Stovax Stockton 5 smoking when reloading

[Sir Logsalot]

Hi All,

Having recently had a Stovax Stockton 5 fitted, we cannot seem to avoid the issue of smoke making its way into the room during reloading.

We are lighting it using a top down method with plenty of kiln dried softwood kindling and graduated oak splits with the largest being at the base. Everything starts great with very little smoke; the flue seems to draw well and everything gets up to temp nicely (flue at 230 to 250c) . We are burning air dried oak which is consistently testing at 19% MC on the face of a fresh split.

Having looked through this forum smoking when reloading does not seem to be an uncommon issue (perhaps due to eco stove design/baffle?) but we've tried the usual advice of opening a window in the room a crack and opening the air controls fully before reloading and opening stove door a crack (then slowly after a minute or so) but the smoke smell persists every time we open the door.

We have followed the manufacturers instructions of opening the airwash and secondary controls fully and waiting to the fire to burn down to embers but once the last of the flames has died, part of a spilt will often reignite as soon as the door is cracked, leading to us constantly waiting for the fire to burn out, at which point the flue temp is far lower (around 125c) which I'm thinking won't help the draw much. Another issue seems to be the inconsistency of how well the wood burns; ie when putting a new log/s on the embers the bottom of the log burns well but the top remains partially unburnt unless it's turned over midway, leading to smoke again when opening the door to turn it.

So far I've concluded that we'll either need to start reloading whilst the fire/flue is still hot and has better draw or keep experimenting with log positioning in the stove to ensure more even burn/airflow. I have already been mixing in softwood with the oak and this seems to help somewhat perhaps we should start adding kindling on top of the logs when reloading to assist with an even top and bottom burn?

Anyway, I'll leave it there and hope someone can help their insight/experience on how/whether this can be resolved?

Cheers.

 

[EatenByLimestone]

Try letting the coals burn down further before you reload. Once every thing is burnt to coals, there isn't any smoke that can escape.

 

[Sir Logsalot]

Try letting the coals burn down further before you reload. Once every thing is burnt to coals, there isn't any smoke that can escape.

Thanks; this does seem to make things better regarding the smoking but the difficulty I'm facing is the inconsistent burn of the leftover coals. When I crack open the door they often reignite and will smoke if i open the door fully to reload, leading to an extra couple of cycles of cracking the door open and closing again to get everything completely burned, by which point much of the heat from the fire and the flue is gone. Enough heat remains to catch new logs but these burn inconsistently (from the bottom up) with the tops being only partly charred unless turned (resulting in more smoke).

I'm using the controls correctly as far as I'm aware; after starting I close the primary after around 10 mins and throttle the secondary to around 15%, then using the airwash to control the fire. It's normally set at the centre (optimum burn). When reloading I open the airwash and secondary well before opening the door.

All wood is below 20% dry MC.

 

[EatenByLimestone]

If all of the volatilesare burnt down, there shouldn't be a reignite. Is there a baffle board on top that has slipped forward? This can cause extra smoke to leave the stove.

 

[Sir Logsalot]

If all of the volatilesare burnt down, there shouldn't be a reignite. Is there a baffle board on top that has slipped forward? This can cause extra smoke to leave the stove.

Hi, there is a baffle at the top and as far as I can tell it's correctly located, though I was surprised to see how narrow and far to the front the slot for the smoke/air to enter the flue was; effectively the smoke/hot air from the fire is rising then moving forwards before its pulled up the flue; once the door is opened I can't really see how this design still works effectively to draw the smoke properly as by that point the smoke is almost out of the door so to speak.....if there was no baffle I imagine that the gases from the fire would just exit straight up the flue, although this would affect the eco design...I also wondered if my waiting for the coals to be fully burnt results in the flue losing sufficient temperature to affect the draw so that the gases are not pulled up and away as they should be when opening to reload, but as you say by this point the volatiles should be burnt off...

The issue of getting everything to burn thoroughly in such a way that leaves nice hot coals seems to be something of an elusive beast; it sounds like I need to keep experimenting; thanks for your advice.

 

[Poindexter]

I ever get to visit the UK I want to make a point to look at, maybe even operate, some of these stoves.

I am going later today, to look around youtube and the text internet to see what I can learn about this stove, then stick all that in the back of my mind and see what I wake up with tomorrow morning.

 

[Sir Logsalot]

I ever get to visit the UK I want to make a point to look at, maybe even operate, some of these stoves.

I am going later today, to look around youtube and the text internet to see what I can learn about this stove, then stick all that in the back of my mind and see what I wake up with tomorrow morning.

Thanks very much; it seems that this issue is not uncommon. Outside of this forum there are several other posts about this specific stove that bemoan the same issue. Whilst I am relatively new to this and appreciate there is a strong likelihood of user error, I have followed all instructions to the letter and the results seem less than optimal especially when compared to my friends larger yeoman stove which draws smoke out of the flue consistently whether open, closed or anywhere in between, regardless of opening speed and even vent positions.

 

[begreen]

Does this stove have 3 manual air controls, (airwash, primary, and secondary)? If so, I can see how it might take some getting used to operating it well. Most stoves sold here have one air control. The stove geek in me likes all that manual control, but it could get fiddly until a formula is established.

 

[Poindexter]

My first impression is this stove, and the bulk of the Morso line as well, just don't have a lot of depth of firebox front to rear.

Fluid dynamics is a very complex subject, and the driver; that is to say the suction provided on the firebox by the flue pipe, is both highly variable and constrained by the upper baffle plate.

What is happening with these stoves when the door opens is the glowing coals in the floor of the firebox are making more push than the chimney draw is providing suck.

Reasonable youtube here and mfr's product home page there:

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https://www.stovax.com/stove-fire/stockton-wood-multi-fuel-stoves/stockton-5/

I'll stew on it overnight as an interesting problem that is not related to my job.

 

[Sir Logsalot]

Does this stove have 3 manual air controls, (airwash, primary, and secondary)? If so, I can see how it might take some getting used to operating it well. Most stoves sold here have one air control. The stove geek in me likes all that manual control, but it could get fiddly until a formula is established.

Hi, yes there are 3 controls on this model;

1. A secondary on the underside which is 100% open when forward and 15% open when all the way to the back.
2. A primary at the base of the door.
3. An airwash at the top of the door.

The manual says that after first lighting the fire all controls are fully open, then after around 10 mins when up to temp the primary is closed along with the secondary so that the fire is controlled only using the airwash. Before reloading it says that the airwash should be opened fully for a few minutes and the door opened slowly....except this leads to the sweet smell of bonfire in our lounge unless the embers are very anemic and the flue temp is then getting very low....

I agree that this feels very much like having to solve a formula; I like having the control and have no issues with getting the fire going and regulating the burn. The wood catches well and flue temps climb nicely before turning down the airwash to the optimal central setting. It's just the damn reload that is giving me a headache...

I've received a helpful suggestion from another user via message which I'll try later on and will report back if I do figure this out...

 

[Sir Logsalot]

My first impression is this stove, and the bulk of the Morso line as well, just don't have a lot of depth of firebox front to rear.

Fluid dynamics is a very complex subject, and the driver; that is to say the suction provided on the firebox by the flue pipe, is both highly variable and constrained by the upper baffle plate.

What is happening with these stoves when the door opens is the glowing coals in the floor of the firebox are making more push than the chimney draw is providing suck.

Reasonable youtube here and mfr's product home page there:

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.

Accept third party cookies

https://www.stovax.com/stove-fire/stockton-wood-multi-fuel-stoves/stockton-5/

I'll stew on it overnight as an interesting problem that is not related to my job.

100% agree on this; I was struck by just how shallow the firebox is, to the extent that it's hard to fit anything longer than a 6 inch split from front to back. When building the lattice stack for a top down burn this often results in having to skew the upper smaller splits on the diagonal in order to fit them in.

I've tried every orientation and the best for the lower/main logs is 90 degrees to the door/from west to east, making sure to leave at least an inch of space at the front and rear otherwise the logs remain partially unburnt in those areas.

Equally the lack of depth to the firebox and the proximity of the flue entry slot (in front of the baffle) being SO close to the door makes it feel like a bit of a losing battle at the moment. If I allow the fire temp to drop as the coals burn down in order to avoid any smoke, the flue temp is losing so much heat, thereby seemingly affecting the draw....

My friend is convinced that this is not normal and is quite an experienced stove user who suggested I consult this forum....

 

[Sir Logsalot]

A quick update following a bit more trial and error;

1. I took EatenByLimestone's advice of allowing the volatiles to burn off and considered the info Poindexter provided regarding flue suction and the constraint of the baffle on the draw; it seems that if I wait until the point where MOST have burnt off but not all (ie still some flame left in the firebox), this allows the flue to remain nicely hot so that it continues drawing properly and doesn't produce smoke when opening the door (YAY!) but even better this allows newly loaded splits to take properly (rather than smouldering out/partially burning like they do if I wait until the coals are completely devoid of flame)
2. I considered Begreen's and Moresnow's suggestions regarding the balancing of the controls and found that by leaving the primary alone altogether after lighting, everything works best with leaving the secondary slightly more open throughout all stages of the burn including reloading.
3. I found that when reloading, if I include my usual 2 large splits on the embers but then also put a couple of small splits on top of these, the fire takes much more quickly and even across the full length and height of the logs; it seems that maintaining the temperature of the firebox and flue is vital to the correct function of the stove. Even a sniff of things cooling down seems to lead to issues.

I'll continue to post if I uncover any other findings or issues just in case others are encountering this same problem; thanks to all for their input and advice, I'm very grateful to be (mostly) smoke free now

 

[BillBurns]

Sounds like a draft issue.

 

[dl8860]

@Sir Logsalot I have a stovax county 5 wide and it sounds like our stoves operate almost identically, pulling off a reload with zero smoke entering the room is a small miracle.

On your point 2 above, have you been leaving the secondary open a bit more? I've have mine juuust forward, as in not quite fully closed, as I'm paranoid about not burning secondaries.

Also wondering how you find the stoves heat holding capacity? I feel like once logs start to reduce down a bit to coal the temperature can easily drop from 400F to 300F quite quickly. Any thoughts?

 

[Sir Logsalot]

@Sir Logsalot I have a stovax county 5 wide and it sounds like our stoves operate almost identically, pulling off a reload with zero smoke entering the room is a small miracle.

On your point 2 above, have you been leaving the secondary open a bit more? I've have mine juuust forward, as in not quite fully closed, as I'm paranoid about not burning secondaries.

Also wondering how you find the stoves heat holding capacity? I feel like once logs start to reduce down a bit to coal the temperature can easily drop from 400F to 300F quite quickly. Any thoughts?

Hi,

Yes we had considered the wide model ourselves as it looks great, but we didn't quite have the space available in the chimney breast: assuming it's a fairly recent model you have, then I'd imagine all controls are exactly the same.

Having got used to the stove a little bit better I'm managing to get (mostly) smoke free reloads by following a specific process, which I'll detail below. To someone who doesn't have this frustrating issue the following may all sound a bit boring, but if you're anything like me, you'll be wanting as many specifics as possible; the key seems to be achieving a hot bed of embers and keeping a nice hot flue using a laser thermometer to check flue temps ( I use a Bosch one):

1. I build the fire for a top down burn, on a bed of ash around 1" thick; Firstly I place a few very small (1cm thick) strips of kindling onto the bed of ash, then place 2x medium splits of oak (approx 3 to 4" square by 10" long) on top of these strips (to encourage airflow under the stack) Note that these bottom splits are parallel to the door with enough space at the front and rear so as not to touch the log guard or the back of the stove.

2. I then build a lattice with progressively smaller splits, including a few tiny pieces of larch/softwood in amongst the spaces between the splits (not too many though as I find you need to encourage as much airflow as possible). I then top this off with a firelighter and possibly pop another one in the middle of the stack.....note that I often need to skew these upper splits due to the shallowness of the firebox....

3. I open all controls fully and light it up; the stack will quickly catch and start smoking slightly before it gets going. I'm able to completely close the door after around 20 seconds without the fire going out.

4. Once the fire is going properly after around 10 minutes, I close the primary and leave both the secondary and airwash wide open. At this point I use a laser temperature thermometer to observe the flue temps. Once the flue reaches around 200c approx 8 inches up the flue, I close down the secondary to around 50% and do the same with the airwash. If temps keep climbing beyond 220c 8 inches up the flue, I'll close the secondary down completely and throttle the airwash until temps stabilise.

5. Around 5 mins before reloading I open the secondary and primary fully until most of the flames have died out. Timing is absolutely critical as you want to ensure the temp of the flue doesn't drop below 200c at 8 inches up the flue, otherwise the draw is affected and you're back in Smoketown. Keeping a hot flue is more important than waiting for the flames to die out in my experience.

6. For the reload, I crack the door for 10 seconds and open it slowly. Most of the volatiles will have burnt off and you should be largely smoke free. I spread the embers and place the new logs quickly before they start smoking. I've found that using 3 medium splits rather than 1 large one gives the most quick, even and regulatable heat. With the door closed these quickly catch and after around 2 minutes I can throttle the secondary to around 50% and the airwash the same.

7. I rinse and repeat this until I have to go back into the garden in the snow and chop more logs while my wife stares at me though the window from the warmth of a freshly heated lounge.

Regarding your question about the secondary, my understanding is that in the fully closed position, there is still air flowing in (around 15% if I remember correctly). At it's most closed, I tend to have the secondary slightly more open than this unless the fire is really raging; a sweet spot seems to be opening to 50%, then pushing it to the back until it starts to whistle slightly, then opening it a hair to stop the whistle. I think this would be around 30% open.

In regards to the heat holding capacity I would say not great but its definitely a stove that needs to be run hot, otherwise you'll be forever trying to revive it and being forced to open the door to tend to it with a cooled down flue, which as we both know is the recipe for disaster. 8 inches up the flue, I think around 230 to 240c should be your upper bound.

Any other questions, let me know....

Out of interest where are you taking your temp readings?

Perhaps we should start a Stovax Stockton support group 😄

 

[CBstockton5wideon]

Hi Log burning lovers. I have a Stockton five wide smokes everytime on reload. I have tried most obvious things. How high is your flue? What gap do you have behind the fire?

I live in a bungalow now but in my previous house (a new build) I had a Stockton 5 2015 non eco which didn't smoke at ALL on reload.

Should these wide models be recalled???

Any replies will be greatly appreciated.
Cheers Cal

 

[begreen]

This is not uncommon with wide stoves that have large doors and a shallow firebox. When the door is opened it can pull smoke out. The stove needs a strong draught to stop smoke spillage. I had this issue when running the Jotul F400 at temperatures above 45ºF outside in spite of having a 20' flue system. The solution for me was to never open the stove door while flames were present and the wood was still outgassing. At the later coaling stage, the procedure was to open up the air control fully, wait a full minute, then open up the door an inch to let the pressures equalize, then open up the door slowly.

 

[Sir Logsalot]

Hi Log burning lovers. I have a Stockton five wide smokes everytime on reload. I have tried most obvious things. How high is your flue? What gap do you have behind the fire?

I live in a bungalow now but in my previous house (a new build) I had a Stockton 5 2015 non eco which didn't smoke at ALL on reload.

Should these wide models be recalled???

Any replies will be greatly appreciated.
Cheers Cal

Flue 9m approx.
2" gap behind stove.
Shallow firebox design = smokey reload IME
Get a laser thermometer to check temps and keep the flue hot.
Reload as per Begreens suggestion.
IME when the flames are nearly dying out but the flue is still reasonably hot is the best time to do this.

 

[Muddy42]

I'm afraid this is a common problem with ecodesign stoves. They are designed to achieve maximum burn efficiency and very clean smoke. They do this by recirculating and reburning the gases again and again. However simplistically this is achieved via a narrow opening from the stove to the chimney, often this is also too close to the door. This design works in perfect conditions and masses of draft - straight flue, no downdraft, perfect weather etc. but if anything is amiss they are difficult to light and send smoke back into the room.

I have two identical flues - the 30 year old Clearview stove is fine, the new Esse One Ecodesign is a nightmare! What is the point of a stove that sends clean smoke outside if it fills my house with smoke? Cynically these stoves are also good business for stove installers, because people need help with flue liners, extra ventilation, cowls etc.

I am not familiar with a Stovax but I have adapted my Esse to assist airflow in and out of the stove, which has helped alot. And yes I am aware this has probably nullified the warranty.

 

[begreen]

When a stove has nothing between the fire and the sky above, it will draught easily with almost no flue. Modern stove burn cleanly and properly, but they often take changing burning habits and learning new ones. In general terms, a deeper firebox will have less issues with smoke spillage during mild weather burning than a shallow one.

 

[AlexVanBC]

Thanks; this does seem to make things better regarding the smoking but the difficulty I'm facing is the inconsistent burn of the leftover coals. When I crack open the door they often reignite and will smoke if i open the door fully to reload, leading to an extra couple of cycles of cracking the door open and closing again to get everything completely burned, by which point much of the heat from the fire and the flue is gone. Enough heat remains to catch new logs but these burn inconsistently (from the bottom up) with the tops being only partly charred unless turned (resulting in more smoke).

I'm using the controls correctly as far as I'm aware; after starting I close the primary after around 10 mins and throttle the secondary to around 15%, then using the airwash to control the fire. It's normally set at the centre (optimum burn). When reloading I open the airwash and secondary well before opening the door.

All wood is below 20% dry MC.

I am having this exact issue with my Ambiance Elegance. Driving me crazy and smoking out the house. Nothing I can do helps.

 

[AlexVanBC]

Hi,

Yes we had considered the wide model ourselves as it looks great, but we didn't quite have the space available in the chimney breast: assuming it's a fairly recent model you have, then I'd imagine all controls are exactly the same.

Having got used to the stove a little bit better I'm managing to get (mostly) smoke free reloads by following a specific process, which I'll detail below. To someone who doesn't have this frustrating issue the following may all sound a bit boring, but if you're anything like me, you'll be wanting as many specifics as possible; the key seems to be achieving a hot bed of embers and keeping a nice hot flue using a laser thermometer to check flue temps ( I use a Bosch one):

1. I build the fire for a top down burn, on a bed of ash around 1" thick; Firstly I place a few very small (1cm thick) strips of kindling onto the bed of ash, then place 2x medium splits of oak (approx 3 to 4" square by 10" long) on top of these strips (to encourage airflow under the stack) Note that these bottom splits are parallel to the door with enough space at the front and rear so as not to touch the log guard or the back of the stove.

2. I then build a lattice with progressively smaller splits, including a few tiny pieces of larch/softwood in amongst the spaces between the splits (not too many though as I find you need to encourage as much airflow as possible). I then top this off with a firelighter and possibly pop another one in the middle of the stack.....note that I often need to skew these upper splits due to the shallowness of the firebox....

3. I open all controls fully and light it up; the stack will quickly catch and start smoking slightly before it gets going. I'm able to completely close the door after around 20 seconds without the fire going out.

4. Once the fire is going properly after around 10 minutes, I close the primary and leave both the secondary and airwash wide open. At this point I use a laser temperature thermometer to observe the flue temps. Once the flue reaches around 200c approx 8 inches up the flue, I close down the secondary to around 50% and do the same with the airwash. If temps keep climbing beyond 220c 8 inches up the flue, I'll close the secondary down completely and throttle the airwash until temps stabilise.

5. Around 5 mins before reloading I open the secondary and primary fully until most of the flames have died out. Timing is absolutely critical as you want to ensure the temp of the flue doesn't drop below 200c at 8 inches up the flue, otherwise the draw is affected and you're back in Smoketown. Keeping a hot flue is more important than waiting for the flames to die out in my experience.

6. For the reload, I crack the door for 10 seconds and open it slowly. Most of the volatiles will have burnt off and you should be largely smoke free. I spread the embers and place the new logs quickly before they start smoking. I've found that using 3 medium splits rather than 1 large one gives the most quick, even and regulatable heat. With the door closed these quickly catch and after around 2 minutes I can throttle the secondary to around 50% and the airwash the same.

7. I rinse and repeat this until I have to go back into the garden in the snow and chop more logs while my wife stares at me though the window from the warmth of a freshly heated lounge.

Regarding your question about the secondary, my understanding is that in the fully closed position, there is still air flowing in (around 15% if I remember correctly). At it's most closed, I tend to have the secondary slightly more open than this unless the fire is really raging; a sweet spot seems to be opening to 50%, then pushing it to the back until it starts to whistle slightly, then opening it a hair to stop the whistle. I think this would be around 30% open.

In regards to the heat holding capacity I would say not great but its definitely a stove that needs to be run hot, otherwise you'll be forever trying to revive it and being forced to open the door to tend to it with a cooled down flue, which as we both know is the recipe for disaster. 8 inches up the flue, I think around 230 to 240c should be your upper bound.

Any other questions, let me know....

Out of interest where are you taking your temp readings?

Perhaps we should start a Stovax Stockton support group 😄

This is all great advice but my issue is when the wood burns unevenly. You may be down to embers for the most part but one other bit maybsirll be burning. If you wait, you’ll have no embers left.

 

[Muddy42]

Yes these modern eco design stoves can be a bit temperamental. Firstly are you sure the flue has a metal liner installed, unlike older stoves they dont work well at all without a liner. Then look at the design - often the ceiling baffles allow only a narrow gap for smoke to escape. If the baffles are made of vermiculite, you can replace them with slightly smaller panels. Ive done this.