Wood Burning Stoves

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Zasso Nouka
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Post by Zasso Nouka »

Tora wrote:
Sat Oct 22, 2022 11:31 pm
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.
I like to think I've got asbestos hands but sounds like yours are way tougher than mine :lol: I can kind of hover my hand over the single walled flue section that comes out of the stove but there's little to no chance of getting really close or even touching it :lol:
KumamotoHunter wrote:
Mon Oct 24, 2022 11:56 am
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.


Maybe it's time to invest in one of those, we never bought one before and like you thought if it looks dry on the outside it's probably fine on the inside so it might be good to actually know how dry the centre of a log is.

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Post by Tora »

Zasso Nouka wrote:
Mon Oct 24, 2022 12:23 pm

I like to think I've got asbestos hands but sounds like yours are way tougher than mine :lol: I can kind of hover my hand over the single walled flue section that comes out of the stove but there's little to no chance of getting really close or even touching it :lol:


I know people who think they should touch a 1000 degree blob of molten glass to get rid of a sliver of glass they got stuck in them. I prefer a piece of sticky tape!

Our stove seems to do a good job of extracting a lot of the heat- is why I think the stove pipe is cool enough to touch. Or maybe I’m just insensitive….
Zasso Nouka wrote:
Mon Oct 24, 2022 12:23 pm
Maybe it's time to invest in one of those, we never bought one before and like you thought if it looks dry on the outside it's probably fine on the inside so it might be good to actually know how dry the centre of a log is.
I’d like to hear your opinion if you get one of these. I’ve been wanting one of these but wifey gives me dirty looks whenever I suggest buying something she can’t eat!

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Post by Washoi »

I have a moisture meter, they are very cheap and easy to use, just make sure you select the correct wood for your test. I.e. don't select pine for some oak. They're useful in my opinion.

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Post by Otona Cream Pie »

Most of those SHARP plasma cluster humidifiers have humidity monitors and add humidity as needed. They are pretty wonderful.

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Post by Savot »

Zasso Nouka wrote:
Sun Jun 05, 2022 6:00 am
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:
We've had a couple of snowy nights here with only the heat of the stove to keep us warm, so I though it would be a good time to report back on how the Nectre Mk 1 has fared.

We first fired it up a month or so ago and it initially made the house uncomfortably hot. We were also using an inordinate amount of wood. Once I gained a bit more control over the air intake and loading process we were able to easily maintain a comfortable temperature in 10C weather.

It's recently got a bit colder, around 0C min, and the stove has kept the house at about ~24C downstairs and ~18C upstairs. The performance might have be helped along by the insulation, but it definitely keeps the house significantly warmer (and more uniformly heated) than kero heaters. There are a couple of extraction fans near the stove that currently lead outside (probably to get rid of CO from a kero heater), that I'd like to redirect upstairs to try and equalise the upstairs and downstairs temperatures.

While it heats the house well we have noticed a few issues. We're still using quite a bit of wood, which I've had to buy because the wood I stockpiled hasn't dried enough yet. Hopefully this will be less of an issue once I gather and dry enough to be a season or two ahead. Using the stove can also be dirty, with ash and bits of wood around the hearth making a mockery of the concept of not bringing dirt into a Japanese house. It also takes a bit of time to get the fire going and to heat up the house in the morning (~1 hour). I'm hoping to source enough hardwood to be able to burn overnight. The most annoying issue though is the occasional smoke blowback we get. I installed the chimney myself, and I'm pretty sure this happens because I used single-wall for the outside section and the chimney is not quite high enough (the geography in my area also doesn't help). We're using a blowtorch to heat up the chimney before lighting a fire in the morning, which helps.

All-in-all, we're very happy with how things have worked out. With the subsidy for the local government the total cost was only 30 man. I think we could have gone for more expensive stove and/or chimny but I'm not sure the benefit would have been worth the extra cost.

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Post by Zasso Nouka »

Glad to hear the stove is working well for you, that's some pretty toasty temperatures you've got there.
Savot wrote:
Sun Dec 04, 2022 7:17 pm
We first fired it up a month or so ago and it initially made the house uncomfortably hot. We were also using an inordinate amount of wood. Once I gained a bit more control over the air intake and loading process we were able to easily maintain a comfortable temperature in 10C weather.
If you are burning softwood then your stove will go through that fairly quickly. We normally start the evening off with sugi or hinoki and when the air vent is fully open it will consume the wood quite quickly but it heats the house up quickly as well.
Savot wrote:
Sun Dec 04, 2022 7:17 pm
There are a couple of extraction fans near the stove that currently lead outside (probably to get rid of CO from a kero heater), that I'd like to redirect upstairs to try and equalise the upstairs and downstairs temperatures.
That would be a neat idea if you can easily run some ducting upstairs.
Savot wrote:
Sun Dec 04, 2022 7:17 pm
The most annoying issue though is the occasional smoke blowback we get. I installed the chimney myself, and I'm pretty sure this happens because I used single-wall for the outside section and the chimney is not quite high enough (the geography in my area also doesn't help). We're using a blowtorch to heat up the chimney before lighting a fire in the morning, which helps.
I don't know what the feasibility would be of insulating the outside section with rockwool or something or even if it would pose a fire hazard or not. In theory rockwool isn't flammable but whether you'd want to risk a fire on that basis I can't say. Having a single walled outside chimney run not only can lead to smoke blowback but it can also damage your stove because the steam produced even when burning properly seasoned wood will condense on the outside part of the chimney and produce far more runny creosote that can drip down the chimney and corrode your stove leading to a shortened lifespan of the stove. "Dry" creosote tends to stay where it is and isn't so chemically active, specially when paired with a creosote remover that changes the chemical make up.

A tip when lighting the fire initially is to lightly crumple 2 or 3 sheets of newspaper and place them on top of the kindling. They will burning quickly warming up the chimney so the fire starts drawing faster and you get less creosote condensing in the initial stages when the chimney is still cool.
Savot wrote:
Sun Dec 04, 2022 7:17 pm
All-in-all, we're very happy with how things have worked out. With the subsidy for the local government the total cost was only 30 man. I think we could have gone for more expensive stove and/or chimny but I'm not sure the benefit would have been worth the extra cost.
Sounds pretty good and glad you are happy with it. Whether upgrading the outside section is worthwhile or not only you can say but it might be worth monitoring the creosote in the lower sections of the chimney and if you are getting runny wet rather than dry crusty creosote there it might be worth doing. Although expensive it might work out cheaper than shortening the useful lifespan of your stove. Or you may find that somewhat more regular use of a creosote remover may harden it to a more dry and crusty texture that doesn't drip down into your stove and not need to upgrade the outside section.

Best of luck and hope you enjoy a warm winter season. I can wholeheartedly recommend slow cooking spare ribs over a few hours on a wood stove, the meat practically falls off the bone and the smell as it's cooking is wonderful :dance:

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Post by Zasso Nouka »

I just read this article

How firewood burns and apart from an interesting discussion on how wood actually burns in a stove it mentions that if the chimney isn't hot enough you can get carbon monoxide blowback as well as smoke blowback which is definitely something you want to avoid.

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Post by Tora »

Savot wrote:
Sun Dec 04, 2022 7:17 pm

While it heats the house well we have noticed a few issues. We're still using quite a bit of wood, which I've had to buy because the wood I stockpiled hasn't dried enough yet. Hopefully this will be less of an issue once I gather and dry enough to be a season or two ahead. Using the stove can also be dirty, with ash and bits of wood around the hearth making a mockery of the concept of not bringing dirt into a Japanese house. It also takes a bit of time to get the fire going and to heat up the house in the morning (~1 hour). I'm hoping to source enough hardwood to be able to burn overnight. The most annoying issue though is the occasional smoke blowback we get. I installed the chimney myself, and I'm pretty sure this happens because I used single-wall for the outside section and the chimney is not quite high enough (the geography in my area also doesn't help). We're using a blowtorch to heat up the chimney before lighting a fire in the morning, which helps.

All-in-all, we're very happy with how things have worked out. With the subsidy for the local government the total cost was only 30 man. I think we could have gone for more expensive stove and/or chimny but I'm not sure the benefit would have been worth the extra cost.
Sounds like your stove is helping you stay comfy.

One hour to heat your house up isn’t bad. We have earthen interior walls that take a long time to warm up so it takes a half day if we’ve been a way for a while in winter. Those walls also hold heat after the stove cools off so they definitely help balance out temperature.

If you load more small pieces you’ll get a hotter fire quickly and that will help heat your house more quickly. It will also get your stove hotter and risks over fire so keep an eye on things. I save my itty bitty bits and pieces from chopping and trimming and put them in a box or an old envelope I can throw in easily. That’s how one friend puts his junk mail to good use.

Using (a) circular fan(s) is a good way to direct heat where you want it or just even out high and low temp areas. You can also close doors to rooms/areas you don’t plan to use soon so you can concentrate heat on the areas you want to warm up faster.

We have a similar single walled stove pipe to yours. We also get occasional back draft on very windy days with a small fire or when we’re trying to start it and there is an exhaust fan running somewhere in the house- easily resolved by turning off the fan or opening a window for a few minutes till there is a good fire pulling hot air up the chimney.

Upgrading to double walled pipe is something I want to do for the exterior section but it is an investment.

We have the liquid creosote issue Zasso spoke of. I created a slight grade in the horizontal section where the pipe passes through the wall so any liquid will flow away from the stove and drip (into a bucket I save to spay on trees and garden pests) from the outside elbow. That liquid was saturating the dry creosote buildup which caused a horizontal section of “stainless” steel stovepipe to rust after 4-5 years of use. There was also rain entering where the pipe sections joined.

I replaced that section of rusted horizontal pipe with a spare piece I had and caulked the exterior joints with high temp silicone this year (I suspect regular silicone would work at those temps but didn't want to push my luck any more). I also drilled a small hole at the bottom of the outside elbow to help any liquid get out faster. I plan to clean out any dry creosote from the horizontal section where it passes through the exterior wall more often- probably should do that tomorrow.

That got quite long but it might be of use to someone.

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Post by Zasso Nouka »

I imagine that most of us who have installed a wood stove thought we had found an environmentally friendly way to heat our homes, we're not using fossil fuels but something renewable. The CO2 produced would be absorbed by trees and recycled and we would improve the internal environment of our homes with a nice warm glow but sadly it increasingly seems to not be the case.

There was an interesting read from George Monbiot in The Guardian recently My burning shame: I fitted my house with three wood-burning stoves that challenges these assumptions. For anyone unfamiliar with George Monbiot he isn't some anti green radical but is actually an environmental and political activist.

It's a relatively short article and well worth reading but the main takeaways are that wood stoves produce more pollution than heavy goods vehicles (up to 750 times the amount of fine particulates :eek: :shock: ). They also pollute the inside of our homes with fine particles which can exacerbate asthma or other respiratory conditions. Apparently in the UK now wood stoves produce more fine particulate pollution than all the cars and lorries even though they are only used in 8% of homes :eek: , that's a pretty sobering statistic.

Not advocating ripping out your wood stove, we're certainly going to carry on using ours but will be more mindful in how we use it. No more turning the airflow down really low at night so it lasts till the morning, just load it up to the max with hardwood and bring the coals back to life when we get up. Cracking the door open a little when loading and holding it there before slowly opening it fully so as to establish a positive inwards movement of air to minimise how much ash or dust comes into the house. Only ever burning fully seasoned wood and not trying to get away with something that's a little damp. Perhaps even going so far as to wear a PM2.5 proof surgical mask when cleaning the stove out, although that does seem excessive.

Anyway something to think about perhaps.

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Post by Tora »

It’s something to consider for sure. If that’s the case, though, everyone living in the inaka is screwed when the locals get a gumption to burn brush or leaves or weeds or … trash….

I do wonder what the author of that article is doing wrong if he’s getting smoke in his face every time he opens his stove. It reminds me of a neighbor who bought a cheap tin can stove at the home center and was burning it with the door open to get more heat. He said his white dog turning gray inspired his son to buy him a carbon monoxide detector for Christmas.

I have heard that a number of people in the UK burn coal in their stoves as well as wood. I wonder if that is included in their assessment or if it’s just based on wood.

I am guessing by “particles (ppm)” he’s referring to smoke. I know we get a little smoke when starting up or adding new wood but otherwise no smoke to speak of. So, I wonder if the numbers are from an average burn from a modern stove, starting up, poorly burning stoves, old stoves, fireplaces, etc.

It’s definitely something I’ll keep my eyes open to in the future.