Wood stove use and health

[Ctwoodtick]

My wood insert has had some issue with smoke/ash floating into room when I open door for the 12 years I’ve had it. I’m currently working on fixing the draft and will be doing a test with some lengths of duct pipe to see if extra height for chimney helps.
Coincidentally, I just found out that I have very early coronary artery disease.
Not sure what exactly I’m asking here, but curious how other people with similar health stuff deal with stoves/smoke etc. Of course I look online and it’s doom and gloom, so I wanted to see what some down to earth thoughts are on this from you all.
I love using wood heat and woukd never want to give it up.
Thanks in advance!

 

[Dieselhead]

As far as I’m concerned a little ash and smoke won’t kill ya as long as it’s from clean wood. People cook with charcoal and smokers that’s probably a lifetime from your woodstove in a couple meals. People stand around campfires and the same, lots inhaled in a single setting compared to what’s in your house. I imagine smoke isn’t banked down in the stove room more of an odor. Think of firemen working forest fires, usually the cancer firemen get are from their gear, foam and house fire type smoke not the clean wood smoke. I’m not a doctor and I’m sure one would disagree with me but these are just my thoughts and beliefs.

 

[Eman85]

Anything past clean air can't be good for us. Like many things we can tolerate a lot if done in moderation. Unfortunately once we become compromised we need to moderate a lot more. One thing I've noticed is I'm more sensitive to irritants the older I get, never sneezed so much or had a runny nose like I do now.

 

[GG Woody]

My wood insert has had some issue with smoke/ash floating into room when I open door for the 12 years I’ve had it. I’m currently working on fixing the draft and will be doing a test with some lengths of duct pipe to see if extra height for chimney helps.
Coincidentally, I just found out that I have very early coronary artery disease.
Not sure what exactly I’m asking here, but curious how other people with similar health stuff deal with stoves/smoke etc. Of course I look online and it’s doom and gloom, so I wanted to see what some down to earth thoughts are on this from you all.
I love using wood heat and woukd never want to give it up.
Thanks in advance!

I'll defend your wood stove, but I'm not a doctor...
I get a LOT of fresh air when I'm dealing with wood outside/in the forest/in the yard, every time I open the door to bring in wood I get even more fresh air, the stove will even draw fresh air into the house as it burns! It's also my gym pass...
Obviously, it's smoke and mirrors, and or purely coincidental, but there are sure a lot of stories like "My grandpa was 110 years old and burned wood all his life"
Burning wood seems like an extremely healthy life choice to me.
Did I mention that I'm not a doctor...
Best of luck with your health, glad to hear that you have caught it early.

 

[Nordicbynature]

I really recommend everybody to get an air purifier, if you are running a wood stove.

It is low cost and will not do you any harm to have an air purifier.

Our air purifier measures and shows the particles in the room. The values spikes every time I open the door to through in some logs. I can see how the air purifier does its job and filters the particles within short.

 

[DrfluffyMD]

Air purifer.

Also, consider burn in a way to not have to reload and supplement with other type of heat in between.

 

[Ctwoodtick]

I really recommend everybody to get an air purifier, if you are running a wood stove.

It is low cost and will not do you any harm to have an air purifier.

Our air purifier measures and shows the particles in the room. The values spikes every time I open the door to through in some logs. I can see how the air purifier does its job and filters the particles within short.

Thanks for the advice. I starting using the one that I had sitting in the basement for a while just recently. It doesn’t have a read out of how bad the air is, but has a green yellow and red indicator so I can see it spiking when it is.
Do you recommend keeping in the same room as stove, or is a bit of distance from stove better? I currently have mine about 10 feet away from stove.

 

[John Lehet]

Definitely keep working on the chimney. I’m don’t know anything about inserts, but I wonder if it’s also possible to find one that is less prone to dumping ash and smoke.

All the stoves I’ve had in this house over the last 18 years (3) have not let any smoke into the house. The current stove with hot-swapable ash pan doesn’t even contribute any ash to the house. None. Last two stoves did indeed put a lot of ash into the air and surfaces. The ash pan I’ve got now (slide out and cover it) along with the hinged smoke blocking metal at the door keep it really clean.

We have air purifiers up and downstairs with indicators for whatever that’s worth, and our air inside is always actually cleaner in winter than often in summer (distant wildfires).

Last night I went to a meeting in a part of town named after a hollow, and it really is a hollow. Air settles in there. The smoke outdoors — yuck. That little area needs everyone to get clean modern stoves. If you lived there you’d need indoor air purifiers even if you didn’t burn wood.

You can also get indoor pm 2.5 meters from purpleair and other places. It’s the PM2.5 you’ll be worried about if you are worried about heart/lungs/blood vessels. Get a measuring instrument and then you don’t have to guess.

 

[Nordicbynature]

Thanks for the advice. I starting using the one that I had sitting in the basement for a while just recently. It doesn’t have a read out of how bad the air is, but has a green yellow and red indicator so I can see it spiking when it is.
Do you recommend keeping in the same room as stove, or is a bit of distance from stove better? I currently have mine about 10 feet away from stove.

I have my air purifier about the same distance away from the stove in the same room. Let's call it 10 feet from the wood burning stove.

Below a measurement. You can see the particle concentration in the room is generally very low, although we heat the house with a wood burning stove and we have a pellet stove in another room which we run when we are not at home.

The graph shows start up at around 15:00 (3 PM) and reload at around 22:00 (10 PM). You can see the particle concentration going down rapidly. At start up I need to have the stoves door slightly open, that is why the period is longer.

PM1 are the smallest particles. Normally PM2.5 is reported. You can see in the graph, that opening the stoves door brings the indoor air quality from very good to moderate.

I have a very "aggressive" baffle plate.

I have a mini-split running in fan mode distributing the heat from the stove through the house. The filters take the bigger dust particles.

 

[DBoon]

An AirThings monitor will report PM2.5, PM1 and VOC levels. I really recommend this device. I reports a 24-hour average radon level as well. It's about $300.

I have been tracking my PM2.5 and VOC levels and modifying burning techniques this year to understand what I should do differently. I was going to create a new post, but this is a good post to add this info to.

In general, I am finding that less than optimally dry wood definitely impacts PM2.5 and VOC levels more than anything else. These levels can rise to "not good" (but I wouldn't characterize them as "dangerous") levels during some phases of the burn. PM2.5 tends to peak in a short window (sometimes, with wetter wood) of about an hour or so. VOCs increase as coaling stage begins and can increase very rapidly and stay elevated for three to four hours before decreasing. My (average) sense of smell cannot detect these levels, which makes the AirThings monitor helpful to have. If VOCs get to a higher level than I'd like, I open the a window downstairs and a window upstairs to get some extra (additional to the heat-recovery ventilator) air-changes into the house.

PM2.5 I am not too worried about - the peak during during is shorter, doesn't happen all the time, and will happen less as my wood is more reliably 3-years dried, stacked in single rows, and without water penetrating the top cover (I am using better tarps, old EPDM, and old metal roofing material now instead of cheapie big box store tarps that degrade quickly). I have seen higher PM2.5 levels overall in the summertime when I open the windows, and the average levels are low (3 micrograms/cubic meter)- not much more than what I get in the spring and fall with the windows open (1-2 micrograms/cubic meter). Summary:

• A good quality, tight stove and flue pipe system should make PM2.5 levels a moot point if you are burning wood with the forum recommended moisture content.
• It's possible that a welded steel stove (which doesn't have gaskets and fittings like a soapstone or cast iron stove) performs modestly better in this regard.
• Having said that, dry wood seams to resolve 90% of the issues with PM2.5.
• Ash dust is heavy (compared to smoke particles) and settles mostly quickly and nearer to the stove. I don't worry about breathing this at all, but I hate vacuuming it up (please use a good quality HEPA vac to clean this dust!)

I don't like the VOC levels. I find much higher levels for longer periods of time when I have struggled to get the burn up to temperature after a reload (meaning there one or more not dry enough pieces of wood in the stove). Harder/heavier woods will produce higher VOC levels for longer periods of time (not surprising) and less than optimal moisture content for those harder heavier woods exacerbates the problem. Summary:

• Average VOC level in my house (with no offending sources) is about 75 ppb (AirThings reports anything >250 ppb as good)
• During the active burn phase, levels may rise to 150 ppb or 250 ppb, but then reach 500 ppb for 3 hours or so during coaling (typical)
• I have had some really great burns where the wood was really hard (sugar maple, maybe a piece or two of hickory) and at no point during the active burn or coaling did VOC ever exceed 250 ppb.
• I have had some really bad burns where wood was hard and levels rose to >1000 ppb for 5 or more hours. This is always due to a difficult start and getting stove up to temperature (i.e. wet wood). I suspect that the primary contributor is a lot of creosote coating the firebox, which then gets off-gassed when temperatures drop during the coaling stage.
• In some cases, I've opened windows and flushed the house back to <100 ppb and closed the windows (HRV remains on the whole time) and VOC stays low during rest of coaling (i.e., one of the good burns) and other times VOC bounces back up (one of the bad burns). For reference, the HRV operates at about 0.35 air changes per hour (ACH), and the house is very, very tight (~0.6 ACH50, or nearly non-existent natural air changes without the HRV operating).
• I don't expect 75 ppb during a burn but nor do I expect something like 1000 ppb (which AirThings reports as the middle range of a "fair" rating) for 5 or 6 hours.
• People with leaky houses probably never need to worry about this.

Some things I've done differently with my burns to mitigate high VOC levels:

• Obviously, getting even more anal and religious on burning only very dry wood in which most volatiles are just completely consumed during the active burn and wood. is breaking apart and glowing orange during coaling (i.e. smoldering coals are not good for VOC levels).
• Being less restrictive on my primary air setting (i.e., not going to 0 or 0.5 to slow the burn down). 0.75 seems to work pretty well as the lowest point to get a good even burn throughout the firebox at peak burn.
• Paying a little attention to when I am about 15 minutes from the active burn ending and turning the air up to 1.0 AND opening the pipe damper to fully open so that the load doesn't go into a smoldering coals mode
• If it was a wetter wood, problematic burn, maybe getting air to 1.5 earlier than I would normally set it to 1.0 to just encourage it to burn volatiles before entering cool-down coaling phase.
• Big, squared-off splits at the back of the stove (where air can't reach and burn the wood very well) and a load with one big piece and all other pieces smaller isn't so good. I have started to put a piece of bark or something on the back of the stove before putting a squared-off piece against and this seems to help that back piece burn better with better coaling at the end of the burn. And using more consistent pieces so they are all at an even level of coaling when the active burn is over.
• I really do think one really bad burn just puts so much creosote into the stove that it takes a good burn to get rid of it (some really good burns following a bad burn still have higher than expected VOC emissions, and I think it is burning off the remnant creosote from the inside of the stove).
• I hate having to pay all this attention to this and have a belief that next year will be better for VOCs with even better, more consistently dry wood.

I realize the above is a lot of info. Hope it is helpful to others.

 

[Eman85]

What air purifiers are people using? Never had one but like I said in previous post we seem to be sneezing more than ever before. I know air quality outside isn't good just from the manufacturing and power plants nearby.

 

[cneg34]

I have two Doctors in the family and both would encourage you to take all steps to mitigate. In my case, I am using a mini-split a lot more as it's super efficient. But like anything, it's not the peak values but the air quality over time. Getting outside to cut wood, really isn't a mitigator because the total time you are spending doing this activity is small compared to 24/7 winter heat.

 

[jalmondale]

I have a little Coway air purifier that I'm quite happy with (despite the name, they're a real brand, not an alphabet-soup amazon special). I haven't noticed a huge difference in the winter (I actually got it for summer air quality issues, which it does great with), but I don't see any harm in having it near the stove to clean up after a reload. The various air quality studies that I've read line up with most people's experience in this thread - the only time you'll have an issue is during a reload when the door is open. Making sure you're running a full load and only reloading a few times a day (rather than adding a log every hour or two) is probably the biggest improvement you can make.

 

[Nordicbynature]

I realize the above is a lot of info. Hope it is helpful to others.

Thanks for sharing your comprehensive knowledge.

Do you see these increased values during burns even with the stoves door closed?

I can only reply on the measures of my air purifier, but it shows very low value during burns. Only when I open the door I see increasing values.

I generally have hot and short burns. And then "coast" on the coals with a fan/blower. I don't even try to go for long burns.

Currently my air purifier is not hooked up to home assistant, so I cannot read it out. But I found another older screenshot. It shows how the PM1 spikes after opening the stoves door and goes down to low value quickly, as the air is filtered and ventilated.

 

[Nordicbynature]

What air purifiers are people using? Never had one but like I said in previous post we seem to be sneezing more than ever before. I know air quality outside isn't good just from the manufacturing and power plants nearby.

I would go for a model, which will not trap you into buying expensive replacement filters.

It is a little bit like the consumer PC printer market. You buy a cheap printer and get ripped off on the toner.

 

[John Lehet]

I’m wondering where the VOC is coming from while the stove is burning? Is it coming out during loading, or somehow leaking out of the stove?

My old Jotul just sucked air into the stove from the room. If a gasket was leaking, it pulled air in, didn’t let anything out.

My current Progress Hybrid is a tight welded steel stove in spite of having soapstone inside and outside of the steel. BUT there is a gasketed top plate, under which the pre-catalytic gas might have somewhat of a traffic jam situation before it’s pulled through the cat. Not sure of the fluid dynamics in there while burning. If there’s a flame in the stove I can’t smell anything. If it’s a smoldering catalytic fire I can sometimes smell a bit of a sort of creosote smell around the top of the stove and more rarely in the room. Also a smoldering fire will sometimes do a smolder-smolder-smolder-explode sequence, and that will pop some stuff into the room. So I try to burn with a flame and not smolder it. I’m guessing if I can smell it there are high VOCs, and maybe it’s one flaw in what I consider an otherwise perfect stove. Should get a measurement device…

 

[John Lehet]

Certainly the greatest threat to indoor air quality for me is that I am a home coffee roaster. I roast under a range hood, but still, at the end of a roast there is a fair bit of visible smoke in sunbeams.

I’ve been doing this for years now. I try to do it when my wife is not home, and I also try to evacuate after I do it — go into the other part of the house or go do outdoor chores. The house is leaky enough that it clears pretty well in a half hour. Still, while roasting I’m in smoke.

I know it’s bad. I hadn’t worn one for most of the time I’ve been doing it, but lately I’ve taken to wearing an N95 while roasting.

Air quality aside, home coffee roasting is worth taking up. Though prices for specialty green coffee have doubled in the last 6 months. Prices for roasted coffee of the good stuff have also gone up. I’m amazed that the bin stuff in the grocery store has hardly gone up. Used to be, 12 months ago, great quality green coffee was $6 a pound or so.

I’d hate to see what an air quality monitor would say about it. I’ll die from it, but that’s the way I’ll go out.

 

[Ctwoodtick]

Thanks to everyone for a bunch of helpful responses.
So I did a little test today of extending the chimney with a couple of lengths of duct vent the same size as my 6 inch liner. That brought the height of the chimney up about 4 feet. Previously, I was around 1 foot or so below with the jotul manual wants for minimum. This put me at probably a foot or two above. Maybe a tiny bit more.
I threw in a load of wood and look to see if I could notice any big differences. I feel like the overall burn itself may have been a little bit stronger with secondaries being a tiny bit stronger than usual.
My real focus was on opening the stove door, a couple of different times. Once when the fire was going pretty good, and then another time when most of the flame had died down. I used flashlight to see if I could see any small bits of ash escaping the stove. With the extension in place, I could see no bits of ash escaping to the naked eye. However, when I stood up, I could faintly smell light smoke. I asked my wife for a second opinion and she said she smelt a bit of smoke as well.
To compare, I removed the extension and did the same test with opening the door the same way. I noticed several small bits of ash escaping. This was definitely different than with the extension on. I stood up and smelt the faint smell of smoke or rather the smell when coals burn down. About two minutes later, I asked my wife what she thought and she said she could not smell anything.
Overall, I’m not exactly sure what to think about the test. I’m not sure what I should have been expecting, but I was at least happy to see that there was some visual differences I observed when doing this little test.
I was paying attention to my air purifier, which again doesn’t give specific numbers, but does have a green zone, a yellow zone and a red zone that is visible. During all of the tests, the air purifier never got out of the green zone. Interestingly, it did get into the yellow zone when the door was closed for a good while, but my wife was chopping some garlic. I have no idea if there was any connection with that. But thought it was interesting that there was no change in the air purifier.
I’m definitely reading all the comments carefully, and I am using that info to figure out how to move forward here. Thank you again.
One thing I’m reflecting on is that I have had a habit of opening the door probably more than needed. For a long time I think I’ve been working under the assumption that I’ll start the Fire small with the super seater and then load the stove up perhaps to a medium level. Other times, I’ll time things out so that I can load the stove up right before bed, so trying to do the timing could result in doing a smaller load earlier in the afternoon. I decided last night and early this morning to put in full loads of wood and lit it up with the super cedar. I shouldn’t been surprised, but the wood lit right up with the super seater and it was nice to be able to a good length burn without having to open the door. That’s something I could definitely improve upon in the future as well.
I think I will get myself and additional air purifier that has a PM 2.5 monitor. That way I can better test out where I am currently and with putting that extension back on to compare. I can put my current purifier in the basement where we have a pellet stove.

 

[DBoon]

Do you see these increased values during burns even with the stoves door closed?

My house is very airtight - less than 1.0 ACH50 (almost unheard for most houses). It uses an HRV that operates to exchange roughly 1/3 of the inside air every hour with outside air. I don't (anymore) run a separate HEPA filter (I found it really didn't make much of a difference). This will make my results different from others.

In any case, PM2.5 increases at the beginning of the burn. The rate will stay higher until the coaling stage, then rapidly decrease. How high it goes is really dependent on how wet (or rather, non-ideally dry) and maybe a little based on how dense the wood is. The fact that it drops quickly after coaling even though I am not exchanging house air that quickly means that the stove is emitting PM2.5. This may be because it is a cast iron stove frame with gaskets (I don't know what a steel stove might do - I have no measured basis for comparison).

I can only reply on the measures of my air purifier, but it shows very low value during burns.

Your air purifier measurement is showing something that would make sense to me for a house that had typical air leakage (i.e., not super-air sealed). But this is only a measurement of particulates, and not VOC, and I was surprised that these do not necessarily track together. High VOC for extended periods of time is problematic as well.

 

[DBoon]

I’m wondering where the VOC is coming from while the stove is burning? Is it coming out during loading, or somehow leaking out of the stove?

It's not coming from the reloading because it always peaks right as the active burning is ending and the coaling phase is starting. The door is never opened. It's either coming out of the stove or the stove pipe. I am not blaming the stove - I can correlate this pretty well with a non-ideal moisture content wood load (more moisture = more VOC). Also, (as I did this morning), when I burn a small load for a cold-start (to build a coal bed to then put a full load of wood onto), I will have elevated VOCs (but not crazy bad - maybe 250 to 400 ppb) which I think is due to the active burning phase of the full load burning off some creosote from the inside of the stove. This doesn't tend to go as high or last as long as the elevated levels that being to occur at coaling phase and may last for 5 or so hours.

I’m guessing if I can smell it there are high VOCs, and maybe it’s one flaw in what I consider an otherwise perfect stove. Should get a measurement device…

I cannot smell high VOCs, but I can smell even modest amounts of PM2.5 (e.g., 10 microgams/cubic meter). I can tell if the VOCs are really elevated because I might get a little nasal congestion and maybe some scratchiness in the back of my throat. I would highly recommend an AirThings to measure this because I think some simple changes in drying and burning go a long way to keeping the VOCs low.

 

[DBoon]

Air quality aside, home coffee roasting is worth taking up...I’d hate to see what an air quality monitor would say about it. I’ll die from it, but that’s the way I’ll go out.

Yeah, you'll find a lot of things you don't like. Also, you'll find that VOCs go up with this, but these are not harmful (or at least probably not as harmful as what is coming off of smoldering wood). I've had to learn to recognize the signatures of cooking activities and ignore those from my observations about the wood stove VOCs.

 

[Ctwoodtick]

I’ve got an air purifier coming on Friday that monitors PM 2.5, has Hepa filter and connect to phone. I will run more test to see how I can reduce my exposure as much as possible.

 

[DBoon]

So I did a little test today of extending the chimney with a couple of lengths of duct vent the same size as my 6 inch liner. That brought the height of the chimney up about 4 feet. Previously, I was around 1 foot or so below with the jotul manual wants for minimum. This put me at probably a foot or two above. Maybe a tiny bit more.

I can tell you from experience with a previous stove with a shorter than optimal uninsulated flue pipe that either an insulated pipe or a little bit longer pipe will go a long way to improving the draft, which will give you a better and cleaner burn, overall.

I was paying attention to my air purifier, which again doesn’t give specific numbers, but does have a green zone, a yellow zone and a red zone that is visible. During all of the tests, the air purifier never got out of the green zone. Interestingly, it did get into the yellow zone when the door was closed for a good while, but my wife was chopping some garlic. I have no idea if there was any connection with that. But thought it was interesting that there was no change in the air purifier.

If you can afford to, I would definitely recommend getting something that gives you numbers instead of colored lights. For instance, my AirThings reports numbers, but also puts the date in a Good (green), Fair(yellow) and Poor (red) color when when plotted. "Fair" can be just above good (i.e., 260 ppb) or it could be close to poor (e.g., 1500 ppb). That's a pretty big range and "yellow" by itself tells me nothing. Same with PM2.5.

One thing I’m reflecting on is that I have had a habit of opening the door probably more than needed.

For best indoor air quality, don't treat the stove like a fireplace and load it too often or open the door unnecessarily. Start a burn, let it run the cycle (including burning down coals) and then open it and reload. For me, opening the door is a once every 12 hour or 8 hour process, depending on how cold it is. When I open the door, I might keep it open 5 minutes or so to load, and 10 or so minutes to get the new burn going. Otherwise, it is closed.

 

[Nordicbynature]

Your air purifier measurement is showing something that would make sense to me for a house that had typical air leakage (i.e., not super-air sealed).

Yes, our house is leaky or "self ventilating" as we call it. We like the indoor climate even though it takes more energy to keep us warm. The house handles cold better than wind outside.

Test with similar built houses have shown, that the inside air is exchanged 1.2 times per hour. More in winter, as the temperature differences between inside and outside is higher.

Trying to seal the house would just call for problems like mold. Or it would need a forced / controlled ventilation system and investments that would never pay off.

In Sweden houses where built leaky / self ventilating until the oil crisis in the early 70s. (1973).

For our stove the air is taken from the room. There is no direct outside air connection. I believe it also effects the situation.

 

[Nordicbynature]

I am using a mini-split a lot more as it's super efficient.

Out of economic necessity I always try to run the cheapest way to heat the house. And I do agree with you, a mini-split is super efficient and for us it is often the cheapest way to get the house warm.

Although I make my own firewood, which cost me not more than my working hours, I don't value the wood to be free, as I can always sell the excess firewood. So I always value wood at the price I could sell it for.

Now temperature has gone above freezing with daytime temperatures being at 5° C (41° F) the mini-split is most often the most economic choice.

We have dynamic electricity prices (changing 96 times per day). That generates additional opportunities to run a mini-split at super low costs.