Wood Stove Heat and Chinook Backdraft Problems?

[Cyprs]

Questions for other wood heaters who live near chinooks off mountains.

I live in area where we get tail end of chinooks off Rockies to west of me.

I heat my home with wood heat, Osburn 1600 EPA certified, I have plenty chimney, well over 2 feet higher than any point ten feet away on roof, within code.

I am told the reason my chimney backdrafts in chinooks is low pressure systems that accompany chinooks, when wind blows hard or light the low air pressure forces air down chimney creating a negative pressure house thus smoke in house, carbon monoxide detector goes off. At this point, windows open up, all coals put in large heavy pail and removed outside.

If weather is cold and no matter what the wind speed I then never have a problem with this stove, only in chinooks. People I know who live farther east of me beyond chinooks have no backdraft problems.

I am considering buying a special designed chimney cap that apparently will stop this negative pressure, it was developed in Oregon to my understanding.

Two questions?

1) Do these anti chinook chimney caps work in stopping this problem? If so, which ones work best?

2) Can anyone explain to me exactly why chinooks cause this backdrafting problem if my understanding above is wrong?

Thanks
Cyprs

 

[Shannow]

No comparible experience...but.

I live in a fibro-cement house, with 3x2timber structure.

During storm season (usually hot nights) we have windows open, but have to ensure that we've got the right windows open.

If we get a Northerly, and there are too many north windows open, the whole house groans as it "parachutes". Too many south windows open, and it sucks in (much less noise).

My guess (and it's simply that) is that your wind velocities are sufficient to cause a depression on the downstream face of the building that draws air through a vent, drawing air back down the chimney.

Just a guess

 

[oilyriser]

Also you probably build a smaller fire when the wind is warmer, so there's less draft.

 

[Al]

When the wind came in a specific direction for me the wind somehow reacted with my roof and caused a backdraft even though the roof was lower. I put a brick at each corner of the chimney and put a piece of slate over top so that the there was a 4 inch slit all around. Problem solved.

 

[Cyprs]

Thanks all so far, We have saying in Saskatchewan, "dont like weather, wait a couple hours."

This problem I have will only happen in Chinook conditions, if the temps are 5 degrees or lower below freezing in non chinook conditions the wind can blow any direction 50 mph and not effect the the chimney draw.

January/February is chinook months, this is when that low pressure exists as it is explained to me. People living in northernwestern U.S. near rockies or Canada west will know this weather flow situation.

We can have -40F in January with a 35 mph wind, no backdraft stove problem, 3 days later the chinook can blow in and it can be +40F with the same direction wind speed and we cant use the stove due to low pressure backdrafting. In November we can have the same +40 degree weather with 35 mph wind and no backdraft problem because there is no low pressure system as a January/Feb chinook. Weird huh?.

Al, Our chimney cap sounds much like your idea , some people actually tell me to remove the chimney cap, I see this as worse idea in stopping this backdraft, your idea makes more sense to me, you may have made a homemade design like that fella in the northwest U.S. to combat this backdraft problem.

Oilyriser, your fortunate in the east, you dont get chinooks, on eastern side of Sask. no one has this problem there either, chinooks cant get that far except this strange warm winter only this year, unusal year this one. If I dont get super hot stove then the low pressure air can backdraft easier, the hotter I burn the more heat tries to rise to combat that low pressure or what ever it is in chinook condition, drive one nuts. Most times in normal conditions I just light a little extra white newspaper to pre warm the flue and get draw going little faster, only on extreme calm days do I do this.

Schmoe, is that flue vent installed on top of chimney like a cone to deflect that downward wind effect of some low pressure winds? Is that vent from Oregon area?

Anyone living in chinook area will know what I am speaking of here, all fireplace/woodstove sales techs tell me this, "dont light your stove when there is a chinook." except one, on outlet tells me some fella in Northwest U.S. designed a chinook beater cap, then a second fella designed another. I really dont know if they work, they are around $200.00 Canadian, I am told they look space aged in design to stop downward air pressure yet allow heat/smoke to rise. Possible this is what Schmoe is using successfully?

Anyone out there try one of these special chimney caps in Northwest U.S. or Western Canada?

Is it low pressure associated with chinook causing this backdraft, this only happens in chinooks, any other explaination that low pressure? (most our cold weather comes from high pressure systems, no problems then)

This is a dangerous weather flow, endangers my family, we do use carbon monoxide detector and deal immediately. Last year we had no chinooks, cold winter, not one problem, this year is nuts, too warm, something wrong in the climate/mother nature.

In thanks ahead, here is a tip for anyone woodstoving and wanting a faster more efficient method to light a stove.

When lighting a wood stove/fireplace, put your larger flat wood on bottom of firebox, (be sure not to block air intake in firebox if is located low. Then work up from there with larger to smaller kindling, smallest kindling on top. Now, put paper on top of kindling at very top. Light the paper on top with choke on unit as you would normally do. The fire will burn DOWN, it will immediately ignite a solid coal base on your larger wood on bottom of fire box, kindling is now a coal base on top of combustable wood which keeps burning down and establishing more fire base faster. This system is better than kindling sitting on firebrick/metal on the bottom and continuously needing more kindling to sustain a firebase as is case on the old reverse standard way. You can add larger wood once fire is fully established on large wood base in much less time as standard technique. This greatly speeds up firebox heating which causes less soot, less smoldering and speeds up your time.

One other way I do, put flat board on bottom, then two larger pieces on each side, place smaller kindling on top flat board and between two larger pieces, paper on top kindling again, light. The bottom, sides of larger pieces ignite, then add more wood in middle when fire fully established, very quick and effective.

The old standard small kindling on bottom doesn't establish a coal base, it is tedius/time consuming to keep adding kindling to get that coal base. Either of my systems above is twice as fast and efficent in less kindling and faster heat gain in reducing soot, less smoldering cold and better for the enviroment. Will allow you to get to that comfortable chair with your favorite beverage and enjoy that fire a lot quicker.

When these systems are done right, I can fully load my stove in minutes and walk away and enjoy the fire until the stove heats/ fire establishes enough to choke it down, I dont have to babysit the fire getting it established this way, just choke down after it establishes.

Did you know (according to what I am told) a dying dead rotting tree gives off more harmful emmisions than an efficient EPA approved 4 gram/hour smoke wood burning stove like mine. One cant hardly smeel my wood stove outside in normal operation, my stove is ten years old, I am not hearing numbers like 2.5 grams smoke per hour on newer EPA certified stoves.

thanks,
Cyprs

 

[jmacmaster]

We live 15 mi. east of Helena, Montana, and also get the chinooks (aren't they nice when its been
-20 to -40 below and all of a sudden a chinook hits?). We have an old wood cookstove in the house and an airtight woodstove in the garage. Both buildings are one story and the chimneys are only about 3 ft. higher than the peak of the roof, so the chimneys are fairly short. We've never had your problem. At times, chinook or not, the stoves won't draft quite as well and we have to open the damper more to create more of a draft up the pipe, or smoke comes out of the stove. Have your tried that -- opening the damper more? What happens is that there's more downward pressure in the air than normal and it forces the smoke back down the chimney, so you have to create more upward draft by opening the damper more. In our case, for each stove, I'm talking about a damper that's in the stovepipe right above the stove.

 

[Schmoe]

Believe it or not, I use a fireplace "down" here sometimes and have the same problem but only when the winds shifted, sounds a lot like your problem. Anyway, I installed one of those direction flue vents. It basically turns with the wind and creates a better updraft. Works fine and problem solved.

 

[Audi Junkie]

I toiled with backdraft for a few years. The only thing that solved it was to go up about 5 feet over the peak of the house. imo, there is a "bubble" of high-pressure air that flows around the surface of the house and the only way to beat that pressure pushing back down the chimney was to poke throught it. We are 100% fine now with 40+mph winds, before was bad at 20. 2 feet above roofline is not enough.

 

[Cyprs]

yeah, I leave the damper wide open, I also completely open the bottom choke to get maximum air intake during chinooks. I have stove vented directly to outside to burn outside air directly.

I called a fireplace outlet, he reinforced what you say jmacmaster, this chinook causes a downward air pressure.

Over the phone I ordered a special chimney cap called "Dikapt", $180.00 Canadian, comes with numerous straps for different circumferences of chimney flue, being designed in Northwest U.S. they should be available for you there if you want the peace of mind in safety too. I will still keep carbon monoxide detectors on, this allows me to keep house warm in chinook conditions without hastle.

On your chimneys, the residential stardards up here is to be 2 feet higher than any point 10 feet away to be to code & for proper draft, I think that is pretty universal.

thanks jmacmaster, will let you know in this topic in future if cap works as good as all the rants and raves this cap is getting todate up here. They have been sold for years up here and he said they have a 100% success rate, not one returned or unsatifactory. Good design and product, stainless steel too as he told me.

Did you try the stove lighting tip I gave in last post?

thanks,
Cyprs

 

[mechtech]

It seems to me that low outside pressure would help, not hurt, a backflow situation.

 

[Cyprs]

mechtech, you have to experience this low pressure on woodstove to really realize the frustration and danger in carbonmonoxide it creates during a chinook. I grew up on eastern side of my Province, never knew what a chinook was then, no problems there with backdrafting on lows, now I am 300 miles west of there and get tail ends of chinook off Rockies about 250 miles further west from here, warm but deadly on heat sourses in homes.

Your right jmac, I load up that stove full immediately after my lighting system quickly combusts fully and burns with choke & damper wide open, then sit down, enjoy the flame to heat up stove to about 250 degrees asap before choking it down, reduces soot buildup. Your fast combustion is helping out with the low soot levels in your stove too. Little like an engine, faster it can heat the cleaner it will run.

Cyprs

 

[jmacmaster]

"Did you try the stove lighting tip I gave in last post?"

No. Since I started using woodstoves in the mid
70's I've always had good luck with tightly crumpled newspaper on the bottom, torn up small pieces of cardboard or food boxes on top of that, small kindling on top of that, small firewood on top of that. Then I light the newspaper. When the fire gets going I add medium sized pieces of firewood and then large pieces after that. After I light the newspaper that's at the bottom, each layer ignites the layer above it.

I always open all drafts and dampers all the way when I start a fire, to help it get going fast, and leave them open for at least 10 minutes so that the extremely hot air goes right up the chimney and prevents creosote buildup by burning any soot that's forming in the chimney. This works real well. My airtight garage stove has a stainless steel double wall insullated chimney pipe, has been in use since 1995, and I have not yet had to clean the chimney. I check it once a year and there's been no buildup.

 

[H2GURU]

You probably need a chimney liner (stainless only!), if your chimney is too fat it cools too quickly,and the burnt gases "fall-drift" back into the house. I had this problem and the liner solved it. Running the stove wide open also works , but you'll overheat and use too much fuel!

 

[Cyprs]

Problem now fixed with a Dikapt chimney cap designed to fight these low pressure problems. It looks like a old style milk steel bottle up side down. Cool design, there is a 5 inch high & 6 inch wide flue on top, then bellies out inside about a 1.5 feet in diameter and tapers again at bottom to fit inside chimney, straps screw to side of chimney to hold in place, good design. Inside is two low pressure fighters in coned tops, first top is smaller which deflects first burst of low pressure wind onto the next lower double sized cone. both cones will not allow any rain or snow or low pressure wind down flue. The cones also allow normal wind to cause draw but dampens it some.

Another benifit, I no longer need the damper on stove pipe, this special cap actually now cuts my excessive high draw on normal high pressure days, this cap makes my stove burn at perfect draw, flame and temp no matter the wind, pressure etc. It absolutely equalizes the stove performance no matter what the eviroment can throw at it, long hot blue flame burn, efficent and equal at all times, wind can blow at night and calm in morning, burns the same now . It was designed in N.W. U.S. Great product, seller told me it has solved hundreds of low pressure problems throughout this area, people all find the equal burn rates as I do too, no complaints to date, I have none.

Cyprs

 

[Gary Allan]

Why wouldn't/couldn't you feed the stove from the same low pressure source (outside)?? Assuming that you can get a damper that isn't part of the door, that is. That would eliminate any backdraft and would eliminate any interior (heated) air from leaving the house.

I mean ..you have your problem solved ..but why wouldn't this work??

 

[Cyprs]

Actually Gary, I have my woodstove vented directly to the outside, I run a 4 inch metal vent pipe from outside right to air intake inside stove pedestal, this is code for any install on woodstove up here. Only outside air burns in this stove, this keep the air quality in house first rate.

This low pressure forcing a 35 to 60 mph hour wind down a chimney is too strong a force for heat to rise or any high or low pressure in house to overpower.

My chimney exceeds being two feet higher than any point ten feet away,this is also code. And creates draft, I am a bricklayer by trade, although I now do mostly acrylic stucco.

For insurance purpose I have UL approval on my complete wood stove install, I sent blueprint/pictures of all clearances, chimney, air venting etc to UL, a UL engineer gave it the UL certification to insurance company. This is a whole new topic, many people are misrepresented by insurance brokers on wood heat systems and learn hard way on fire claims when the fire inspector, not broker does the report. This
UL certification ensures absolute insurance if anything bad happened, *** forbid, protects me and insurance company, win/win.There is nothing in my stove or install causing this backdraft other than low pressure associated with wind in chinook conditions.

You have to experience a chinook to appreciate it, temps can change from -40F to +40F over night. I lived in Uranium City, 30 miles south of NWT in the 70s,young then, one morning I got on the DC3 in -50F, flew on sports trip down to Edmonton Alberta, about 500 miles south and 350 miles north of where I live now, the temp in Edmonton was + 45F, first time I ever heard of chinook let alone experience one. That was a 95 F temp change, I had muscrat, moose hide and duffle lined mitts, moose hide double soled mocassins, wolf fur and duffle insert slippers, large parka with wolf fur lining around hood,getting off plane when people in Edmonton were in fall jackets in this chinook was a little out of place.

I lived 250 miles west of here too on eastern
side of my Province before moving up north, never knew about chinooks, no friends 250 miles west of me burning stoves have this low pressure problem, they cant understand this flow of air here
either, have to experience it to get it I guess.

Many people in my area play a dangerous game, or not understand the silent killer of carbon monoxide. Many foolishly refuse to install carbon monoxide detectors and burn wood, they suffer headaches, watery eyes or disorientation, some foolishly dismiss it as flu or bad night sleep. They will say they have no chimney problems, this is ignorance and are lucky to be alive, especially their children. Every time this low pressure system came in after lighting our stove in good high pressure, our detector goes off, open all windows, remove all coals out of stove, air out house completely. Paint thinner will set this detector off, they are sensitive units.

Prior to this "DICKAPT" cap, there was no remedy except "dont burn the stove in chinook". and hope it doesn't chinook after lighting the stove in high pressure conditions.

I prefer constant cold weather as on east and north side of Province, I like consistancy there, always cold. Wife grew up in this area and I endure the weather for her sake. For example, my weather forcast says -10 tonight, it can go as low as -45 here in January at times. It may get -10 tonight, may not, it may go up to bit over freezing if a chinook comes in over night, Start car at 8am. I have to now go out and set timer on my heat pad and block heater , what would you set it at?

Anywhere else I lived prior to here I would plug in 4 hours, no problem because the temp would be -10 within a degree, not here.

Our weather dropped below freezing and above 3 times through out day today. Kid played on skateboard ramp for an hour in short sleeves, next hour a parka as it snowed lightly. We have no snow on ground, grass actually green, never went dormant due to chinooks and warm flows, last year this time it was -35F with lots snow, go figure.

favorite saying in this area: "dont like the weather in S.W. Sask, wait an hour and it will change"

Cyprs

 

[Gary Allan]

Yes, this is obviously alien to me.

 

[Schmoe]

Nahhhh, I think you guys ripped that off from us here in Oklahoma. The saying here goes..."if you don't like the weather, wait a minute, it will change." What I was talking about is almost like a half wind sock that swivels with the wind. Almost like a windflow direction vane, except the vane is angled at the top to move smoke away from the flue and actually helps pull smoke out of the chimney. Anyway, with the wife and 2 year old having allergies and asthma, I'm about ready to go buy a propane tank and 100% burn ceramic logs. Just ain't worth the problems and finding wood to cut that burns good, i.e. hard wood, is almost akin to finding a needle in the proverbial haystack.

 

[Cyprs]

Cool Idea, a funnel that moves with wind to create an upward draw on a flue.

Cyprs