Help on Green mountain 60

[rashomon]

@tabner Sorry for the delay in my reply, it was one of those weeks.
Yes, I have the Green Mountain 60. Since posting my situation has only worsened. Each day I tried smaller cut up pieces of wood and used more kindling but every time I smoked out my entire house worse than the last. Any possible draft became non-existent as if the bypass was completely closed. I did see smoke coming from the chimney though.

I finally got a good look at the chimney cap during the day today. The spark arrestor screen is almost completely blocked! This stove and chimney is two months old!

How can this happen in two months?! We noticed the first issues during the wind a few weeks ago. I thought wind was supposed to increase the draft. We live on the side of a mountain at 7500' and need a stove the most during the cold windy days. I thought the chimney was too short or something.

Just before Christmas we had the arctic blast where we experienced 48+ hours of below zero temps. It wasn't too windy and the fire was going great. Could the cold weather of created an accumulation of creosote? Immediately after this period I thought it was high winds causing me to have great pains getting the fire going (smoking out the house), but after it was lite all was well. Then this past week I couldn't even get it lit.

I'm still waiting for my moisture gauge to use on my wood but Colorado is so dry I assumed this wouldn't be an issue. My wood is mostly from tree I downed over a year ago although only recently split. I took the cap off and the inside of the chimney looks okay. Here's some pictures.

 

[tabner]

Unfortunately, I think wet wood is the likely culprit.

 

[tabner]

Unfortunately, I think wet wood is the likely culprit.

If it makes you feel better, as far as “assuming” the wood would be dry enough, I have oak which was split and stacked over 4 years ago, I assumed it would be dry enough, its not. because I stacked the rows tight together and covered it in tarps. It still blows my mind that that wood isn’t fully dry.

 

[rashomon]

@tabner Your honest opinion is much appreciated. That's a lot of creosote. Should I be worried about if my catalyst was damaged? My wood is all pine, so maybe that was a factor? I live in a pine forest so that's not going to change.

Do other wood stoves not have any issues with smoke coming in when cracking the door open? Even on it's best day the Green Mountain 60 does seem to let in smoke when adding logs (unless it's the end of a burn and there is no smoke).

You said I should get more than 3 hours on a refill of wood? Is this with hardwood or should that be with pine too? In this video a shop loads the GM60 and is able to relight after a 19 hour burn! Maybe I don't load it up full enough?

I've read wind is supposed to help a chimney draft faster. If I'm getting a backdraft does that signal my chimney is definitely too short?

Were you serious about that primary air hole being called the doghouse? Ha. If so I must not have lurked here long enough to see it referred to that.

 

[tabner]

There are people here more knowledgeable than me with regard to chimneys and creosote than can comment on the safety level of your photos. It doesn’t look great to me.
It does look almost like maybe fly ash though? So maybe the damp pine is just clogging things up, as opposed to 100% creosote.

I do have to be very careful when I open the door to load, this stove is definitely prone to smoke spillage. But I think with all these epa stoves they say to wait until you’re down to coals before reloading anyways.
I would think with a full load of dry pine you’d get more than 3 hour burn time. I can get 7 to 8 hours with oak.
Definitely dry wood is going to help with all of your issues. Whether or not it 100% solves them all or not, I cannot say.

 

[mdocod]

@tabner Sorry for the delay in my reply, it was one of those weeks.
Yes, I have the Green Mountain 60. Since posting my situation has only worsened. Each day I tried smaller cut up pieces of wood and used more kindling but every time I smoked out my entire house worse than the last. Any possible draft became non-existent as if the bypass was completely closed. I did see smoke coming from the chimney though.

I finally got a good look at the chimney cap during the day today. The spark arrestor screen is almost completely blocked! This stove and chimney is two months old!

How can this happen in two months?! We noticed the first issues during the wind a few weeks ago. I thought wind was supposed to increase the draft. We live on the side of a mountain at 7500' and need a stove the most during the cold windy days. I thought the chimney was too short or something.

Just before Christmas we had the arctic blast where we experienced 48+ hours of below zero temps. It wasn't too windy and the fire was going great. Could the cold weather of created an accumulation of creosote? Immediately after this period I thought it was high winds causing me to have great pains getting the fire going (smoking out the house), but after it was lite all was well. Then this past week I couldn't even get it lit.

I'm still waiting for my moisture gauge to use on my wood but Colorado is so dry I assumed this wouldn't be an issue. My wood is mostly from tree I downed over a year ago although only recently split. I took the cap off and the inside of the chimney looks okay. Here's some pictures.

View attachment 307238 View attachment 307239 View attachment 307240 View attachment 307241

Your chimney cap looks the way ours used to get on a custom wood stove that my Father-in-law and myself built years ago. We welded about 200lb of steel onto an old Fisher insert, converting it into a freestanding stove with a big heat sink baffle affair box on top of the rear of the firebox for the exhaust to pass through.

The modification ensured that we robbed most of the heat from the fire and kept it in the house, but it also meant that is was functionally a condensing appliance at that point. The chimney and cap required very frequent attention.

Some things I learned from that experiment, as well as from running new EPA stoves, including a CAT and non-CAT stove recently, all burning pine (we also live in a pine forest), might be applicable to your situation:

Pine is full of resin. Resin produces sooty smoke when burned that needs to be burned off in a HOT fire otherwise it will settle out onto everything in the chimney system, and can even plug up your cats if things aren't hot enough. Make sure to run your stove hot enough to cleanly burn off as much of this as possible in the stove, and EGT's high enough to hopefully expel any that didn't burn.

Avoid "continuous feed" of a log or 2 at a time on a coal bed. Cycle the stove with larger loads of wood spread out further so that the dirtiest part of the burn for each log is happening with a bunch of other logs all feeding a very hot secondary combustion and active cat. The hot fire burning in the tight gap between a full load of wood and the bottom of the firebox baffle, is a soot eating machine.

Make sure to bypass the cats whenever the door is opened. Allowing flames to lick the cats is bad for it and could lead to more rapid deposits/plugging. Also, when the door is open ash can be sucked up into the cats.

Make sure the stove and chimney system are given an opportunity to "clear their throat" both when building fires from cold and when reloading wood. When firing up a load of wood from cold or on a bed of coals, leave the door of the stove open and even open a nearby window a few inches to ensure there's plenty of air for the stove to suck into the box and up the chimney. Allow the fire to build from steady flames into a raging rumbling rocket-stove like affair, with flames being vigorously sucked around the front edge of the baffle, all the way back through the bypass. and up into the stove pipe. If the stove pipe were transparent you would see flames wrapping up the stove pipe several inches or more. This raging draft helps blast soot and other deposits off of the chimney cap, and will even help dislodge and blast out larger chunks of light weight "sooty/ashy" deposits. It also rapidly heats the chimney system and cap, to help reduce the chances of forming new deposits once the door is closed.

After closing the door, leave the air control wide open until your EGT's are good and hot. I aim for 700-800F readings on a FlueGard probe, but it does read a bit high on single wall, so maybe 600-700F would be a good target as a minimum for initial startup to ensure we get the chimney system heated up properly. Remember most stove pipe and chimney systems are rated for continuous operation at up to 1000F so there's lots of margin here. Don't choke down a stove until the fire has spread to all logs and is burning vigorously in the box with the air control open. I usually engage the cat at around 500-600F EGT's.

 

[rashomon]

@tabner Thanks again for your input. And @mdocod thank you kindly for jumping in with such detail and knowledge learned from your experience! This is a ton of knowledge that I love to know, and answered questions I hadn't even had yet.

I added a blower to my stove a month ago to pull more heat from it, and afterwards noticed doing so does rob from the cat temps. I've been careful to keep it in the active range so as not to damage the cat, but it became a battle as my chimney cap was slowly choking itself. I certainly made the issue worse the last 10 or so burns where I ended up smoking out my house. I didn't realize the exhaust issue and was trying to activate the cat hoping that additional burn would add the heat needed to get the stove operating properly. This was pushing smoke from what may be high moisture pine through the cat repeatedly as the fire always smoldered out. Do you know how likely this may have damaged the cat?

I have been making sure to get my cat temps up past halfway towards to 'too hot' range to intentionally help burn off any soot, but this was 10+ days back before the issues in my last paragraph. Now that I replaced the cap yesterday it's working great and I made sure to give it a long hot burn. I've never been able to get it past 3/4 the way to 'too hot', maybe because of the pine.

The forgot to add an spark arrestor screen to my cap, since you also live in Colorado do you feel these are crucial to prevent fires? How often do you need to clean yours? By the way I have family that also live near the Black Forest.

You and Tabner both educated me that I'm not supposed to be feeding these stoves one or two logs at a time. I've been doing that the past 2 months since first using it. To bad it wasn't explained to me sooner but I'm glad I know now. Would the dirtiest part of the burn be at the beginning when the moisture is burning out? I haven't yet reloaded with a full load because I've been slow feeding it, but the times I've started a full load when cold it seems to create an awful amount of smoke. Because my wood may be too wet I'm imagine I should leave the bypass open during this phase to not cause damage to the cat. Now that the cap is replaced I'm able to crack the door for better draft like you mentioned. But with a new full load do you think the cat can handle the dirty part of the burn so long as it's hot enough and I've 'cleared the throat' like you mention?

On the Green Mountain the cat is in the back past the bypass door so I'm never able to see if flames are ever licking it, but when roaring it's certainly enough to get up through the bypass.

I don't have a flue gas probe, all I have is the cat thermometer that came with the stove. If you feel I should get one do I drill through the double walled pipe to install it?

 

[tabner]

I have the condor stovepipe flue probe thermometer, I think it’s 15$ on Amazon. I like having it. I never see temps over 700 degrees though, I don’t think that’s necessary. This stove tends to run pretty efficiently and my flue gasses hover between 300 and 500. Even on an aggressive startup where I’m breaking in a load I don’t get flue gases above 600. Once the cat is engaged and the blower is on and the air is cut back, flue gases range from 400 peak down to 300 or so during the burn. Then bottom out around reload time.
But yes, I would say you have some resinous pine with lots of fly ash and overall damp wood gumming things up. Do a big reload once the coals have burned down, get it all up to temp and then engage the cat and turn the air down. Do you have a stove top thermometer? It would be helpful maybe to get that info. Mine sits right in front of the flue exit, in hopes that the blower fan doesn’t affect it too much.

 

[tabner]

Also. If you can get your hands on some truly dry wood, even just a couple armfuls, you could run a couple loads of that just to compare and contrast to the issues you’re experiencing now. If it all improves, then you have an idea what the problem is. I think you can buy just a couple 2x4s and burn those? Or some wood scraps, some of the pressed wood blocks from tractor supply, or a couple bundles of the kiln-dried stuff they sell in front of grocery stores

 

[mdocod]

@tabner Thanks again for your input. And @mdocod thank you kindly for jumping in with such detail and knowledge learned from your experience! This is a ton of knowledge that I love to know, and answered questions I hadn't even had yet.

I added a blower to my stove a month ago to pull more heat from it, and afterwards noticed doing so does rob from the cat temps. I've been careful to keep it in the active range so as not to damage the cat, but it became a battle as my chimney cap was slowly choking itself. I certainly made the issue worse the last 10 or so burns where I ended up smoking out my house. I didn't realize the exhaust issue and was trying to activate the cat hoping that additional burn would add the heat needed to get the stove operating properly. This was pushing smoke from what may be high moisture pine through the cat repeatedly as the fire always smoldered out. Do you know how likely this may have damaged the cat?

I have been making sure to get my cat temps up past halfway towards to 'too hot' range to intentionally help burn off any soot, but this was 10+ days back before the issues in my last paragraph. Now that I replaced the cap yesterday it's working great and I made sure to give it a long hot burn. I've never been able to get it past 3/4 the way to 'too hot', maybe because of the pine.

The forgot to add an spark arrestor screen to my cap, since you also live in Colorado do you feel these are crucial to prevent fires? How often do you need to clean yours? By the way I have family that also live near the Black Forest.

You and Tabner both educated me that I'm not supposed to be feeding these stoves one or two logs at a time. I've been doing that the past 2 months since first using it. To bad it wasn't explained to me sooner but I'm glad I know now. Would the dirtiest part of the burn be at the beginning when the moisture is burning out? I haven't yet reloaded with a full load because I've been slow feeding it, but the times I've started a full load when cold it seems to create an awful amount of smoke. Because my wood may be too wet I'm imagine I should leave the bypass open during this phase to not cause damage to the cat. Now that the cap is replaced I'm able to crack the door for better draft like you mentioned. But with a new full load do you think the cat can handle the dirty part of the burn so long as it's hot enough and I've 'cleared the throat' like you mention?

On the Green Mountain the cat is in the back past the bypass door so I'm never able to see if flames are ever licking it, but when roaring it's certainly enough to get up through the bypass.

I don't have a flue gas probe, all I have is the cat thermometer that came with the stove. If you feel I should get one do I drill through the double walled pipe to install it?

Blower:

I would not run a blower on your stove until you have a burn strategy figured out that is hot and clean enough not to plug your chimney cap. Don't rob heat from the system until you have more heat than the system can handle or more than it needs to run without the issues you're having. I have one of those thermoelectric fans, a couple of enameled cast iron steamers, and a long section of single wall stove pipe all acting as heat robbers to my stove system, but I'm burning ~45lb loads of 9% Ponderosa in a Mansfield. That's a whole bunch of dry soft fuel that wants to burn hot and fast. The heat robbers in my application are warranted, as they keep the system from over-heating while putting more heat in the house. If I started burning a wetter, harder wood, I would likely have to make adjustments to the thermal impedance or burn rates of the system.


Built-in Temp Probe :

I think the temp probe on the side of these catalytic Hearthstones can be misleading. If the stove is hot but settled into the coaling stage of the burn, the probe will read "active" despite there not actually being any combustion taking place in the cat. If the blower is cooling the dial face of the probe, it will read lower temps than if not, which may create discrepancies/confusion. Just because the probe is in the "active" range somewhere doesn't mean that we can throw a heap of fresh wood gases at it and expect it to be immediately combusting efficiently. A fresh load of wood will produce relatively cool gases. For me, a full load of wood from a cool start (stove body under 125F), will usually drive that temp probe to about 80-90% of the way to the "too hot" transition line. Subsequent fuel loads in a warm stove on hot coals will usually flirt with and ride right on the "active/too hot" transition on the probe for several hours of the burn cycle. I suspect that the bigger firebox plays a role here, but I would still expect a load of properly seasoned fast burning pine to spike temps closer to the max on that probe, especially with brand new cats, which are known to be a bit more "active."


Flue Temp Probe:

A wood stove is sort of like a 5 speed transmission.
1st gear: light fire / get moving.
2nd gear: door open burn / onramp to highway hard acceleration to 65MPH.
3rd gear: door closed full air burn / continue to accelerate to 80MPH to get around that silly cement mixer and merge into traffic.
4th gear: engage cat / stabilize speed into the flow of traffic.
5th gear: cruise control / cruise control.
Reverse: plugged up chimney cap smoke billowing into house / In-law removal tool.

You can drive a car without a tach and you can operate a wood stove without a temp probe on the exhaust, but you probably won't know exactly where redline is in each gear this way, and also don't have a good visual cue for rev matching or when to shift in general. A temp probe will make it easier to develop a reliable repeatable startup and reload procedure, and well as dial in a healthy cruise setting, however, when driving a car, watching the tac all the time will eventually lead to a crash. Don't forget to watch where you're going! What's happening in the firebox is still the most important indicator of how the burn is going. Temp probes lag behind what is going on.

Double wall requires a "probe" style thermometer, and yes, that means drilling the stove pipe, Install in accordance with the thermometer install instruction. Most call for 18" above the surface of the stove.


Spark Arrestor / Cap:

In dry, fire prone areas like this, I prefer to see a spark arrestor on the chimney cap. We have a standard chimney cap with integrated spark arrestor here. There are lots of factors at play for fire risk from a stove chimney that can add up to very little or significant risk depending on how they all align. I don't think the large-hole screen on most chimney caps is going to stop every possible spark or ember, but nor do I think it's likely to have sparks or embers make their way that high up the pipe except when stove door is open (throat clearing operation). Personally I only burn when temps are below freezing and relative humidity is over ~50%, or some combination of temp/humidity that achieves an equivalent or lower fire danger. I think that, and keeping a cleared, defensible space of minimal surface fuel around your home and on your roof are more important factors than the spark arrestor. This time of year we often have snow cover on the ground, and that puts my mind at ease for burning.

I have not had to do anything special to keep the chimney cap / arrestor clear here. I sweep the chimney about twice per burning season. Otherwise, my plan is to make sure I burn hot enough and clean enough and do routine "throat clearing" exercises of the system to keep the cap clear. I do not like ladders

The stove manual for your Green Mountain 60 actually recommends operating the stove for 35-45 minutes a day at the high-burn-rate (door closed, air control wide open, cat engaged) to help keep the chimney clean. If it's not burning 24/7, then that high-fire burn rate should be done as part of the startup process each time it is fired up from cold. That little 2 cubic foot stove weighs 500 lbs That is a LOT of thermal mass to heat up from a small-medium size firebox. I would be careful not to let the stove putter while the stove is still relatively cold. Let it rip full throttle long enough to warm up the stove pretty good! This will also give the stove a chance to work most of the moisture out of the wood with plenty of active combustion to drive it out the chimney hot enough not to condense.


Cat Damage:

Your cats are probably fine but if your chimney/cap is that plugged up there's a chance your cats are also plugged up. I would inspect them and make sure they are clear, not packed with soot. If they are plugged up use an ash vac (for indoor use) or a shop vac or compressed air (outside!) to clean them out. If they are like mine, they can be lifted out pretty easily for cleaning, check the stove manual for specific instructions on that. At minimum the cats and the various surfaces above the baffle in the stove should be vacuumed every time the chimney is swept.

I think you should engage the cat after a fuel reload or fresh start as soon as you have reached 500-600F EGT's with the door closed and air control wide open. You'll need a flue temp probe to know when this is. If the wood is appropriately dry, and you have the fire properly excited before closing the door, then you should be getting very strong secondary combustion in the stove, and this should be handling 85-95% of the combustion process in the box before anything even gets to the cat. If that's not happening when you close the door, bypass cat and crack the door back open to induce a rocket-stove effect until things are hot enough to roll flames from the secondaries when the door is shut. These stoves run best when operated as hybrids. Steady active primary/secondary flaming combustion through most of the off-gassing part of the burn cycle (~2-3 hours for pine), then after the flames drop out with the wood gas still slowly coming out of the heap of shrunken transitioning logs, that's when the cat should wake up and take over the combustion of wood gases. At this later stage of the burn, the release of wood gases is too slow to sustain active flames in the box, but is still plenty of wood gas to keep the cats going. You'll often see the temp probe above the cat spike the highest during this part of the burn (around the 3-5 hour mark with pine). After that everything should settle down to coals.

If the door is shut I wouldn't worry about flames damaging the cat when its engaged. The biggest risk of damage there is when a hot flame reaches back and is sucked through a cold cat. When the door is shut, the flames and the gases are all steadily moving like a steady river of hot gases and plasma. The design of space above the baffle on these stoves creates a choke point that forces that river of gases to come down and through a slot between the baffle and the bypass assembly before entering the space where the bottom of the cats are exposed. As long as the door is shut, I would expect the slow river of flames to stay up near the roof of the stove. They aren't going to want to naturally traverse down into the choke point.



Other thoughts:

I don't think that 300-500F EGT's is an appropriate goal for soft-wood burning. That sounds like a great range to be on on a steady burn from pitch-free hardwoods, but softwood is full of pitch. If you run your stove with only 300-500F EGT's on pitch-laden softwoods during the off-gassing, resin-soot-release phase of the burn, especially with wetter than ideal woods, you can expect a repeat of that chimney cap situation or plugged up cats. I learned from folks on this forum that the soot needs at least 750F to burn off, and in my experience if there isn't enough extra heat and extra air coming into the system to burn it off, it can drive the cats to an over-rich condition, snuff them out, and plug them up. Not only do soft woods want to burn faster and hotter, they should be allowed to burn faster and hotter for a clean burn that doesn't plug up the chimney or cats

The GM 60 manual says that the stove generally produces 800-1300F EGT's just above the cats.

The popular FlueGard probe for double wall EGT measurements includes the following general purpose instructions to consider:

• 100℉ to 400℉: Temperature too low. Incomplete combustion, causing smoke, soot and hazardous creosote. Open draft and/or add dry fuel.
• 400℉ to 900℉: Safe operating temperature. Complete combustion and best efficiency.
• 900℉ to 1200℉: Wasting energy, possibly overheating. While high temperatures are often reached on initial firing, should not be maintained for normal operation. Reduce draft.

 

[rashomon]

@tabner Thanks again for those final thoughts. I do currently have a Cat thermometer (comes with the GM60) and I think I'll be picking up the FlueGard prob too. And yes, I'll find some really dry wood to do a test burn and see how things run differently. Reminds me, my moisture gauge should be arriving today, maybe I'll find out how bad my wood is!

@mdocod Thanks again so very much for this detailed reply. I feel like I owe you a beer or something for taking the time to educate me with all that information.

I will be adding the Condar FlueGard probe to get the bigger picture on what's happening like you mentioned. I got the impression early on the Cat probe showed a delayed reading because, just like you mentioned, often it would be active even when the fire is almost out. Another prob should help me see what's really happening and help me learn when I need to be "shifting gears"-- great analogy.

My dealer said he's set aside a spark arrestor for me to add to the new stove. Better to stay safe regarding fires.

Since my last post I've been doing what you both mentioned and only reloading a full load once the last is gone to coals. I'm already noticing less attention is needed to keep an eye on things, longer burn times, and appreciate the full load doing it's magic to clear the throat of the stove.

Once I have the flue gauge installed I'll be making sure I get high Flue Temps hot enough (min. 500 degrees), before engaging the cats, and I'll keep an eye on Flue gases to get in the 750+ range to know I'm in the zone to be burning off the soot. For now I'm not closing the bypass until my cat temps are well into the active zone AND I'm keeping strong secondaries confirming my wood is burning hot, efficiently, and most of the moisture is gone.

All these things have been very valuable to learn and I hope others learn from this too by reading these posts. Thank you.

 

[rashomon]

I got my FlueGuard probe thermometer installed and have a completely different picture now. First off, I read on the back of the package these are only rated for 4000 hours because they wear out. Maybe I can get more life because I'm not getting close to 900. But could the same be true about the Cat thermometer that came with the GM60?

There is definitely a delayed response measured by the Cat thermometer compared to the FlueGuard. Both in rising temps and lowering temps.

I have a follow up question about the GM60 though, compared to a larger stove. To maintain 500+ degrees for my Cat I'm realizing I'm burning pretty hard with the air intake mostly open, which is good for heat, but bad for burn times. Is it possible with the GM60 and it's 2 cu ft capacity (and rated BTU @ 60,000) it's designed for less heat? I understand physics might not care about the capacity, but take for instance the Green Mountain 40 with it's much more limited 1.32 cu ft capacity (rated up to 40,000 BTUs). I can't imagine holding a 500+ degree burn for very long in there.

So far getting my EGTs up to 800 seems difficult, unlike the 800-1300 you mention from the GM60 manual. I have a new load of wood that's drier than the last, but still softwood. I feel like I need to burn it with the air wide open for 1.5 hours to maybe get there, popssibly even with the bypass open. The only time I've crossed 75%+ in the active range on the Cat thermometer was with the air wide open. Once I even forgot to close the bypass and it still didn't cross into "too hot" after nearly 2 hours with air wide open. I'll keep an eye and report back if that changes.

If I can't get ideal EGT for the Cat, should I just bypass them when the temps are problematic to preserve their life?

I could easily be wrong or not understanding something because I am new to this and have only monitored Flue gasses for a day. I attached some photos of an example where I would think I had plenty of time left in my large mound of glowing red coals before needing a reload. The Cat thermometer is well into active range, but the FlueGuard probe measures less than 400 and falling. Am I correct this means I need to reload to bring up EGT and not damage the Cats? Or since this is the end of the burn does this not apply?

 

[tabner]

I got my FlueGuard probe thermometer installed and have a completely different picture now. First off, I read on the back of the package these are only rated for 4000 hours because they wear out. Maybe I can get more life because I'm not getting close to 900. But could the same be true about the Cat thermometer that came with the GM60?

There is definitely a delayed response measured by the Cat thermometer compared to the FlueGuard. Both in rising temps and lowering temps.

I have a follow up question about the GM60 though, compared to a larger stove. To maintain 500+ degrees for my Cat I'm realizing I'm burning pretty hard with the air intake mostly open, which is good for heat, but bad for burn times. Is it possible with the GM60 and it's 2 cu ft capacity (and rated BTU @ 60,000) it's designed for less heat? I understand physics might not care about the capacity, but take for instance the Green Mountain 40 with it's much more limited 1.32 cu ft capacity (rated up to 40,000 BTUs). I can't imagine holding a 500+ degree burn for very long in there.

So far getting my EGTs up to 800 seems difficult, unlike the 800-1300 you mention from the GM60 manual. I have a new load of wood that's drier than the last, but still softwood. I feel like I need to burn it with the air wide open for 1.5 hours to maybe get there, popssibly even with the bypass open. The only time I've crossed 75%+ in the active range on the Cat thermometer was with the air wide open. Once I even forgot to close the bypass and it still didn't cross into "too hot" after nearly 2 hours with air wide open. I'll keep an eye and report back if that changes.

If I can't get ideal EGT for the Cat, should I just bypass them when the temps are problematic to preserve their life?

I could easily be wrong or not understanding something because I am new to this and have only monitored Flue gasses for a day. I attached some photos of an example where I would think I had plenty of time left in my large mound of glowing red coals before needing a reload. The Cat thermometer is well into active range, but the FlueGuard probe measures less than 400 and falling. Am I correct this means I need to reload to bring up EGT and not damage the Cats? Or since this is the end of the burn does this not apply?

View attachment 308027

Good Photos, i like them all collaged together like that for comparison. I have the exact same stove and gauges, so i can relate. In the above picture, i would definitely NOT be reloading. i would want to wait until those coals burned down much lower. Both for room on the reload, less smoke into the house, and more efficient burn cycles. You don't need to panic about dropping EGTs on the end of a burn cycle, there should be no moisture in those coals at this point, so you're not generating creosote.
And the difference in the two gauges (the Cat gauge and the Flue Probe) is not necessarily a lag on the Cat gauge. It is quite possible that the cat gauge stays in the active range as it's doing it's job and burning fuel/gasses, but the heat from that catalytic combustion is doing what it's supposed to do - absorbing into the top of the stove and being released into your house, rather than all going up the chimney.
I have definitely noticed with this stove my Flue Probe Condor, never goes very high. It peaks on a hot reload around 500 to 600. Most of my burn cycle it is between 300 to 400 during the more aggressive part of the burn, and as you can see from the photos i'm about to post, it drops down to 200~300 during the coaling stage. @Nigel459 has years of experience with the BK, and now runs a GM40, and he has observed the same thing, pretty low temps out of this model considering it's a secondary burn stove. some might disagree, but to me I think it's because this stove is pretty efficient. I also have the blower kit, so my feeling is that i'm pulling a lot of the heat off the top of the stove, increasing efficiency, and somewhat cooling those EGTs before they go up the stack. But others may disagree with me here.

 

[tabner]

 

[tabner]

Our stoves are currently in very similar stages of their burn cycle, lol. That was a load about 75% full, loaded N/S of mostly Maple with a little Oak, i put in at 8am this morning. had the finished basement around 80 all morning, and brought the temp on the main floor of the house up from 68 to 70, with no other heat source up there, and it's about 40 outside right now (30 this morning). I just opened up the air control all the way, not cause i'm worried about the EGTs or the Cats, just because if i dont that coaling phase will last forever and i need to get another load in this afternoon. Probably about 45 mins or an hour from now i'll reload, that'll have the upstairs around 72 by the time the wife comes home from work, and that'll take me up until the nighttime reload happens around 8pm.

 

[rashomon]

@tabner - It's great to hear your experience considering you have the very same stove and it is seems to behave the same. Nice photos yourself! I'll keep learning here because everyone else's advice is good to know, reading may just be different considering variables? For instance, I did forget to mention I was still using my blower as well. Perhaps EGT would be higher with that off.

I struggle visualizing how stuff a full load should be. This morning I managed what may be 100% and it was touching the baffle, sometimes a big log with knock the metal baffle end off and I need to stick it back on. I'll load it whichever direction I can maximize the load. This time it was left to right (so I assume E to W?).

In the past I did smaller loads but thought I should maximize once I realized I shouldn't be continuously loading. My burns times have since increased but still don't last much more than 4-5 hours (which seems to depend on how fast it's burning, maybe due to some loads being drier for some reason). I'd dream of an overnight burn like it appears a dealer was successful with in the video I posted earlier in this thread. I heard my gas heating system kick on at 3am because the fire was long out and my house dipped to 60.

For a full day I load it up 4 times. 7:30, 12:00, 4:30, then 8. HearthStone claims "24 total hours of usable heat from a single load of wood". But then again my hottub claims to only use $250 electricity a year.

 

[begreen]

@tabner Your honest opinion is much appreciated. That's a lot of creosote. Should I be worried about if my catalyst was damaged? My wood is all pine, so maybe that was a factor? I live in a pine forest so that's not going to change.

Do other wood stoves not have any issues with smoke coming in when cracking the door open? Even on it's best day the Green Mountain 60 does seem to let in smoke when adding logs (unless it's the end of a burn and there is no smoke).

You said I should get more than 3 hours on a refill of wood? Is this with hardwood or should that be with pine too? In this video a shop loads the GM60 and is able to relight after a 19 hour burn! Maybe I don't load it up full enough?

I've read wind is supposed to help a chimney draft faster. If I'm getting a backdraft does that signal my chimney is definitely too short?

Were you serious about that primary air hole being called the doghouse? Ha. If so I must not have lurked here long enough to see it referred to that.

Describe the flue system from stove to chimney cap including elbow, tee, and chimney height. Masonry or metal?

 

[rashomon]

Describe the flue system from stove to chimney cap including elbow, tee, and chimney height. Masonry or metal?

My flue comes straight out of the top of my GM60 and goes straight up all the way to the cap (there are no bends, elbows or tees). The entire way it is double-walled 6" DuraVent metal pipe. About 18' total - (6.5' to ceiling, passing through a deck off the master bedroom above it, then an additional 10' to the cap). I only recently received my wood moisture tool, and I do believe much of my wood was around 15% or more which I assume was the issue. I'm burning different wood which appears to be going much better, but of course I also have a brand new cap without spark arrestor for the time being (so nothing is clogged). The new cap spins with the wind and I haven't encountered any issues. This morning I noticed a small moment of backdraft when lighting the fire. I wonder if at that moment the wind changed direction and it spun correct.

I hear the issue with these are they will get clogged and stop working. If that happens and instead turns into a funnel for wind coming head on into it that will be a nightmare. I'll hold onto my other cap and clean it so I can switch it quickly if that happens. Although ultimately I'm confused why the wind isn't causing it to draft more like I've read it should. There is a nearby roof but the height was installed to maintain the needed rules. I guess I need to double check their work... I do like on the side of a mountain overlooking a canyon 2000' below. The winds can be really strong depending on the weather.

 

[tabner]

I’ll document a burn cycle for you here, in case that’s helpful. 3:50 reload. The photos of the reload are hard to judge cause of the glare, but there are some big gaps up top, it’s only 70% full maybe

 

[tabner]

Took a little while to get going good. But at 4:20 photos are below. Shut the bypass at this point. Another 10 mins and stovetop climbed to 450 and EGT at 375. Shutting the air down. Closed it down a little more than halfway to start with. In another 15 mins I’ll shut it almost all the way.

 

[tabner]

Last one. 5pm now and below photos show where everything is at. Air is 100% closed down (has been for the last 15 mins). And I’m going to go upstairs and leave the stove alone now until 9pm.

 

[rashomon]

Thanks for that! I see what you mean by North/South loading there, and by 70% (taking into account space at the top of in between logs. I'm ready to reload myself.

My last load was as close to 100% as I can imagine, totally filled with larger split portions close together. It barely lasted 3.5 hours and my temps were never near high on the EFT or Cat.

 

[tabner]

Thanks for that! I see what you mean by North/South loading there, and by 70% (taking into account space at the top of in between logs. I'm ready to reload myself.

My last load was as close to 100% as I can imagine, totally filled with larger split portions close together. It barely lasted 3.5 hours and my temps were never near high on the EFT or Cat.

Softwood or hardwood? My next thought would be moisture content. I definitely get hotter temps on both stove top and flue with dryer wood

 

[rashomon]

Softwood or hardwood? My next thought would be moisture content. I definitely get hotter temps on both stove top and flue with dryer wood

Pine is all I have, I live in the mountains. I've got a moisture reader finally so I'm doing what I can to stick to drier wood. It sure burns hotter. I just wish I got a Green Mountain 80 because the 60 isn't enough output for my space when outside temps are below 40, and I'd imagine the larger capacity would offer longer burn times. Every 3-4 hours is too often to ever last overnight.

I can't understand the claim it offers "24 total hours of usable heat from a single load of wood". To get that I imagine it's barely warm to the touch at hour 24 in a Miami test lab using kiln dried oak filling 100% the capacity with air intake closed.

Since the Green Mountain 80 claims 30 hours I might be successful with a realistic overnight burn that lasts 8 hours.

 

[rashomon]

I'm posting this just for fun (and also for my own reference). I let my burn go as hot as I've been able to get it on my Green Mountain 60 tonight. It burned with air control wide open, and my blower off, for a little over an hour, the last half with the cat engaged. I haven't seen my cat temps get this high, but I'm only burning softwood (pine) It appeared to have maxed out and wasn't getting higher. At the beginning it was about 75% full, loaded East/West.

After I took the photos at 7:45 I put my blower on high, and then shortly after I cut the air to medium-low (the manual states that is 1/4" pulled out from closed -- closed isn't really closed but it's as far as you can close it, air still does come in).

This is where I ended up at 8:10.