smoke getting into my room

[john81]

Hi, I'm new to wood stoves and installed the flue and wood stove myself. I have a problem with smoke entering my room when opening the stove door for re-fuelling. Let me first describe how my system looks like:

We have a Morsoe 1412 stove in an old house. The masonry chimney is about 5 meters tall and I used a flexible, double wanded stainless steel flue pipe which I put into the masonry chimney. The fireplace has a concrete plate at 1 meter height with a 12 cm hole where a 2 mm thick iron flue pipe is connected to the flexible double wanded flue pipe. I used a 90 degree T piece to convert from vertical to horizontal flue pipe as I use the rear connection of my Morsoe 1412 stove. The reason for using the rear connection is otherwise we have to put the stove inside the mantelpiece which had some wooden parts, so we want to keep the stove at distance from this part. We therefore put the stove about 15 cm in front of the front side of the mantelpiece.

When opening the stove door, over 50% of the time smoke is visibly coming out of the stove, which creates an unpleasant smell in my room. Things I've tried without effort:

* opening the door only when temperature is high enough
* opening the door just a few cm's, waiting a moment and slowly opening it further
* re-fuelling as quick as possible
* crack a window before opening stove door
* waiting for the flames to disappear, loading the new wood onto the glowing coals

I would think draft would be ok as I can hear a constant blowing / airflow from the top (secondary) air intake. But as this is a modern stove which has a baffle which directs the flames to the top front of the stove (door), to me it seems not that strange that smoke is getting into my room when opening the door. My dad has a (different) modern stove as well and he has the same problem of smoke entering the room when opening the stove door.

I'm wondering what could be the cause and solution to this problem? The only thing I can come up with is raising the draft although I doubt that draft is too low. I have a 12 cm diameter flue, total length is about 6 meters. I've read that the horizontal part of the 90 degree T part should not exceed 15 cm length. I measured mine and it measures 40 cm. Would this greatly affect draft? If so, could this be the cause? I've also read (after installing my stove and experiencing the smoke problem) that the top connection of the stove is alway preferable to the read connection as smoke prefers to go up rather than move in horizontal direction.

Maybe I'm completely wrong, or there are other causes? I hope you can help me. If needed I can supply photo's or drawings of my system. I use seasoned, dry firewood. (I didn't measure moisture content)

We don't have any mechanical ventilation system in our home. We have another chimney in our house, which has two separate sides, 1 is covered (not in use), the other is connected to a gas stove.

 

[DAKSY]

Have you tried opening a window before you open the door?
If that mitigates the backdraft, you probably can eliminate
the issue by putting an Outside Air Kit (OAK) on your stove.

 

[MMH]

If your T is double the recommended length, and comes right from the stove (if I’m understanding your description), I’d say start there.

 

[stoveliker]

Is your wood dry? (<20 pct on a freshly split surface)?
Are you reloading on coals (should not smoke at all) or on burning wood?
The temps in NL are not that cold yet, which affects draft as well.
For every foot of horizontal run, you need to add two feet of length on top of the minimum specified length (see manual).
For every 90 degr elbow you need to add a foot of vertical length as well.


So you need to add at least three feet to the minimum specified length here.

 

[kennyp2339]

If you hear air movement check to make sure you have a tight seal on the T going to the stove collar, make sure there are no obstructions if the chimney has a cap w/ screen, whats the diameter of the chimney liner?

 

[EbS-P]

What is your outdoor temperature when you are burning? 5m with a .4 horizontal run to a T makes it more like 3.5-4m effective height. If you can add 1 m of height (even temporary to test its effectiveness). I would start there.

 

[PaulOinMA]

You mentioned opening a few cm and waiting moment.

Try: Just break the latch, but not open, for longer than a moment to let a draft around door start. Then open slowly.

 

[begreen]

It sounds like you have tried several ways to mitigate the problem without success.

Would it be possible as a test, to connect the stove temporarily directly to the tee snout without the long extension? This should not harm the mantel with just one or two fires. If you are worried about that, tack some aluminum foil over the area of the mantel above the stove.

If this fixes the problem or at least makes it much better, then a permanent mantel shield on spacers may be the solution.

 

[Poindexter]

I notice on page 5 of the owners manual the part ID #1 smoke hood must be removed if the stove is going to use the rear outlet, or if the stove is going to be installed on a boat with less than 4.5 meters flue height.

Has the smoke hood been removed from this stove?

 

[john81]

Hi, first of all thanks for the large amount of replies!

@DAKSY: I always crack a window as I think ventilation is always a good thing, especially with wood stoves (particles, fumes)
@stoveliker: I bought the wood as stated dry and it feels dry. I currently don't own a wood moisture content meter but I'm considering to buy one to check progress of drying process. I tried both loading on burning wood (flames) and just glowing coals. Both lead to smoke getting into the room, although when loading on coals only it seems the change of getting smoke in the room is ( a little) reduced.
@kennyp2339: the diameter of the inner liner is 120 millimeters (12 cm)
@EbS-P: outdoor temperatures are around 8 degrees Celcius (46.4 Fahrenheit)
@PaulOinMA: I will try that
@begreen: good idea, this is possible. I will try removing the horizontal part and connect the T part straight to the rear of the stove
@Poindexter: thanks for your good suggestion, but when installing the stove I removed the smoke hood

I made some pictures of the stove and mantlepiece to show you why I put the stove in front of the mandlepiece as clearance from both sides of the stove will be limited to about 15 cm and about 10-15 cm from the top to the mantlepiece. I also assumed radiation being blocked by the mantlepiece when putting the stove inside the mantlepiece, so this was another reason for me to prefer to put the stove in front of the mantlepiece rather than inside it. I wasn't aware of the 15 cm (?) limit of horizontal flue length back then. Even the webshop / seller of the flue pipe has an example picture of a t-part with a 25 cm horizontal pipe...

 

[begreen]

Thanks for the pictures. They help a lot. I can see the concerns about the mantel now. The sides would also be much too close if the stove were directly connected to the tee. Is the connector pipe a proper distance from the mantel? If it is single-wall pipe it should be at least 46cm away from the mantel wood.

If the stove works much better when temporarily connected to the tee as a test, then I would lose the mantel completely or replace it with a non-combustible one. Otherwise, about all that can be done is to raise the liner and tee up so that the connector is pitched uphill toward the chimney at least a centimeter or two.

 

[moresnow]

Nice looking place. Is there any rise in the horizontal connector pipe section as it heads from the stove to the 90? Worth making sure of that to start with.

 

[stoveliker]

And if all that dies not work, adding height on top will increase the pull through the sluggish horizontal section.

 

[wjohn]

Nice looking place. Is there any rise in the horizontal connector pipe section as it heads from the stove to the 90? Worth making sure of that to start with.

My thought too... Easy enough to check with a level.

 

[john81]

Nice looking place. Is there any rise in the horizontal connector pipe section as it heads from the stove to the 90? Worth making sure of that to start with.

Thanks for your reply! It's level. Would draft improve if it's not level, but raising a little towards the 90? (not sure if it is possible to let it raise a little bit because of the connectors on the tube endings.

 

[john81]

Thanks for the pictures. They help a lot. I can see the concerns about the mantel now. The sides would also be much too close if the stove were directly connected to the tee. Is the connector pipe a proper distance from the mantel? If it is single-wall pipe it should be at least 46cm away from the mantel wood.

If the stove works much better when temporarily connected to the tee as a test, then I would lose the mantel completely or replace it with a non-combustible one. Otherwise, about all that can be done is to raise the liner and tee up so that the connector is pitched uphill toward the chimney at least a centimeter or two.

The horiozontal pipe is single walled and distance between mantel (wood) and pipe (outer edge) is 29 cm. I will check temperature of the mantel (wood).

 

[moresnow]

.25" of rise per foot of horizontal run is common here. No guarantee it will drastically improve anything but it sure wouldn't hurt!

 

[begreen]

Thanks for your reply! It's level. Would draft improve if it's not level, but raising a little towards the 90? (not sure if it is possible to let it raise a little bit because of the connectors on the tube endings.

Yes, it should be pitched upward toward the tee a centimeter or two.

 

[john81]

Yes, it should be pitched upward toward the tee a centimeter or two.

Hi, I will try that as well, I hope the endings will fit while applying a small angle.

 

[john81]

Another question: the back of the stove is 12 cm in front of the front of the mantelpiece. According to the Morsoe 1412 manual, a minimum of 60 cm distance / clearance between the side walls of the stove and a flammable object (like my mantlepiece) is adviced.

Would it be ok to move the stove 12 cm closer to the t-part (90 degree bend)? This would be a reduction of about 25% of horizontal tube length and put the back of the stove just in front of the mantlepiece.

 

[begreen]

Would it be ok to move the stove 12 cm closer to the t-part (90 degree bend)? This would be a reduction of about 25% of horizontal tube length and put the back of the stove just in front of the mantlepiece.

That's too close. The stove may be small, but it is highly radiant.
Is the connector single-wall pipe? If so, what does the local code require for its clearance?

 

[velvetfoot]

You mentioned a baffle. Is it in the proper position, as specified by the manual?

 

[john81]

That's too close. The stove may be small, but it is highly radiant.
Is the connector single-wall pipe? If so, what does the local code require for its clearance?

Hi, local code tells that the minimum distance between single wall pipe and flammable objects is 45 cm. I decided to not move it towards the front of the stove.

 

[john81]

You mentioned a baffle. Is it in the proper position, as specified by the manual?

Thanks for your reply. I checked the baffle position, it looks like it's placed as specified by the manual.

 

[john81]

Hi, I worked on the stove this morning: it semed that the horizontal single walled pipe was actually not 100% horizontal, but a little bit descending towards the t-piece (I guess about 2 millimeters for 45 cm pipe length). I shortened the vertical part above the t-piece so right now the horizontal pipe is raising a few millimeters towards the t-piece. Not as much as advised, but the pipe fittings only allow a small angle. I put some extra rope around the back connector of the stove as I suspected some air / smoke leakage here when there was very little draft.

I also called both the wood stove shop and flue shop (two different shops), and the stove shop assured me that the stove would never leak any smoke into my room under normal operation. They told me that my current 45 cm horizontal flue length should be ok. I doubt if this is correct after my research online.

They told me to contact the flue seller which I did, but I have to wait for them to reply. They actually advised me agains a 2x45 degree (= 90 degree) bend piece and suggested me to buy the t-piece as this would be easier for maintanance and more common. They even have a picture on there website as a guidance / example configuration where the horizontal length is 25 cm!

I discovered some play in the single walled flue tubes / connections: when putting them together and sucking on the area where they overlap, I was able to feel air coming through, depending on how much I tried to bend them. Not sure if this has to be 100% air-tight?