New gasifier furnace issues

[RogerD]

Hi all. Im new to this forum. This year i replaced a newmac wood/oil combo furnace for a airbilo plus (similar to a max caddy) made here in quebec. The newmac was installed in 2008 and we bought the farm in 2012. It was poorly installed. Basically went from 8" pipe at the stove with 2 90° turns then reduced to 7" with another 90 out to the ceramic chimney which was 6". Backdraft issues and just poor runs times got me hating that unit fast. Oil worked perfectly.

This year i had a 7" ss liner installed. Approx 20' chimney. We moved the new furnace forward 4 feet to allow a 6" elbow and pipe to connect straight up to the 7" liner. In total, theres a 45° connecting to the liner then it turns 90° up the chimney. The chimney is outside of the house.

Here is my short term issue. Ive been running the stove a little on the cooler nights we have had. Most run time was 2 days straight. I noticed that this unit takes a good hour to heat up and get good heat coming out. I open the damper fully to allow the flue and stove to get hot while charring up the wood. Maybe 20 minutes on a fresh start and 10 minutes when adding wood. I checked my heat exchanger and inside my flue yesterday and noticed that theres a shiny black residue being left behind. I contacted my chimney guy and he said its too early to tell and that i would need a couple months of constant running to know how things are working. It could be the short daily burns causing this.

Things to note:

i did not have my flue draft tested. I dont know anyone with one. Looking into possibly buying my own.

A cap was installed with the liner. Theres no mesh. Just square holes cut all around the cap. Chimney guy mentioned to take the cap off, maybe its reducing my draft.

My firewood was cut and blocked (not split) and piled 2 years ago. I split it all last winter. Piled and covered it for the summer. On a fresh split face its testing from 14-18%. Tester from lee valley.

I notice that my door window gets dirty. The gasification is happening with the damper closed. Sometimes constant, sometimes intermittent.

And lastly, im not filling the firebox full. Im adding 3-4 pieces at a time. Its just not cold enough out and it gets to 23° c plus in the house. Outside temp hovers from -5c to -15c. Could it be the few pieces i put in burn off then when theres coals left its too cold and thats creating creosote?

Some say im overthinking it but after the issues with my newmac, i have reason to be even though i was hoping to have a less stressful burning season being how everything was done to the best that could do.

Appreciate any input. Thanks!

 

[Gbawol42]

Hi all. Im new to this forum. This year i replaced a newmac wood/oil combo furnace for a airbilo plus (similar to a max caddy) made here in quebec. The newmac was installed in 2008 and we bought the farm in 2012. It was poorly installed. Basically went from 8" pipe at the stove with 2 90° turns then reduced to 7" with another 90 out to the ceramic chimney which was 6". Backdraft issues and just poor runs times got me hating that unit fast. Oil worked perfectly.

This year i had a 7" ss liner installed. Approx 20' chimney. We moved the new furnace forward 4 feet to allow a 6" elbow and pipe to connect straight up to the 7" liner. In total, theres a 45° connecting to the liner then it turns 90° up the chimney. The chimney is outside of the house.

Here is my short term issue. Ive been running the stove a little on the cooler nights we have had. Most run time was 2 days straight. I noticed that this unit takes a good hour to heat up and get good heat coming out. I open the damper fully to allow the flue and stove to get hot while charring up the wood. Maybe 20 minutes on a fresh start and 10 minutes when adding wood. I checked my heat exchanger and inside my flue yesterday and noticed that theres a shiny black residue being left behind. I contacted my chimney guy and he said its too early to tell and that i would need a couple months of constant running to know how things are working. It could be the short daily burns causing this.

Things to note:

i did not have my flue draft tested. I dont know anyone with one. Looking into possibly buying my own.

A cap was installed with the liner. Theres no mesh. Just square holes cut all around the cap. Chimney guy mentioned to take the cap off, maybe its reducing my draft.

My firewood was cut and blocked (not split) and piled 2 years ago. I split it all last winter. Piled and covered it for the summer. On a fresh split face its testing from 14-18%. Tester from lee valley.

I notice that my door window gets dirty. The gasification is happening with the damper closed. Sometimes constant, sometimes intermittent.

And lastly, im not filling the firebox full. Im adding 3-4 pieces at a time. Its just not cold enough out and it gets to 23° c plus in the house. Outside temp hovers from -5c to -15c. Could it be the few pieces i put in burn off then when theres coals left its too cold and thats creating creosote?

Some say im overthinking it but after the issues with my newmac, i have reason to be even though i was hoping to have a less stressful burning season being how everything was done to the best that could do.

Appreciate any input. Thanks!

I would say that first hour where your not getting the best heat is where your creasote problems are occurring. It could occur in the end, but usually by end coals all the impurities of the wood have burned off already.

Flue needs to be 300f (about 150c) so cresote won't form. If the fire is smouldering in the beginning and not having secondary burns you are sending that smoke up the chimney, that plus a flue colder than ideal is probably forming creasote.

I find these gassifiers work best with the more wood in them, it's easier to keep the firebox hotter. With mini loads the firebox will lose temp faster since there is less fuel to burn. I'm not saying you can't burn mini loads, you just might have to open the dampener more so it doesn't cool down, especially in the beginning.

Also it sounds like you have seasoned wood, but the wetter the wood again the quicker the firebox cools due to steam. Would hurt to toss some form of thermometer on the flue to get an idea where you are sitting.

 

[RogerD]

I would say that first hour where your not getting the best heat is where your creasote problems are occurring. It could occur in the end, but usually by end coals all the impurities of the wood have burned off already.

Flue needs to be 300f (about 150c) so cresote won't form. If the fire is smouldering in the beginning and not having secondary burns you are sending that smoke up the chimney, that plus a flue colder than ideal is probably forming creasote.

I find these gassifiers work best with the more wood in them, it's easier to keep the firebox hotter. With mini loads the firebox will lose temp faster since there is less fuel to burn. I'm not saying you can't burn mini loads, you just might have to open the dampener more so it doesn't cool down, especially in the beginning.

Also it sounds like you have seasoned wood, but the wetter the wood again the quicker the firebox cools due to steam. Would hurt to toss some form of thermometer on the flue to get an idea where you are sitting.

Thanks for replying. I re thought about my comment on an hour for heat. What i meant was that it takes an hour for the blower to stay on continuously. Before that it runs for 5 then off. My fan limit is set to roughly 100-110f off, 150-160f on. I do open the damper for 15-20 minutes when i start the fire. The flue gets plenty hot but will confirm temp. The fire is roaring at this point. I then shut the damper and allow it to do its thing.

I bought a temp gauge that looks like a meat thermometer. It has a magnet on it and when i installed it, i never thought about the direction the magnet was facing. After testing in boiling water i realised why it wasnt working. It will be a few weeks before i can retest the flue temp due to warmer weather ahead.

 

[RogerD]

This is a view of inside the heat exchanger and the elbow coming out of the furnace

 

[brenndatomu]

Wow, never heard of this brand before...and it does look a lot like a Caddy!
http://www.lsbilodeau.com/en/Catalog/Heating/Furnaces/Air-Bilo.shtml
Buy a Dwyer Mark II model 25 to use on that chimney...they are not expensive and plenty accurate for us wood furnace guys...most people leave them hooked up to check draft whenever loading.
Sounds like those small fires aren't working so we'll...when you load try stacking in criss cross so to make the stack as tall as possible...that will help some. Also use low BTU wood...pine, poplar, soft maple, boxelder, etc. That way you can load more wood (burn cleaner) and not overheat the house. You can add in some real dry stuff like ECO bricks, or used pallet wood too...many places have used pallets laying out back that are free for the taking. A circular saw makes them into firewood in about 60 seconds....

 

[RogerD]

Wow, never heard of this brand before...and it does look a lot like a Caddy!
http://www.lsbilodeau.com/en/Catalog/Heating/Furnaces/Air-Bilo.shtml
Buy a Dwyer Mark II model 25 to use on that chimney...they are not expensive and plenty accurate for us wood furnace guys...most people leave them hooked up to check draft whenever loading.
Sounds like those small fires aren't working so we'll...when you load try stacking in criss cross so to make the stack as tall as possible...that will help some. Also use low BTU wood...pine, poplar, soft maple, boxelder, etc. That way you can load more wood (burn cleaner) and not overheat the house. You can add in some real dry stuff like ECO bricks, or used pallet wood too...many places have used pallets laying out back that are free for the taking. A circular saw makes them into firewood in about 60 seconds....

Hi. I looked up the dwyer. Does it come with a tube that goes into the flue?

I have some poplar in my pile. Ill try that next time. Should my draft be fully closed once the fire is burning good? Im assuming even the slighest extra draft will stop the secondary burn?

I have access to pallets. Ill try that. Do you think the existing creosote will slowly breakdown?

 

[brenndatomu]

Does it come with a tube that goes into the flue?

No, you just need to get some tubing to connect to...some flexible copper has worked well for me.

Should my draft be fully closed once the fire is burning good? Im assuming even the slighest extra draft will stop the secondary burn?

Yeah it should be closed, but cracking it open a bit shouldn't stop the secondary combustion totally...some people leave a nail or paper clip on the damper door to crack it open a bit to get through poor wood, or a cold night, etc.

Do you think the existing creosote will slowly breakdown?

Dunno about breaking down...it might dry up some...the dryer the better, but not being there at all is best. Always a certain amount of fire risk if its still there...

 

[RogerD]

No, you just need to get some tubing to connect to...some flexible copper has worked well for me.

Yeah it should be closed, but cracking it open a bit shouldn't stop the secondary combustion totally...some people leave a nail or paper clip on the damper door to crack it open a bit to get through poor wood, or a cold night, etc.

Dunno about breaking down...it might dry up some...the dryer the better, but not being there at all is best. Always a certain amount of fire risk if its still there...

Ok perfect. Ill try and get my hands on one. It was cool enough this morning to try the stove. Ive been experimenting by watching my temp probe. Upon startup by what the manufacturer calls for, i left the door cracked until the flue gas temp was at 450f. Once it reached that temp, i closed the door with the damper closed. I noticed the fire weaken completely to tiny flames and a dark firebox with no secondary burn. Flue temp was hovering at the 200f mark. Maybe a bit less. So i decided to crack the damper a bit to 1/4" or so. The fire picked back up to a nice yellow flame with a bright firebox. Secondary action was on. Flue temp got up to 400f. I am now trying roughly 1/8" draft opening and flue temps are at 300f with a nice flame.

Now i understand these epa stoves run less flue temps, but would i be safe running at 300f? Again, this is flue gas temp on single wall pipe roughly 20" from the exit of the furnace.

Thanks

 

[Gbawol42]

Ok perfect. Ill try and get my hands on one. It was cool enough this morning to try the stove. Ive been experimenting by watching my temp probe. Upon startup by what the manufacturer calls for, i left the door cracked until the flue gas temp was at 450f. Once it reached that temp, i closed the door with the damper closed. I noticed the fire weaken completely to tiny flames and a dark firebox with no secondary burn. Flue temp was hovering at the 200f mark. Maybe a bit less. So i decided to crack the damper a bit to 1/4" or so. The fire picked back up to a nice yellow flame with a bright firebox. Secondary action was on. Flue temp got up to 400f. I am now trying roughly 1/8" draft opening and flue temps are at 300f with a nice flame.

Now i understand these epa stoves run less flue temps, but would i be safe running at 300f? Again, this is flue gas temp on single wall pipe roughly 20" from the exit of the furnace.

Thanks

You said temp probe so I take it you mean internal pipe temp correct? Just making sure you don't mean outside the pipe like a magnetic temp would read.

I have a heatmax 2, also an epa stove. It "cruises" at around 340f-370f. Meaning it sustains these temps and secondaries are going the whole time.

You might have to bring it up to a higher temp before shutting the dampener, or if you want to shut it at a lower temp you might have to reopen for a round or 2 and let it heat up again.

Someone correct me if I am wrong I believe you need 1100f in the firebox for the smoke to burn, ie the secondaries. So if you firebox doesn't get hot enough it just smolders the logs and doesn't pump out any heat. The heat from these stoves comes from the secondaries, which when running properly will burn less wood than older traditional stoves. Buuuut they have to be running right for this to happen.

I have a temp controller on my stove that closes the dampener at 460f and reopens at 320f, when I am calling for heat. It takes maybe 4 rounds of this before the secondaries are maintaining my cruising temps and it doesn't drop below 350f to reopen the dampener. Before the temp controller I kinda had to babysit my stove for an hour to make sure it is going. However i also know that my wood is about 5% wetter than it should be. So the dryer the wood the easier and less babysitting you need to do.

 

[RogerD]

You said temp probe so I take it you mean internal pipe temp correct? Just making sure you don't mean outside the pipe like a magnetic temp would read.

I have a heatmax 2, also an epa stove. It "cruises" at around 340f-370f. Meaning it sustains these temps and secondaries are going the whole time.

You might have to bring it up to a higher temp before shutting the dampener, or if you want to shut it at a lower temp you might have to reopen for a round or 2 and let it heat up again.

Someone correct me if I am wrong I believe you need 1100f in the firebox for the smoke to burn, ie the secondaries. So if you firebox doesn't get hot enough it just smolders the logs and doesn't pump out any heat. The heat from these stoves comes from the secondaries, which when running properly will burn less wood than older traditional stoves. Buuuut they have to be running right for this to happen.

I have a temp controller on my stove that closes the dampener at 460f and reopens at 320f, when I am calling for heat. It takes maybe 4 rounds of this before the secondaries are maintaining my cruising temps and it doesn't drop below 350f to reopen the dampener. Before the temp controller I kinda had to babysit my stove for an hour to make sure it is going. However i also know that my wood is about 5% wetter than it should be. So the dryer the wood the easier and less babysitting you need to do.

Hi. Yes my readings are internal. I left the damper at 1/8" open and for the past 2 hours it stayed at 300f. Secondary burn was good. It just seemed to work a lot better than before! My blower has been on for 2 1/2 hours and its still going with just coals. Pipe temp now is 200f but theres no more wood to burn, just coals. I burnt roughly 4 pieces of wood thats been piled for 4 years minimum. I tested the moisture this morning and it ranged from 10-15%. Overall i think its better but i will verify my draft.

 

[brenndatomu]

Upon startup by what the manufacturer calls for, i left the door cracked until the flue gas temp was at 450f. Once it reached that temp, i closed the door with the damper closed. I noticed the fire weaken completely to tiny flames and a dark firebox with no secondary burn. Flue temp was hovering at the 200f mark. Maybe a bit less. So i decided to crack the damper a bit to 1/4" or so. The fire picked back up to a nice yellow flame with a bright firebox. Secondary action was on

You shouldn't need to crack the door at all...unless you are lighting up a cold firebox on a warm day and your chimney doesn't want to draft well. You should be able to load the firebox up, light the fire and close the door...you'll want to have the damper fully open until you reach the temp you want in the pipe...then it can be closed...or left open a crack if that's how you find works best for you.
I had a Drolet Tundra, which is basically the same machine as a Caddy, smaller version of the Max Caddy...my experience has been that if fed dry wood it will sustain secondary combustion for several hours after the intial heating of the firebox up to operating temp...which can take a couple rounds of open damper/closed damper as @Gbawol42 mentioned above.

 

[RogerD]

You shouldn't need to crack the door at all...unless you are lighting up a cold firebox on a warm day and your chimney doesn't want to draft well. You should be able to load the firebox up, light the fire and close the door...you'll want to have the damper fully open until you reach the temp you want in the pipe...then it can be closed...or left open a crack if that's how you find works best for you.
I had a Drolet Tundra, which is basically the same machine as a Caddy, smaller version of the Max Caddy...my experience has been that if fed dry wood it will sustain secondary combustion for several hours after the intial heating of the firebox up to operating temp...which can take a couple rounds of open damper/closed damper as @Gbawol42 mentioned above.

In the beginning i was opening the damper and leaving the door closed on startup. The manual had said the door method so i figured id try it. Both methods worked well but i prefer the damper method.

 

[RogerD]

No, you just need to get some tubing to connect to...some flexible copper has worked well for me.

Hi brenndatomu. I received the dwyer mark 2 today. I didnt realize it was such a big unit. Im heading to the hardware store soon to try and find a tube that will work. Should i be measuring with the high or low port?

 

[brenndatomu]

Use the port on the right...high I think it is. You only need the one rubber tube...you can peel the tubes apart and save the other one for a spare or something

 

[RogerD]

Use the port on the right...high I think it is. You only need the one rubber tube...you can peel the tubes apart and save the other one for a spare or something

Got it figured out. Found a copper tube roughly the same diameter as the hose. With the morning coals left in the stove, the pipe was warm. Draft was around .04". I have 2 6" pipes bringing fresh air in the stove room i noticed when i opened my basement door the draft would rise .01". I thought i was bringing enough in. I restarted the fire and with the damper open and the fire going good, draft was at .06".

Per the manual: .04" minimum in the flue.
.06" maximum out of the furnace.
My readings are from my temp probe hole roughly 20" from the rear of the furnace exhaust. Seems like im in the specs. Still making me wonder what is causing the creosote.