3m flue pipes off the same woodstove in burning performance?

 

[Pattree]

Very much so up to a maximum. Unfortunately that length is related to the diameter.


[Edited to add:
There is a big difference in “pull” between my tiny stoves. The big one is approx 400mm high in use and the little one 300mm. ]

As mentioned above you are going to have to experiment. You might want to go back to the manufacturers design parameters of your stove and start from there.

After that it’s experiment and research.

This chimney theory is for domestic stoves but their 4-8 KW stove isn’t any bigger than yours. It’s going to take a little effort to sort out.
It should be a fun project.

 

[British Red]

(Deleted as covered by others)

 

[Broch]

Does length of flue pipes of woodstove affect burning? For instance, how would 1m length of flue pipe compare with 3m flue pipes off the same woodstove in burning performance?

It gets a little complicated even without the gas flow maths involved. Basically the longer the flue the more draw is generated by the gases flowing due to the convection. However, the longer the flue the longer it takes to get the system hot enough to create gas flow up to a point where, if the flue is too long, it can stall and you get very little draw (and lots of smoke).

I have about 2.2m of flue using 120mm insulated flue pipe (insulated means it warms up faster) and it smokes for about 5 minutes but then draws just fine. Theory says that my flue is too short for the diameter for a perfect draw. I burn anything from twigs to 60mm in the round or 150mm quartered. the stove is 4.5kw (much bigger than I need in the hut).

 

[Pattree]

If you want to check that your chimney is pulling properly - You can make a perfectly useable manometer with a piece of flexible plastic tube sticking through a piece of cardboard that covers the fire door while the vent is shut tight.

You need a 25mm difference in water level between the two vertical sections of your “u” tube. There is a diagram in the link above.

I’m on holiday this week or I’d make one in about three minutes and photograph it. Perhaps someone else with some clear tube and a bit of garden wire can do it. If not I’ll make one next week.

 

[spader]

Very much so up to a maximum. Unfortunately that length is related to the diameter.


[Edited to add:
There is a big difference in “pull” between my tiny stoves. The big one is approx 400mm high in use and the little one 300mm. ]

As mentioned above you are going to have to experiment. You might want to go back to the manufacturers design parameters of your stove and start from there.

After that it’s experiment and research.

This chimney theory is for domestic stoves but their 4-8 KW stove isn’t any bigger than yours. It’s going to take a little effort to sort out.
It should be a fun project.

So, many factors affect the woodstove operation then. I certainly noticed one day when strong wind was hitting the flue pipe exit hole, smoke was being pushed back into the stove, and the stove was smoking from the front door air vent.

And also recall when woodstove was burning woods without any chimneys in the garden, smoke was far more and made the garden full of smoke.

On the same stove with 2m chimney attached, smoke was far less, and up in the air disappearing into the sky fast.

But I gather that longer chimney might have more pull. I agree with you on the point that wood stove operation is not simple. It involves several factors to run it smooth cleaner burn with more heat and efficiency. And then there is aspects to consider how to make it run all night with less fuel.

It is an art and also science, which involves the theory, knowledge, and practical experience.

 

[spader]

It gets a little complicated even without the gas flow maths involved. Basically the longer the flue the more draw is generated by the gases flowing due to the convection. However, the longer the flue the longer it takes to get the system hot enough to create gas flow up to a point where, if the flue is too long, it can stall and you get very little draw (and lots of smoke).

I have about 2.2m of flue using 120mm insulated flue pipe (insulated means it warms up faster) and it smokes for about 5 minutes but then draws just fine. Theory says that my flue is too short for the diameter for a perfect draw. I burn anything from twigs to 60mm in the round or 150mm quartered. the stove is 4.5kw (much bigger than I need in the hut).

Diameter of the flues will have to be taken into consideration as well suppose. And yes, I recall seeing some folks heating up the flues with a torch when starting the woodstoves.

 

[spader]

If you want to check that your chimney is pulling properly - You can make a perfectly useable manometer with a piece of flexible plastic tube sticking through a piece of cardboard that covers the fire door while the vent is shut tight.

You need a 25mm difference in water level between the two vertical sections of your “u” tube. There is a diagram in the link above.

I’m on holiday this week or I’d make one in about three minutes and photograph it. Perhaps someone else with some clear tube and a bit of garden wire can do it. If not I’ll make one next week.

Sure, I look forward to seeing the demonstration of your device. Thanks.