Wood Burning Stoves

A forum for DIY, cars, pets and all things related to home life
User avatar
Zasso Nouka
Tech Support
Tech Support
Posts: 5656
Joined: Wed Sep 23, 2015 9:37 am
Location: Chiba Prefecture
Has thanked: 4129 times
Been thanked: 3549 times

Wood Burning Stoves

Post by Zasso Nouka »

It's a complex area working out the exact heat output of a wood stove I guess as opposed to gas or electric heating, so many variables.

Looking forward to hearing how you get on with the Nectre Mk 1 when you have a chance to fire it up, it does look like a very nice wood burner :dance:

User avatar
KumamotoHunter
Posts: 95
Joined: Sat Feb 25, 2017 12:33 pm
Has thanked: 56 times
Been thanked: 173 times

Wood Burning Stoves

Post by KumamotoHunter »

I moved this post to "Firewood" from here. Sorry!
Last edited by KumamotoHunter on Tue Oct 18, 2022 1:12 pm, edited 2 times in total.

User avatar
KumamotoHunter
Posts: 95
Joined: Sat Feb 25, 2017 12:33 pm
Has thanked: 56 times
Been thanked: 173 times

Wood Burning Stoves

Post by KumamotoHunter »

This is my flue pipe, newly installed last month (the last one was 25 years old, and in terrible shape!):
https://ibb.co/4MHSbzv
Image

https://ibb.co/3F3xCPq
Image

It is all single-wall (0.8mm?) type. Double-wall pipe was insanely priced.
What you see in the above two photos cost 350,000 yen (including labor for installation)!
As you can see, I have 90 degree bends both inside and out.
Annual outside temperatures are in the range of about -10c to +35c in the run of a year.
I clean it once a year. I don't get much creosote build-up as I burn well-seasoned wood.
The draft is good!
I also use this stuff regularly:
https://ibb.co/vYFZRvH
Image

User avatar
Zasso Nouka
Tech Support
Tech Support
Posts: 5656
Joined: Wed Sep 23, 2015 9:37 am
Location: Chiba Prefecture
Has thanked: 4129 times
Been thanked: 3549 times

Wood Burning Stoves

Post by Zasso Nouka »

Looks great. Are there any disadvantages to using single wall flue ? You probably get a lot more heat out into the room rather than using double wall for a lot of it.

edmundedgar
Posts: 72
Joined: Sat Feb 08, 2020 4:14 pm
Has thanked: 73 times
Been thanked: 177 times

Wood Burning Stoves

Post by edmundedgar »

Zasso Nouka wrote:
Fri Oct 21, 2022 8:16 am
Looks great. Are there any disadvantages to using single wall flue ? You probably get a lot more heat out into the room rather than using double wall for a lot of it.
IIUC if you only have a single wall the inside of the metal doesn't stay as consistently hot, so you get more gunk stuck to it. I guess this is less of an issue if you have nice wood and burn it properly hot.

User avatar
Zasso Nouka
Tech Support
Tech Support
Posts: 5656
Joined: Wed Sep 23, 2015 9:37 am
Location: Chiba Prefecture
Has thanked: 4129 times
Been thanked: 3549 times

Wood Burning Stoves

Post by Zasso Nouka »

edmundedgar wrote:
Fri Oct 21, 2022 4:39 pm
IIUC if you only have a single wall the inside of the metal doesn't stay as consistently hot, so you get more gunk stuck to it. I guess this is less of an issue if you have nice wood and burn it properly hot.
That's what I'd been told but sounds like it's not a problem for @KumamotoHunter. Perhaps because we mostly burn sugi and hinoki we end up cleaning our chimney 2 or 3 times a year.

User avatar
KumamotoHunter
Posts: 95
Joined: Sat Feb 25, 2017 12:33 pm
Has thanked: 56 times
Been thanked: 173 times

Wood Burning Stoves

Post by KumamotoHunter »

Zasso Nouka wrote:
Fri Oct 21, 2022 5:37 pm
edmundedgar wrote:
Fri Oct 21, 2022 4:39 pm
IIUC if you only have a single wall the inside of the metal doesn't stay as consistently hot, so you get more gunk stuck to it. I guess this is less of an issue if you have nice wood and burn it properly hot.
That's what I'd been told but sounds like it's not a problem for @KumamotoHunter. Perhaps because we mostly burn sugi and hinoki we end up cleaning our chimney 2 or 3 times a year.
The issue is the external run of the flue; that should really be double-walled. It stops the cold air outside from causing the temperature inside the flue to drop. This sudden drop in temperature causes creosote to precipitate on the inside of the flue. Inside the house, single is preferable as it radiates a lot more heat out.
I only burn well-seasoned wood, both softwood (cedar) and hardwood (chestnut/cherry/oak). I clean the chimney once a year, and that is sufficient. Well-seasoned wood in combination with the Rutland product I posted above helps to reduce creosote build-up.
People say you shouldn't burn cedar, but as long as it is well-seasoned it is perfectly fine.

User avatar
Zasso Nouka
Tech Support
Tech Support
Posts: 5656
Joined: Wed Sep 23, 2015 9:37 am
Location: Chiba Prefecture
Has thanked: 4129 times
Been thanked: 3549 times

Wood Burning Stoves

Post by Zasso Nouka »

KumamotoHunter wrote:
Fri Oct 21, 2022 8:27 pm
People say you shouldn't burn cedar, but as long as it is well-seasoned it is perfectly fine.
That's what you always read on wood burning forums but it's mostly what we have and like you say so long as it is properly dry it burns perfectly fine. Like you we use the Rutland creosote remover. Our main issue is not the flue but the cowling at the top of the chimney, that gets a flaky bubbly dry residue that builds up and needs removing yet when you look down the flue it's fine with just a little powdery build up on the walls but as I'm already up on the roof might as well shove the brushes down the chimney.

Tora
Posts: 485
Joined: Tue Apr 24, 2018 8:53 am
Has thanked: 279 times
Been thanked: 837 times

Wood Burning Stoves

Post by Tora »

I second what @kumamotohunter said about the single wall stovepipe. I clean mine once or twice a year. We also get some condensation and resultant drip from the elbow on the outside section. I just catch and bottle that (mokusakueki) and spray it around the perimeter of the foundation to discourage centipedes and in the garden and fruit trees for bugs. I think if works but it’s likely that the soap and occasional chili pepper I put in the spray are the real active ingredients.

We do get an occasional puff of smoke from the stove on really windy days when the stove is not at least medium hot. We do have a lot of trees and a hill near where the chimney exits the house so swirling winds can be an issue. I don’t know if that’s something double walled pipe would resolve.

I may replace the 2m outside section with double walled pipe at some point.

I did have to replace the horizontal section of cheap “stainless” stovepipe as it had rusted through in one spot after 3-4 years of use. I suspect part of that is my fault for not properly cleaning and capping the chimney and caulking the seams in the stovepipe to keep out all blowing rain in the late spring. We had some heavy rain storms that brought rain into the stove pipe, apparently. Caulking the seams with high temp silicone seemed to make a big difference. I wish the caulking was black (not gray!) as the stovepipe is black too.

I can actually touch the single walled pipe briefly (3 seconds without burning sensation) right before it goes through the wall about 160cm from where it leaves the stove when it’s burning at medium heat. I’m used to using sense of touch for judging temperature for my work. I don’t recommend it to people who don’t know what they’re doing and/or willing to take responsibility for their own actions. That’s my disclaimer.

User avatar
KumamotoHunter
Posts: 95
Joined: Sat Feb 25, 2017 12:33 pm
Has thanked: 56 times
Been thanked: 173 times

Wood Burning Stoves

Post by KumamotoHunter »

The little moisture meter I bought from Amazon is really useful.
I often split a piece of wood I think is ready to burn (measures less than 20% on the outside), only to get a reading of 35% or so on the inside. Makes me wonder how much wood I've been burning which was actually over 20% water in years gone by. :eek:
This alone makes a huge difference to build-up inside the flue.