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Small Cabin Forum / Useful Links and Resources / Study on Indoor Air Quality While Using Wood Stoves
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rockies
Member
# Posted: 24 Feb 2017 21:24
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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3080954/

Anyone already use HEPA filters?

MtnDon
Member
# Posted: 24 Feb 2017 21:36
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Yes, they have helped with allergies. The air handler that serves the furnace and A/C also uses a high MERV filter that filters smaller particles than the more normal furnace filters.

rockies
Member
# Posted: 24 Feb 2017 21:41
Reply 


DIY version

http://off-grid.info/blog/check-out-this-awesome-diy-low-tech-air-purifier-saves-hund reds-of-dollars/

MtnDon
Member
# Posted: 24 Feb 2017 22:16
Reply 


It is unfair to mention a MERV 11 filter (as used in the link) to any filter that meets the HEPA definition. MERV 11 is a good residential filter; it is rated to filter out particles down to 1.0-3.0 micron Particle Size with 60-65% efficiency. A HEPA rated filter should filter down to 0.30 micron particle size with >99.97% eff. on .30 pm Particles. Even better on the filters used for cleanrooms.

FYI, it is a bad idea to use a filter with a MERV greater than 11 in most furnace air handlers, unless they have been designed for the higher MERV values. That is because the higher MERV has greater resistance to air flow and may overload the blower motor.

MtnDon
Member
# Posted: 24 Feb 2017 22:18
Reply 


I don't doubt the gaffer taped unit filters air, but it is not a replacement for a HEPA filter.

rockies
Member
# Posted: 25 Feb 2017 18:40
Reply 


I think the main issue in regards to using HEPA filters is "have you ever considered the amount of particulates your wood stove is adding to your indoor air"?

The older model wood stoves in particular produce a very high level of "grams/hour" emissions and a lot of it can leach into your cabin (Nobody really thinks about the particles that can hang around for hours inside your cabin).

You may install an outside air vent to the stove itself so that the fire doesn't pull combustion air from inside the room but what do you do to clean the rest of the cabin's interior air?

MtnDon
Member
# Posted: 25 Feb 2017 21:03
Reply 


Use a recirculating type of air filter.

I was mainly being critical of the term HEPA being used for a DIY filter system that was not even close to the HEPA ball park.

paulz
Member
# Posted: 26 Feb 2017 09:00
Reply 


I don't understand. If my stove is pulling in room air and expelling it out the chimney, where are the smoke particles coming from, outside air?

bldginsp
Member
# Posted: 26 Feb 2017 10:45
Reply 


Every time I open the door of my woodstove, no matter how hard I try, a little puff of smoke comes out, or a big one if I'm not careful.

But you raise a good point paulz. Some wood stoves have air ducts to pull in outside air, bypassing the room air. Ultimately this is more energy efficient. But most stoves just pull air from the room, so window and door leakage provide most of the air, which gradually circulates and replaces interior air. Or, you can instal a small duct in the wall or floor to let air in the room for the stove.

I guess the question is how effective this recirculation is at removing particulates from interior air. The study seems to indicate that even very small amounts can have negative health effects.

KinAlberta
Member
# Posted: 26 Feb 2017 12:10 - Edited by: KinAlberta
Reply 


I'm glad this issue is attracting attention!

Between our two cabins (father built one, uncle built the other) we have a couple classic old wood stoves (chrome and all) plus a couple more coal/wood heaters and do they ever smoke. It's horrible in my view.

As an asthmatic I could never understand the hypocritical attitude of militant extremist anti-smokers that made excuses for camp fires. Crappy old classic looking wood stoves, like crappy old collectable cars, just get defended more vigorously.

For me, a weekend at the lake meant several days of wheezing and extra meds. It got so bad that I just don't overnight there anymore. Haven't overnighted more than once in 20+ years.

I'd love to replace them but one, the stoves are keepsakes of sorts and two, joint ownership (My brother and I) makes for basically zero approval to spend a cent on anything. It's why no one should ever jointly own anything - lowest common denominator rules rule.

I bet a lot of households are in the same quandary. The horrible old smokers never die so those that have concerns just can't get buy in from spouses to spend thousands on health-safety.

MtnDon
Member
# Posted: 26 Feb 2017 13:32
Reply 


Too bad when sentimental feelings get in the way of progress and better health for family members. The old wood stoves belong in a museum, not everyday use.

paulz
Member
# Posted: 26 Feb 2017 13:36
Reply 


Quoting: bldginsp
Every time I open the door of my woodstove, no matter how hard I try, a little puff of smoke comes out, or a big one if I'm not careful.


Me too, and I've been meaning to ask about that. I guess it's a normal occurrence. How many face fulls of smoke before I learn not to yank the door open?

The other thing that happens is, after packing the stove for the night, upon opening some still burning chunks have rolled to the front and fall out the door. More smoke.

MtnDon
Member
# Posted: 26 Feb 2017 14:28
Reply 


With a low or smoldering fire, wIt's a VC Aspen. The cen the door on ours slowly we get no smoke in room. But if I yank it open there is a curl of smoke that escapes. With a fire burning strongly the chimney draft overcomes any tendency for smoke to escape the door. It took me a while to train myself to open the door slowly.

With our stove I believe that is because of the burn / smoke path. Smoke is led towards the front of the stove and passes up through an opening into the upper "re-burn" chamber where it travels to the rear of the stove to exit via the chimney. With a low fire the suction from the door being yanked open draws a smoke curl into the room.

rockies
Member
# Posted: 26 Feb 2017 18:39
Reply 


There are some programs that offer incentives or rebates to change out your old smoker for a new wood stove. The best stove I've found so far is the Woodstock Soapstone Ideal Steel Hybrid at 0.5 grams/hour.

http://www.woodstove.com/

Besides wood stoves I was surprised to read about the vast quantity of particles emitted from cooking with propane (or using any type of propane appliance indoors). I plan on having a good quality range hood installed with a make-up air vent and using a direct vent propane wall heater that uses no indoor air.

http://empirezoneheat.com/products/direct-vent-wall-furnaces/

When people think about indoor air quality they usually think about fumes and toxins emitted from paint, carpets or particleboard but never think of cooking sources.

Greenland South
Member
# Posted: 26 Feb 2017 19:51
Reply 


If your wood stove is spilling smoke it's likely one of two things.
1) Your system. Wood stove, flue pipe and chimney are poorly designed.
2) your chimney and flue pipe need to be cleaned.
What it comes down to, if you smell your wood burning, something is wrong.
It doesn't really matter if your stove is new or 30 years old.

rockies
Member
# Posted: 27 Feb 2017 20:01
Reply 


https://www.buildinggreen.com/newsbrief/indoor-air-quality-study-supports-replacing-o lder-woodstoves

rockies
Member
# Posted: 27 Feb 2017 20:16
Reply 


Indoor air quality testing kits.

http://www.modernalchemyair.com/screen-check-home-air-quality-test-kits/

paulz
Member
# Posted: 30 Nov 2018 15:01
Reply 


I've had my stove going for a few days now and my breathing seems a bit more restricted. Looks like an air quality test kit cost just as much as a HEPA filter, about a hundred bucks. Maybe just get the filter?

rockies
Member
# Posted: 30 Nov 2018 19:12 - Edited by: rockies
Reply 


Maybe you're suffering from carbon monoxide poisoning. Do you have a detector? If not, open a window for a while and get one, then have your stove checked. Your stove pipe may be blocked.

paulz
Member
# Posted: 30 Nov 2018 20:33
Reply 


Yeah I thought about that so I checked my CO detector, which is in the same room (this is at my house, in the bedroom). It's working and passes the self test. My wife is fine. I checked the chimney cap, open. I may just be wheezing from hiking yesterday.

DaveBell
Member
# Posted: 1 Dec 2018 10:02 - Edited by: DaveBell
Reply 


That study is crap. It's suggests putting a band-aid on the problem instead of solving the problem.

Greenland South comments are correct but not complete.

1. A study on the major cause of wood stove smoke in the house found poorly designed installations of wood stoves. They measured the smoke inside the house. All the people suffering from smoke inhalation had wood stove smoke coming back into the house - mainly from wind. So why try to filter the inside air - you are still breathing the smoke? Duh.

The standard for chimney pipes exiting the house is two feet above the peak of the roof. That's a minimum.

Smart folks will either buy a stove with an external air point on the stove or drill a hole and make one. If your stove is pulling inside air only, you are pulling cold air and smoke in from around doors, windows, and other house frame boundary leaks. Kinda defeats the heating capability doesn't it? Moreover, it helps pull in the smoke.

So here is a recommended wood stove installation to minimize smoke in the house.


Find the prevailing wind direction. The chimney exit needs to be on the downwind side of the house. Either roof exit or wall exit.

For either exit, the chimney needs to be two feet above the peak of the roof for code. So make it four feet above the peak to help keep the smoke out.

Seal the chimney pipe joints with 3M Hi-Temp metal tape.

Install double chimney pipe from the wood stove to the roof to help keep a good draw during low burn times. If not you risk back-draft in early AM hours.

Buy of make an external air kit. You may have to drill a hole in the front side of the stove. Two inch minimum. Bottom is worse, back is okay (typical from manufacturer), middle side towards front is best. You need a control valve. No PVC until in the wall. Hose clamp metal screen on the outside exit to keep bugs out.

Make sure your stove door seal is not worn out. There may be a recommended replacement interval.

So drawing inside air, upwind chimney pipe exits, and too short chimney pipe will almost guarantee you are breathing your wood stove exhaust.

rockies
Member
# Posted: 1 Dec 2018 18:50
Reply 


Which study? There are several mentioned.

DaveBell
Member
# Posted: 2 Dec 2018 10:47
Reply 


This stove was in an airtight house in the northeast U.S. When the owner used the cook stove exhaust fan, it drew smoke from the wood stove. So they retrofitted an external air intake to the wood stove.
Pike__Wood_stove.jp.jpg
Pike__Wood_stove.jp.jpg


neckless
Member
# Posted: 2 Dec 2018 21:22
Reply 


all is not so simple some times.... my cabin had the chimney a ft below the peak so i did changed it to 2 ft above and it did not work very good at all down drafting all the time smoke in cabin....so the cabin was twenty years old at the time so i thought its work like that for a long time , i had to change it all back weird but the laws of air flow do what they want...lol

Greenland South
Member
# Posted: 3 Dec 2018 11:10
Reply 


In Canada it is NOT required to have a chimney 24" above the peak of the roof. What is required is that it be 36" above the highest point where it exits the roof and 24" higher than any structure or roof within a 10' Radius.
As far as modifying a stove, well that's up to you. However as a WETT Inspector, I would mark a modified stove as non compliant. It's then up to the Authority Having Jurisdiction or your insurance company as to whether they accept the risk.

DaveBell
Member
# Posted: 3 Dec 2018 22:52
Reply 


You wouldn't mark it non-compliant if it was approved first.

Greenland South
Member
# Posted: 4 Dec 2018 08:52 - Edited by: Greenland South
Reply 


Approved by who? A letter from the manufacturer would be the only approval worth anything.

Nate R
Member
# Posted: 4 Dec 2018 10:51
Reply 


This article is a bit silly. They state that there's evidence that some of the indoor air pollutants are from smoke. They don't tell you what fraction, or if there's even a way to tell. They also tell you that the values measured BEFORE filtering the air are well below the EPA "standards."
So, what about areas that don't woodburn? Blaming this on woodburning BECAUSE there is SOME fraction of smoke particle in the air?

I looked for my local area, lots of people wood burning in that region......And even LOWER #s there than this study. EPA "standard" was like 15, this study averaged 11 BEFORE filtering. My area was like 7.

So, of course indoor air filtering can help, but how much is due to local/your own wood burning is tougher to say. (How much was from debris/trash burning? How much was from the same dwelling, and not drifted over from teh neighbor 2 miles away with the OLD smoke maker?)

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