Have a huge problem....

[ClassicSWC]

Hello everyone, been reading the forum for a while and have a problem.

Last night I tried to start a fire in my Nashua stove. The stove was cold. I couldn't get the fire to start, to the point that the house filled with smoke. Paper wouldn't even burn unless the door was open. This is the second time this has happened, both times it occured at night when the stove had been cold all day. (Yes the damper was open)

The specs for my setup are: A Nashua stove with 6" pipe, a 45 elbow at the base of the stove, 4' straight up with a damper in the middle. A 45 elbow going out thru a reducer/expander, going thru the block, into 8" ss double wall all fuel pipe, which runs up the side of the house (single story rancher) thru the soffit about 4'.

I'm assuming this a draft problem. I was even using a hand held torch to try to get it to lite, to no avail.
How can I fix this? Any suggestions?

Thanks, Spencer

 

[webbie]

You will find a lot of info in the QA and in the articles section about chimney reversal.......

It might more accurately be called a startup problem than a draft problem. Chimneys which may function well when warmed up can still be hard to start.

start with
https://www.hearth.com/econtent/index.php/articles/chimneys_an_unexact_science/

Check out some of the articles on starting a fire - also search the forums and site for reversing chimney, etc.....

In some situations, I have found that installing a TEE on the stove pipe near to the chimney can help - you can open up this TEE, stuff a ball of newspaper in it, light it and it will get sucked up the chimney - then light the stove and all should be fine. Never try to light the stove until you are 100% sure the chimney is drafting upward.

 

[Danno77]

I don't know if I'm stupid or crazy (like a fox, of course), but last year I had this problem and I think I might even have mentioned this solution on someone else's thread as a possibility before I tried it, but it did work.

You know the chimney is cool, so DO NOT load the stove yet. Take a small electric space heater and leave it inside the stove running with the door shut (air open) or cracked. Wait quite a while. I think I tried after 30 minutes, ymmv.

Then load the stove up, light some paper to ensure the draft, then light up wood as normal. I'd rather shiver for thirty minutes waiting to warm the chimney, then smoke up the whole joint.

 

[Agent]

With my basement install when I get that occasional reversal (you only seem to notice them AFTER you try to light the darn thing) simply throwing open a nearby window or door somehow restores the draft.

 

[Redbear86]

i wonder how many people here have tried this electric draw collar? pre-heats the flue

 

[pen]

I can usually tell when this will happen because I'll feel cold air moving when I open the stove door. I've had luck starting up my propane torch and propping it up in the stove and letting it run for a while first.

Mike from ESW recommended just setting a hair dryer running on the cold stove (nothing burning inside) and letting it heat up the outside of the pipe. I'd imagine this would only work for single wall pipe.

pen

 

[Jotulover]

i wonder how many people here have tried this electric draw collar? pre-heats the flue

Works great! No more worries :}

 

[Danno77]

I don't know if I'm stupid or crazy (like a fox, of course), but last year I had this problem and I think I might even have mentioned this solution on someone else's thread as a possibility before I tried it, but it did work.

You know the chimney is cool, so DO NOT load the stove yet. Take a small electric space heater and leave it inside the stove running with the door shut (air open) or cracked. Wait quite a while. I think I tried after 30 minutes, ymmv.

Then load the stove up, light some paper to ensure the draft, then light up wood as normal. I'd rather shiver for thirty minutes waiting to warm the chimney, then smoke up the whole joint.

Tried this again and it worked great. One tip, though. Empty the stove of ashes. It's actually pretty impressive how warm the stove and pipe get doing this. All it takes is a simple 1500 wat fan heater. I think they run about 15 bucks for the cheapest non-thermostat controlled one at the local Walmart. You don't want the thermostat to be kicking it on and off anyway, because a stove is such a small space it would shut off in about 10 seconds!

 

[BrotherBart]

Shooting a hair dryer into the flue will do the same thing.

 

[ClassicSWC]

Thanks for the replies. I actually had to take the bottom of the chimney off and burn newspaper in there to get the draft going.

Not sure if this is related or not, but when I start a fire or fire up a new load of wood, the stove "put-put-puts" to beat all and the flame looks like a strobe light. Sometimes it gets pretty loud. Anything to worry about or try to fix?

 

[begreen]

That is puffback and an indication of inadequate draft. This concerns me. You don't want draft reversing late in the burn. How tall is the outside class A pipe?

 

[mdocod]

Go look at your chimney cap. Use a pair of binoculars to get a close look at it. Stand on a nearby hill of available to see it from the side if possible, or just go up on the roof if that is an option for you.... Can you see through the screen? Or is it plugged over?

 

[ClassicSWC]

I have approx 13' of chimney. I made a mistake in my original post, I have two 90 degree bends, not 45's. The chimney cap is fine, I cleaned everything a month ago.

 

[begreen]

That's too bad, the 45's would help here. The problem is a much too short flue. There are 3 - 90 degree turns in the smoke path which have reduced the effective flue length by 7-8ft. The stove is ineffectively running on a 5-6ft flue. It can't establish adequate draft. Add another 3-4ft of pipe and the stove should start to behave much better. The pipe will need a roof brace at 5 ft above where it passes the roof edge.

 

[mdocod]

Hi firestarter,

All it takes is a few fires burned too cool in a stiff cold crosswind to plug up a chimney cap. It can happen in a couple days if conditions are right. I understand you cleaned it a month ago- I still think you should check it.

That said... If I understand correctly.. You have a 6" stove pipe adapted up to an 8" flu, 13' of 8" double wall non-insulated flu correct? Based on my understanding of exhaust systems on engines, a pipe that becomes larger further down stream will often produce more back pressure. The idea is that, as the exhaust enters the larger pipe area, it slows down, cools off, and becomes denser and harder to push along it's way. In the case of a vertical pipe convection draft, I would personally expect the larger pipe section to act as an opportune area for flu gases to slow down and cool off more, reducing draft effort or even efforting to reverse draft effort on cold starts.

I would want 6" flu pipe on a stove with a 6" fitting personally. And in all cases of single story homes, 3-6' of insulated extension should be standard practice IMO but rarely is the case. I've seen/experienced/heard-about poor drafting characteristics in many single story home chimneys.

Eric

 

[begreen]

Yup, good point. Switching to 8" here is adding insult to injury.

 

[ClassicSWC]

Would I be better off puttind the adapter on the stove and using 8" single wall pipe inside? The 8" ss chimney is only 3-4yrs old and I'm not in a position to replace it.

 

[ClassicSWC]

Climed on the roof and everything was fine, no buildup anywhere. I plan on adding another section and a roof brace to the chimney. Would going to 8" inside help out as well? Thanks.

 

[oldspark]

No on the 8 inch, stick with what the Nashua has on it, bigger is not better in this case.