Ways to burn cleanly

[hansenjw]

In the article, the third point is to not reload on top of coals. What is the alternative? Is this why people take the coals to the front (or back?) when reloading?

 

[EbS-P]

In the article, the third point is to not reload on top of coals. What is the alternative? Is this why people take the coals to the front (or back?) when reloading?

I took that to mean use kindling to get get a fast fire and not wait for the the coals to light the big splits. I use 2-3 pieces bottom and top on a reload.

 

[Poindexter]

I haven't read this yet. I am in the spring time chores here, we are having enough melt activity to have my undivided attention. I will fool with this autumn 2022. I have, in the past, been using a lot less than 3-5 pounds of kindling.

I do have a scale and I am going to fool with weighed amounts of kindling and a stop watch, but it will be Oct 22 before I have data.

 

[stoveliker]

I haven't read this yet. I am in the spring time chores here, we are having enough melt activity to have my undivided attention. I will fool with this autumn 2022. I have, in the past, been using a lot less than 3-5 pounds of kindling.

I do have a scale and I am going to fool with weighed amounts of kindling and a stop watch, but it will be Oct 22 before I have data.

My imperfect memory mistook your experimentalist mindset in response to BKVP's post for you having stated you needed that much. I searched now, and here is the post I vaguely recollected. Post #34 in this thread.

Possible Small Chimney Fire - Need advice

@bholler , @begreen , is not 1000 degrees F flue gas temp pushing the upper limit of safety, even with modern pipe?

www.hearth.com

 

[Poindexter]

@stoveliker I do remember asking that. With 14 % MC fuel and a handful of kindling, even a hand full of shavings made with an old hand plane, I can have a box load of full sized fuel pushing 1000dF flue gas temp with the combustor probe not even a third of the way up the inactive zone, from there I -have been- riding the air control valve to limit the flue gas temp to 1000dF while waiting on the combustor to heat up.

I have been fooling here in the spring shoulder a little bit with taking the loading door to just cracked open sooner and loading door latched closed sooner. Now that I am in the melt, or spring thaw, my RH near the ground is near 100% and my previously dry as a bone fuel is sucking up every water molecule that gets within fifteen feet.

One thing I will do this summer, Lord willing, is get some of the small sacks from fast food joints, the ones sized for one burger and one order of fries, to see how much those weigh, average, loaded up with wood chips. Besides handplanes, I have an electric jointer and an electric planer. That should be enough paper and wood shavings to get from cold stove to a bunch of kindling on fire in a big hurry.

What I will be looking to do is a fast/legal cold start with enough remaining fuel to run in active for, I want two hours. The way the regulation is written, whether or not cold start time is part of one hour of stove operation is disputable. A citizen with some sense would argue that smoke coming out of the chimney during a cold start clearly indicates the stove is in operation, but an expensive government lawyer might could make a convincing argument to the contrary to an expensive government judge.

Now that @BKVP has given me 5# of kindling to play with, and both @bholler and @begreen have signed off on 2000 (intermittent) flue gas temps I will be "doing science" this fall.

With 5 pounds of kindling and 2000dF stack temp, I can probably get my combustor lit off in under 20 minutes, at least with fuel at 14-16% MC. I want enough fuel left in the firebox for the cat to run engaged for two hours so the lawyer in the fancy suit can pound salt trying to argue I did a cold start and a hot reload in the same 'hour of operation.'

I need to find some fuel near 20%MC this year so I can fiddle with cold starts on that too. 20% just doesn't light off the way 14% fuel does.

 

[ABMax24]

@stoveliker I do remember asking that. With 14 % MC fuel and a handful of kindling, even a hand full of shavings made with an old hand plane, I can have a box load of full sized fuel pushing 1000dF flue gas temp with the combustor probe not even a third of the way up the inactive zone, from there I -have been- riding the air control valve to limit the flue gas temp to 1000dF while waiting on the combustor to heat up.

I have been fooling here in the spring shoulder a little bit with taking the loading door to just cracked open sooner and loading door latched closed sooner. Now that I am in the melt, or spring thaw, my RH near the ground is near 100% and my previously dry as a bone fuel is sucking up every water molecule that gets within fifteen feet.

One thing I will do this summer, Lord willing, is get some of the small sacks from fast food joints, the ones sized for one burger and one order of fries, to see how much those weigh, average, loaded up with wood chips. Besides handplanes, I have an electric jointer and an electric planer. That should be enough paper and wood shavings to get from cold stove to a bunch of kindling on fire in a big hurry.

What I will be looking to do is a fast/legal cold start with enough remaining fuel to run in active for, I want two hours. The way the regulation is written, whether or not cold start time is part of one hour of stove operation is disputable. A citizen with some sense would argue that smoke coming out of the chimney during a cold start clearly indicates the stove is in operation, but an expensive government lawyer might could make a convincing argument to the contrary to an expensive government judge.

Now that @BKVP has given me 5# of kindling to play with, and both @bholler and @begreen have signed off on 2000 (intermittent) flue gas temps I will be "doing science" this fall.

With 5 pounds of kindling and 2000dF stack temp, I can probably get my combustor lit off in under 20 minutes, at least with fuel at 14-16% MC. I want enough fuel left in the firebox for the cat to run engaged for two hours so the lawyer in the fancy suit can pound salt trying to argue I did a cold start and a hot reload in the same 'hour of operation.'

I need to find some fuel near 20%MC this year so I can fiddle with cold starts on that too. 20% just doesn't light off the way 14% fuel does.

Please forgive my ignorance, but at 1000f flue temps would the catalyst not be hot enough to be lit? I know you say the combustor probe is not active, but is this because of the delay in the analog gauge? Could a digital probe be fitted to shorten the response time?

 

[Ashful]

My eyes show me, my top down starts with very little smoke and very fast start of secondary flames.

I have experimented a whole lot with top down for lighting off my burn pit, maybe 2 dozen times per year. Because there's no chimney, and because a very large fraction of what I'm burning is green yard waste (shrub trimmings, tree trimmings, pulled flowers, etc.), and because the dominant wind and slope of the hill into which it is set naturally sends that choking-thick smoke straight toward the one neighbor who prefers open windows to air conditioning, I am very sensitive to the amount of smoke I make there. I have found the top down is always the best way to reduce the amount of smoke I'm making.

It's easy to say the reasons for this are obvious, until you actually try to explain it to a non-believer, and then you'll find yourself caught in a few arguments that are not so easily sussed-out.

 

[Ashful]

With 5 pounds of kindling and 2000dF stack temp, I can probably get my combustor lit off in under 20 minutes, at least with fuel at 14-16% MC. I want enough fuel left in the firebox for the cat to run engaged for two hours so the lawyer in the fancy suit can pound salt trying to argue I did a cold start and a hot reload in the same 'hour of operation.'

My God Poindexter, how long do you normally wait before closing that bypass? I'm not pulling any heroic feats, and I am pretty certain that my red oak stacked uncovered for three years is no where near 14%-16%, but I'm easily closing the bypass at 20 minutes with nothing but a quarter of a SuperCedar and one 18-inch 2x4 split in half over it, on full loads of this semi-dry oak. Why do you have to go to such extreme measures for this?

If the chimney hits 600F, I close the bypass, no matter what the stupid combustor probe reads. It's usually glowing within 10-20 seconds, easily indicating 1000F+, even though that nearly-useless (for startup) cat probe is still in the middle of the "Inactive" region.

 

[Ashful]

Please forgive my ignorance, but at 1000f flue temps would the catalyst not be hot enough to be lit? I know you say the combustor probe is not active, but is this because of the delay in the analog gauge? Could a digital probe be fitted to shorten the response time?

Yes. Poindexter's a smart guy, so he surely has good reasons for what he's doing, but I've never had a failed light-off at any flue probe > 600F, despite the reading on the cat probe.

That probe does not tell you the temperature of the cat, guys! It tells you the average of cat temperature over the last 10 minutes. When exhaust temp is ramping at more than 50 dF per minute, that probe just can't keep up. I think BKVP once said, "the cat probe tells you the temperature that cat was running 5 minutes ago," in rough agreement with my moving average over any 10 minute window.

 

[stoveliker]

Please forgive my ignorance, but at 1000f flue temps would the catalyst not be hot enough to be lit? I know you say the combustor probe is not active, but is this because of the delay in the analog gauge? Could a digital probe be fitted to shorten the response time?

Or at least, would heat up far quicker when the bypass is closed than it would gunk up from stuff before being hot enough. (For a metal cat, that is.)

I think that that is what's behind the fact I have had it glowing in 5 seconds after closing the bypass in 10 minutes after a cold start (experimenting with closing the bypass way before the gauge would be active, by measuring there with a thermocouple). I think the small thermal mass of a metal cat has advantages here.

 

[BKVP]

This letter was posted on the Alliance for Green Heat's FB page. I thought it was worth sharing here. It brings up very good points. It's often not the stoves, but the fuel, draft, and how the stoves are run.

Letter: Ways to clean up wood burning

The trouble is, laboratory testing and real world operation are two different situations

www.cowichanvalleycitizen.com

He's got a few things mixed up. The EPA emission standard for crib fuel (M28R) is not 2.5, it is 2.0 gr/h. The 2.5 gr/h standards is for cord wood testing, which is an ATM granted by EPA, based upon ASTM3053. Also, it is not necessarily 2" x 4"'s in M28R. Depending upon FBV, you could wind up with an entire load of 4" x 4".

As for loading on hot coals, all stoves are different. Employed technologies respond differently to different loading practices. The article is just a tad bit too generic for an industry with so many different stove designs.

 

[BKVP]

They shouldn't be running that hot at all normally. 900 is the absolute top of what I like to see. Typical cruising temps are 450 or 500 internal temps which normally keeps you just above the condensation point at the top of the chimney. If the chimney is really well insulated you can run lower. If it's exterior clay or an air cooled chimney possibly a bit higher. It doesn't matter what stove it is those are the temps required to avoid creosote buildup. But no 600 to 900 is not stressing any of the metal excessively. Just wasting heat

And of course, stack temps are highly variable depending upon technology of the stove itself.

 

[BKVP]

For me a good top down fire is 1/4 to 1/3 of the firebox full clear to the top of kindling. At a small fire starter light close the door. Reload in 2-6 hours.

Absolutely think top down is cleaner but have no data. You can get the secondary combustion rolling in 5 minutes. No the stove is not up to temp yet on a cold start but it gets there quickly. On a reload I always start with 3 pieces of kindling on the coals and another two right on top to kick that secondary combustion off ASAP.

My first thought on your picture was there is not enough wood and kindling in that load. Is getting warm out so I understand if that a smaller load but the fewer times you add wood the less smoke goes out the stack unburned.

So some very loose data exits on fuel loading orientation and how it effects emissions. A representative from a state agency has been loading fuel in multiple stoves. Baseline data was gathered based upon loading per the Owners/Operators manuals that came with the stoves. Thus far, EW loading has had the highest level of PM, followed by NS loading. In fact, the cleanest across all stoves used was cross stacking layers of fuel.

I expect this data to be available before years' end when presented to EPA.

 

[BKVP]

I believe that I read that @Poindexter uses a few pounds (3 or 5) of kindling to get up to (cat) temperature quickly. I don't use that much either (and can get my cat engaged in 5-10 minutes -- I know cat temps are different than secondary burn temps, and thus a comparison with the discussion here is not very meaningful but: )

I think a lot of this depends on ones definition of kindling, ones flue set up, ones stove, and the dryness of wood and kindling (and the weather, tightness of the home etc etc).

It's nevertheless good to read how others do things well. Try things out for yourself, and stick with what has the best results in your situation.

All good here, but it also is highly dependent upon the technology of the appliance. It's far easier (I mean to say quicker) to get to 550F than 1150F.

 

[BKVP]

My God Poindexter, how long do you normally wait before closing that bypass? I'm not pulling any heroic feats, and I am pretty certain that my red oak stacked uncovered for three years is no where near 14%-16%, but I'm easily closing the bypass at 20 minutes with nothing but a quarter of a SuperCedar and one 18-inch 2x4 split in half over it, on full loads of this semi-dry oak. Why do you have to go to such extreme measures for this?

If the chimney hits 600F, I close the bypass, no matter what the stupid combustor probe reads. It's usually glowing within 10-20 seconds, easily indicating 1000F+, even though that nearly-useless (for startup) cat probe is still in the middle of the "Inactive" region.

They have enforcement officers driving around issuing NOV's (notice of violation) for opacity violations. Fairbanks residents have to get up to temp quickly and do so with as little smoke as possible. I'll bet you there are more Ringelman charts in FNSB than the rest of the USA! And for all those with bypass operations in their stoves, that also employ a combustor, if your fuel is well seasoned (14%-24%) you can close the bypass and see a more rapid increase to "active". I know this because I am finally (thank the Lord above) out of hardwoods and now into my 5 year old Tamarack! We tested a bunch of my fuel from home here in the lab. Using 2" probes, it ranges between 9%-10% MC.

 

[john26]

I have started a top down procedure similar to Poindexter. I fill my firebox with a 3/4 load usually red oak larger splits on bottom smaller on top. I then place 1 sheet of news paper, store add or part of a brown paper sack folded up on top with wood chips and sweepings from my wood pile folded inside. After lighting the paper and having a strong fire I start cutting back the air, closing the boost air and bypass damper by visually watching the smoke in the fire box until it disappears. This seems to minimize smoke on start up. I follow this all 3 of my tube stoves my PE and Napoleon have little smoke on start up and almost non was up to temp the Ashley furnace is another story but I am working to minimalize that as well.

 

[Poindexter]

I have posted a few times before about this frame of reference.

My stopwatch, the clock I have to beat, is based on observing stack plume opacity, not observing what color the combustor is glowing.

The smog police on the street in front of my house don't care what color my combustor is glowing, or where in the active range the probe is pointing; they are sitting out there on the street, with no warrant required, observing my stack plume.

Having a glowing engaged combustor does not immediately a clean plume make.

I have fiddled with early engagement - a little bit- a few years ago and found (with a small data set) that engaging early actually increased my total time to clean plume. What I need, to not get a ticket, is a short time to clean plume.

It does seem like if/when my flue gas probe 28" above the stove collar hits +1400 degrees F I should have a good secondary burn going on in the chimney pipe, and possibly a clean plume to go with it. This is, today, a hypothesis with no supporting data.

 

[stoveliker]

Yes, but a hot combustor (and glowing is a good and easy measurement that it's hot) is needed for a clean plume. So the earlier the combustor is hot, the earlier the plume is clean (even if those times are not coincident). In particular because I believe that BKs are not designed with "clean burn with the bypass open" in mind. I.e. trying to go as quick as possible to a clean plume by burning in a way the stove was not meant to be clean, seems a bit strange to most of us (dare I say).

But, you have done the experiment, and I should not doubt actual data....

 

[Ashful]

Having a glowing engaged combustor does not immediately a clean plume make.

Like I said before, "Poindexter's a smart guy, so he surely has good reasons for what he's doing." I have to admit, it's probably been more than 5 years since I intentionally looked up at my chimney to see if smoke is coming out of it. Sometimes I notice it when I'm outside, and most of the time it's clear or nearly so, but I'm sure it's not in the early part of a burn cycle, when I'm still indoors getting dressed and waiting out the 20 minutes on high after closing that bypass.

But you live in a place with different rules, and I suppose they're rules that could come to most of us someday, so this is good information to log for future use.

Any chance of getting involved with the municipal government, and getting the regulation modified? Is clear plume really the best measure against the problem they're trying to manage, or just the easiest thing to police?

 

[BKVP]

Like I said before, "Poindexter's a smart guy, so he surely has good reasons for what he's doing." I have to admit, it's probably been more than 5 years since I intentionally looked up at my chimney to see if smoke is coming out of it. Sometimes I notice it when I'm outside, and most of the time it's clear or nearly so, but I'm sure it's not in the early part of a burn cycle, when I'm still indoors getting dressed and waiting out the 20 minutes on high after closing that bypass.

But you live in a place with different rules, and I suppose they're rules that could come to most of us someday, so this is good information to log for future use.

Any chance of getting involved with the municipal government, and getting the regulation modified? Is clear plume really the best measure against the problem they're trying to manage, or just the easiest thing to police?

Boy that would be nearly impossible. Designated by EPA as serious nonattainment, brings a host of serious consequences. In addition to the opacity regulation, Alaska Department of Environmental Conservation (ADEC) has also put into place, an approved by EPA, many new requirements. Purchasers of wood or pellet heaters must register their appliance at the time of purchase. Wood sellers must be licensed and have the wood tested in order to sell it. The sellers themselves must be registered with the state. Any wood or pellet stove more than 25 years of age cannot be used. Non EPA certified wood heaters must be removed at the time of sale of the property. So if you purchased, in 2014 or earlier, a legal to sell/purchase fireplace, had $20,000 in stone work done, with a total investment of say $40,000, it must be removed at the time of sale.

Currently ADEC will give you $10,000 to surrender ANY installed and operating wood or pellet heater, to be used for oil, gas (LP/NG) or electric heater. The caveat, that same home can NEVER have any solid fuel heater installed....EVER. Try and sell a home in a part of the world where winter temps drop below 0 most of the entire, long duration winter.

Also, for those of you still reading this, ADEC has created the "approved" list of solid fuel heaters. ADEC has implemented their own metrics to disqualify wood heaters. As of December of 2022, they way it is currently, of the 157 certificates issued by EPA, only 6 will remain.

So.......here's the rub, so to speak, two programs in the lower 48 states, now allow only wood or pellet heaters on the Alaska list. One near Bellingham WA, which is a low income grant for changeouts, the other in Oakridge Oregon, a $2M EPA funded changeout.

The most difficult metric employed by ADEC, is what is termed, the first hour filter pull. In 2015, when EPA updated the NSPS, the test methods, both M28R and ASTM 3053, require us to pull the filter after the first hour. ADEC, without any data whatsoever to support their decision, submitted to EPA in their SERIOUS SIP, the elimination of any solid fuel heater that showed 6.0 g/h or more on the first hour filter pull. The absurdity of this is a heater that has an EPA weighted average of .8 g/h overall, some even cleaner, are automatically removed from the list.

Hey, there is an air quality issue that is serious in FNSB. Poindexter and thousands of others deserve and need clean air. But grabbing at low hanging fruit will not fix the bigger issue of air quality.

Poindexter can share the methods used and cost of electricity in FNSB. He can speak to the lack of infrastructure and source of NG, but then there's heating oil, probably originating in guess where....and the fact they shut down the refinery they had to created their own oil/fuel, which is from their own state.

Go Poindexter....correct my errors and let folks know why they need to check their stacks.....

 

[Poindexter]

I can review the over the summer if the markets settle down. New to my local market since I last did all the math is Natural Gas arriving in Anchorage by ship and then getting to Fairbanks by either truck or train.

3-5 years ago, a bushel basket full of cordwood cost one dollar. The same number of BTUs, the same bushel basket, as #2 fuel for my boiler, two dollars. The same amount of energy as electricity, ten dollars.

Since then the wood sellers have figured out they can make more money by looking at the price of oil when pricing their cords, and are up around $1.80 for their bushel basket relative to two dollar oil.

I (the household) use, total, electricity, fuel oil and cordwood, close to 300 million BTUs per year. About 250 million of those, 5/6, is strictly for heat. House is nominal 2400 sqft, 1200 up and 1200 down.

I got all but one cord of my wood for winter 22/23 delivered in Feb 22. I think I spent about $330/cord (multiple vendors) for green splits dumped in my driveway. At 18 MBTU per cord for white spruce and fuel oil (now mandated to be the cleaner burning #1, with fewer BTUs per gallon) at $3.4x/gal delivered into my tank I will be saving about $143 on the oil bill for every cord of wood I burn. Then in late Feb oil prices went up. There was at the same time a radio ad by the gas company touting natural gas as "30% cheaper than fuel oil."

Hopefully the availability of natural gas will put some downward price pressure on cord wood.

There were two refineries in North Pole, Alaska, just down the road from my house about 20 miles. The smaller one operated by PetroStar is still open topping diesel and heating oil out of the crude pipeline, then putting the remainder (heavier) fractions back into the pipeline. There was a larger topping plant, operated by Flint Hills, that has shut down and been disassembled. Neither of these two plants had a cracking tower, neither can break long chain hydrocarbons down into smaller chemicals like gasoline or diesel. As topping plants they heat up the crude and recover the naturally occuring diesel sized molecules.

I think I read in the paper that Flint Hills pulled out because they couldn't make any money at the price per bbl the state of Alaska was requiring for crude oil out of the pipeline.

The Air Quality side does not have an easy answer. Fairbanks, similar to Los Angeles, is surrounded on 3 sides by hills, and we get inversion layers. When we have a lense of cold air trapped against the ground it might be 30 miles in diameter but only 100 feet thick.

All of the emissions from everything are trapped inside the inversion layer. Trucks, cars, woodstoves, oil fired boilers, locomotives, planes at the airport, powerplants, all trapped. Drive up one of the hills surrounding town, gain 100 feet of elevation, and you can literally see the inversion layer trapped on the ground against the city.

As a realist, buying a lot of BTUs, it makes sense to be price sensitive for the BTUs I buy. As a grownup it makes sense to me to run my woodstove efficiently both for best heat recovery and minimal pollution. As an idealist, I prefer to be as close to carbon neutral as possible, so wood again rather than fossil fuels.

I honestly don't see EPA air quality guidelines getting met in Fairbanks year after year unless about half the population moves away to somewhere else.

One thing that bugs me is having to shut down during AQ alerts - and then do another cold start. I don't really know how many grams of what come out of my stack when I do a reload on a bed of hot coals. When my stove is raging I can be done with the charring phase before I get the loading door shut, and can re-engage the active combustor as fast as I can move my hand between the levers.

Do I get a brief spike of crud doing a hot reload? I am sure I do. But the time of the spike, the duration, is seconds, like 30-40 seconds from disengaging the combustor, fill the fire box, re-engage the combustor.

I think a hot reload has to be less total crud out of the stack compared to a cold start. Just by looking at how much fuel is left in the firebox when the combustor gets engaged. I can routinely burn something like a quarter of the fuel in the box during a cold start getting to combustor engagement. On a raging hot reload I would estimate something like 1-3% of the fuel load getting consumed before the combustor is re-engaged. I guess I would need a scale under each of the four legs of my stove to quantify that.

I need to get some chores done today. Haven't read the article yet.

 

[snobuilder]

Why does a seasonal pollution problem in Fairbanks lead to a confiscatory nazi like control of wood stoves throughout the entire sparsely populated and enormous state of AK. That is a tyrannical over reach even by a commy country let alone a US state.

 

[begreen]

It's unlikely that the rest of the country will be as extreme. They are not driving the rules for everyone. AK and NYS pointed out flaws in the testing, but not the stoves. Fairbank's rules do not apply to the rest of the country. You are mixing up regional rules (not EPA) with stove requirements.

Still, there are many parts of the country that have the same geographical constraints and are prone to temperature inversions. Clean burning stoves help make a dent in emission while using less wood. More complete combustion also means fewer gases emitted, including CO2.

 

[snobuilder]

It's unlikely that the rest of the country will be as extreme. They are not driving the rules for everyone. AK and NYS pointed out flaws in the testing, but not the stoves. Fairbank's rules do not apply to the rest of the country. You are mixing up regional rules (not EPA) with stove requirements.

Still, there are many parts of the country that have the same geographical constraints and are prone to temperature inversions. Clean burning stoves help make a dent in emission while using less wood. More complete combustion also means fewer gases emitted, including CO2.

Where did I mention the rest of the country? But you do bring up another concern as the progressive side of central government control always starts relatively small and regional and then gets moved into the national realm while no one is looking.

Clearly the seasonal Fairbanks issue shouldn't be applied to the entire state.

 

[Poindexter]

I peeked at the article, and it was short. Pacific Energy is a well known brand with a deserved good reputation. They are often suggested here, and are carried by my local BK dealer as his second line stove. If they were no good, my local dealer would have some other brand on the floor.

I do not see a footnote for this statement: "Those same stoves that achieved PM 2.5 g/hr in the lab are actually averaging closer to PM 7.5 g/hr in the real world. " It turns out this is not a lengthy scholarly article, but rather a letter to a newspaper editor.

Wet wood we all know is a bad thing.

The "fuel above the flame" idea clearly has some merit, as born out by the experiences of begreen and Ashful in this thread. In a raging hot stove with plentiful hot coals and a catalytic combustor I am not sure it matters. For a cold start, I can see lighting top down could result lower total emissions on average during the start up phase in some stoves.

I think in sections two and three the author is talking about non-catalytic stoves in general. I do not miss my old EPA non cat stove at all.

What I have been doing is lighting my cold stove at the bottom front right corner- my loading door latch is on the right. Once my fire is caught, closing the loading door to just cracked encourages the burn to spread across the front face of the fuel load, and then latching the door so the air is coming down the airwash encourages the burn to proceed front to back.

My main observation about my Ashford 30 is it has a lot of mass, and a lot of momentum once it is up and running. Cold starts burn a lot of fuel. Keeping the stove hot with regular reloading means I am not wasting fuel heating that big of lump of metal back up before the combustor can be re-engaged.