Question about low draft

[madbladder]

I'm having a problem with not enough draft I believe. I have a Lopi Answer woodstove. When I run the woodstove, commonly I can smell smoke in the basement coming through the cleanout, sometimes there is a haze from so much smoke. I have a friend with experience with woodstoves and he says mine is much more difficult to start than his and there is definitely less draft compared to his. Also, sometimes if I don't get the fire going right at the beginning, smoke will billow out of the intake of the stove. I always put a couple of pieces of paper in the flue and light it to preheat the flue, this helps a little.

I have a masonry chimney, flue size inside dimension measures 6 3/4 x 6 3/4 square, flue length is roughly 20' + 6' of pipe going to the wall from the stove.

I bought a 6" stainless liner recently thinking that my flue was too large. Once I actually looked at the flue and saw that it was 6 3/4, now I'm questioning if putting in this liner is going to make any difference.

Is it worth putting in this 6" stainless liner? It should just barely fit according do my measurements? 6" is the recommended size for this woodstove.

Thanks in advance for any thoughts.

 

[begreen]

Welcome, love your handle. There must be an interesting story connected with that.

Is this an exterior chimney? They can be touchy, especially when it's not very cold outside. The flue pipe doesn't sound like the main issue. One thing you might try is sealing the cleanout tightly. If the cleanout door leaks air, it could be affecting draft. As a temporary test, take some wide tape like duct tape and seal it up. If that helps, seal it up with a healthy bead of silicone.

How is the stove connected now? Can you describe the connecting pipe setup? Is there an elbow above the stove? If yes, is there a section of horiz. pipe after the elbow? That needs to be pitched uphill at least 1/4" per foot.

 

[jebatty]

It's possible the 6" flue liner will help. A 6-3/4" square tile flue has 45" sq of cross-section area (almost the same as an 8" diameter flue) and a 6" diameter flue has 28" sq of cross-section area. I would try everything else before moving to the more expensive flue liner solution attempt, because if something else is the cause, then $$$ up in smoke.

 

[ansehnlich1]

I'm going to post this article regarding "stack effect". I didn't understand it until I read it a bazillion times, but numerous homes I've had in the past had woodstoves and fireplaces that never worked right, always throwing smoke into the home. I didn't understand why until I fully understood what this article explains....

(broken link removed to http://www.thechimneysweep.ca/2stackeffect.html)

This may or may not be your problem but my suspicion is that it has something, if not everything, to do with it.

 

[djarseneault]

A 6" liner will be next to impossible to get down your 6 3/4 square flue. All it takes is some extra mortar sticking out at the tile seam, or two tiles not lined up perfectly and next to impossible becomes impossible. I'm sure some will chime in and say they did it or someone they know has done it, but trust me I've installed alot of liners over the past 15 years, and it won't fit.

 

[madbladder]

Welcome, love your handle. There must be an interesting story connected with that.

Is this an exterior chimney? They can be touchy, especially when it's not very cold outside. The flue pipe doesn't sound like the main issue. One thing you might try is sealing the cleanout tightly. If the cleanout door leaks air, it could be affecting draft. As a temporary test, take some wide tape like duct tape and seal it up. If that helps, seal it up with a healthy bead of silicone.

How is the stove connected now? Can you describe the connecting pipe setup? Is there an elbow above the stove? If yes, is there a section of horiz. pipe after the elbow? That needs to be pitched uphill at least 1/4" per foot.

It is an exterior chimney. I have connected the stove with a 3' vertical 6" pipe, then a 90 deg elbow, then connecting into a 21" double insulated pipe that goes into the wall fitting nice and snug into an 8" round masonry flue connection. I never bothered to seal it in, I figure it's best to leave it so I can remove it for cleaning. The 21" horizontal pipe is pitched just over 1/4" per foot.

I'll try putting the tape on the cleanout and see if that helps.

Thanks for all the responses!

 

[Chief Ryan]

I was nervous about my draft because i only have about 10' of flue. The way my house is laid out my stove is at the highest point. I installed an outside air kit because i have a large kitchen hood that use to pull the smoke down the chimney when i use to use the fireplace. With the O.A.K the kitchen hood does nothing to the draft, and the stove has plenty of draft. I have a 6" stainless liner that is insulated with a 1/2 of insulation.

Good Luck

 

[wallis54806]

There has been some good advice so far in this thread, I will try to add to it.
You probably have a combination of problems. I assume this is your first season with the stove. I also had problems in the past with a Lopi Answer. It was an insert connected to a short exterior chimney.
Here is a list of some potential causes, some already covered.

1. Too warm outside to create a good draft.
2. Tight house. Outdoor air connection would help this.
3. Air leaks near the top of the house. Make sure your attic access is sealed well.

Another suggestion: turn off all exhaust fans and clothes dryer until the fire has heated up the chimney. I use to crack the front door if the dryer was running when I started a fire.

 

[madbladder]

There has been some good advice so far in this thread, I will try to add to it.
You probably have a combination of problems. I assume this is your first season with the stove. I also had problems in the past with a Lopi Answer. It was an insert connected to a short exterior chimney.
Here is a list of some potential causes, some already covered.

1. Too warm outside to create a good draft.
2. Tight house. Outdoor air connection would help this.
3. Air leaks near the top of the house. Make sure your attic access is sealed well.

Another suggestion: turn off all exhaust fans and clothes dryer until the fire has heated up the chimney. I use to crack the front door if the dryer was running when I started a fire.

This is actually my third season with this stove, I've dealt with this problem over the last years. I've been living with it, but my friend insists I need more draft. I built my 1600 sq foot Cape house myself four years ago doing most of the work myself. I have 2x6 walls, everything is overinsulated and wrapped tight. My attic access is a 24x 30" opening with a piece of plywood at the top of the stairs, with overlapping r30 insulation criss crossed to seal it tight. I have tried opening a window or door to see if that helps the draft in the past, it doesn't seem to make it any easier to start a fire.

Should my stove be as easy to start as my friend with an insert that has a 6" stainless flue liner with an insulated blanket?
I have no trouble starting his fire. He was unsuccessful in starting mine.

Even when a fire is roaring, there doesn't appear to be near as much draft that I can feel with the door cracked open as I would expect would be normal.

One last note, this stove is an older one that I bought used that was manufactured in 1984. I'm just adding that info in case it makes any difference.

Thanks everyone for your help!

 

[begreen]

Have you tried opening a window a couple inches, close by the stove? Also, when testing using the open window, be sure that no fans (bath, whole house, ventilator, clothes dryer, kitchen, etc.) are running. If that makes an appreciable difference you may be wanting to consider getting a more modern stove that can accommodate an outside air kit.

If that makes no difference, then looks closely at the flue cap to be sure it's not clogged. Draft may also be improved by redoing the connector pipe with a 45 on the stove, then diagonal pipe, then another 45 at the chimney connection.

 

[madbladder]

Have you tried opening a window a couple inches, close by the stove? Also, when testing using the open window, be sure that no fans (bath, whole house, ventilator, clothes dryer, kitchen, etc.) are running. If that makes an appreciable difference you may be wanting to consider getting a more modern stove that can accommodate an outside air kit.

If that makes no difference, then looks closely at the flue cap to be sure it's not clogged. Draft may also be improved by redoing the connector pipe with a 45 on the stove, then diagonal pipe, then another 45 at the chimney connection.

I have a window about 8 feet from the stove that I have tried opening and it does not seem to make a huge difference in getting a fire going, no fans are running when I do this test. This is a test I've done during the winter when it's colder outside, it is too warm outside right now to do a test right now.

I don't believe a 45 would work in this situation without installing a fireproof wall behind it. The stove is 16" from the drywall in the back, which is the recommended distance minimum.

Is it possible that the flue cap I have installed could effect the draft? It is a big one covering 2 flues and is roughly 8 inches in height if I remember correctly.

I'm still considering the stainless liner. Today I went on top of the chimney and put the T down the furnace flue (because it's cleaner) with a wire and it easily went down five feet with no trouble. I think I can get the whole liner down without too much trouble if I clean the woodstove flue really well. I'm going to try everyones suggestions first though. I got a great deal on the liner several weeks ago. The Stainless liner kit was $315 for a 25' kit with T and Cap. I guess I jumped the gun a little buying this liner, oh well.

Thanks for all the replies!

 

[begreen]

If you use double wall fittings and pipe the clearance will be ok. Using double wall will also help the draft by keeping the flue gases hotter.

By the description the flue cap doesn't have a screen, so that is not the issue. Have you considered putting an extension on that flue?

 

[madbladder]

If you use double wall fittings and pipe the clearance will be ok. Using double wall will also help the draft by keeping the flue gases hotter.

By the description the flue cap doesn't have a screen, so that is not the issue. Have you considered putting an extension on that flue?

The cap is rectangular and has 1" openings around all sides to keep the squirels and birds out, there is no mesh screen.

How tall would the extension be? The flue is 2' over the peak of the roof.

 

[begreen]

We cross posted. There are too many moving options on the table. First, try sealing the cleanout. Test. Then, considering you have the liner, that's worth a shot. If it were me I'd also switch out the interior single-wall to double-wall pipe with the 2-45s as previously described. That could be all that's needed to improve the draft. If so, rest and enjoy.

 

[branchburner]

I'm going to post this article regarding "stack effect". I didn't understand it until I read it a bazillion times, but numerous homes I've had in the past had woodstoves and fireplaces that never worked right, always throwing smoke into the home. I didn't understand why until I fully understood what this article explains....

(broken link removed to http://www.thechimneysweep.ca/2stackeffect.html)

This may or may not be your problem but my suspicion is that it has something, if not everything, to do with it.

This is a great link, one of the best articles on stack effect I've seen. I'm guessing the older stoves may not have an outside air kit, but I would think with a super-tight house it would really help with draft.
On the other hand, if that cleanout is leaking air big time, fixing that might be enough. Quick and easy, too - good luck!

 

[woodconvert]

author="BeGreen" date="1223720124"]

Is this an exterior chimney? They can be touchy, especially when it's not very cold outside. The flue pipe doesn't sound like the main issue. One thing you might try is sealing the cleanout tightly. If the cleanout door leaks air, it could be affecting draft. As a temporary test, take some wide tape like duct tape and seal it up.

As the proud owner of an exterior masonry chimbly....my first guess would be a leaky cleanout door. Having dealt with that myself it makes a world of difference if it's NOT sealed. As BG says, seal it somehow THEN go to plans B,C and D.

 

[woodconvert]

One last note, this stove is an older one that I bought used that was manufactured in 1984. I'm just adding that info in case it makes any difference.

I remember 1984 like it was yesterday and I aint one of the geezers here (yet) but for what it's worth, heat rose back in 84' in a similar manner as it does today ;-P

 

[cousinles]

I think I have the same stove as you, mine was built in 86 and I have no trouble with draft. I have about 6' of single wall stove pipe and 9' of double wall SS chimney. It even drafts good on the warmer days and I don’t have an outside air kit.

 

[madbladder]

That looks just like mine, only I don't have the blower or the brass door. Nice stove!