Why am I re-loading every hour or so?

[joefrompa]

Hi all,

Asking this from another thread. Been burning for about 3 months now, and I'm using an "appropriate" amount of wood for the outside temperature, the size of my stove and burn pattern, and what I've read on here. Probably .75 cords per month, or roughly 4 cubic feet per day with some "off" days.

This is my first year burning and I've got alot of ash and pine. Lets assume I've got a mix of decently seasoned, semi-seasoned, and semi-unseasoned wood. I can easily get my stove top temp up to 600-700 degrees with great secondaries, provided I build a nice fire and then stock it full of whatever medium splits I want. I can do this with my flue damper SHUT and the air control about 50-60% open.

Nonetheless, I try to keep my stove about 450-600 for good heat output. On any given day, I'll have a good established fire going. 1-2" of ash bed, good bed of coals. Fire goes down to maybe 400 degrees and it's mostly just coals, so I re-load the box about 2/3rds full (remembering it's got a coal bed and ash bed, so 2/3rds of whats remaining).

The air control is maybe 50% open during the time, flue damper is shut. The wood lights up within 30 seconds to 5 minutes and progresses to "full blaze" within 5-15 minutes. The heat goes up 100-150 degrees and i'm getting good solid heat output. I might tap the air shut a little more, but if I go down to say 25-30% open the fire will start to shut down and the heat output will drop(either a good design by Lopi, allowing me great fire control, or a weaker draft, or both).

That 2/3rds load will burn down to mostly coals within 60-75 minutes, the stove top will drop down to 400 degrees or so, and it'll be time to reload. If I LEAVE it, it'll cool down to 350 or even 300 within another hour. Coals will be visible for 4-6 hours, at which point they stop being visible and its straight ash.

If I stock the firebox full, I have no real visible coals after 8 hours even with air control shut down to 25% overnight, but I will have serious coals under the ash. If I poke those coals out a bit, I can get medium splits to light off of them.

According to some on here, reloading every 60-75 minutes is crazy talk. But everything I'm doing seems right, sounds right, the heat output is there, the secondaries are there, and I've learned the air control a good amount. So what am I missing?

 

[madrone]

What's your chimney like? I have no experience with a flue damper, and have to wonder why you've got one installed. Sounds like either low draft or under-seasoned wood. 15-20 minutes into a reload, I usually can shut the air down to nearly shut (25% or less) and still have raging secondaries and plenty of heat. 3-4 hours is about as short a burn as I get when I'm heating up the house in the morning. Pine doesn't last long, but that's way too short. I've found coals under the ash after 12 hours with Doug Fir.

I'm going to have to buy a damn thermometer.

 

[madrone]

Shot in the dark here, but if your flue damper is shut does that mean the draft is restricted? Could it be that you have insufficient draft to really keep secondary air flow through the tubes? If so, opening the damper and closing the primary might result in higher efficiency.
Like I said, no experience with a flue damper.

 

[rdust]

You're not going to have active secondary flames for the full burn,(just a couple/few hours) you still have a lot of heat in those coals when you're reloading I bet. I usually do not reload till my stove top is down to 200-300, I let the coals burn down to a manageable amount. If I'm around and the active flame is gone I'll open the air up to allow the coals to burn hotter.

 

[budman]

Is he talking about a flue damper or the bypass.

 

[oldspark]

Madrone has the right idea, close the primary air and just use the damper if you have too strong a draft, usually you do not need a damper on a EPA stove.

 

[branchburner]

Lets assume I've got a mix of decently seasoned, semi-seasoned, and semi-unseasoned wood.

That 2/3rds load will burn down to mostly coals within 60-75 minutes, the stove top will drop down to 400 degrees or so, and it'll be time to reload.

You may have high expectations of always getting max heat output from this stove given the wood is not ideal. I don't really like the sound of that mix - it sounds more bad than good. I burn some pine, and if it's not dry I find it needs a lot of air to burn well, but then it burns very fast. If it's bone dry, I can close the air and really maximize the length of the burn and heat output.

Burning in a full cycle means some periods where temps may drop a bit, but only getting an hour or two of quality burn time says to me "too much air". I agree with others, you should give it a try with less air and forget the damper. Maybe experiment with some of your best/dryest wood and see how much of a factor it is.

Every time you reload, you are losing a lot of heat up the flue, even though it is giving you good stove temps. Remember, stove temps do not equal heat. Your overall heat output may be as good, or better, if you reload less often and accept some lower temps for a longer part of the burn cycle (assuming your wood is dry enough). When I burn at 50% air open (vs my usual 25% or less) my stove temps may be higher, but so are my flue temps. In addition to going through the wood faster, I'm pushing more heat up the flue than I should be.

Are you checking flue temps at all?

 

[shawneyboy]

Although I do not own that specific stove, as others have said, the flue damper most likely isn't needed. By closing flue damper and opening air control you are directing more air to the wood itself than to the secondaries. This in and of itself may, note I say may, be causing the accelerated burn and lower efficencies. Open up the flue damper, close down the primary controls. This will direct more air to the secondaries and should, increase effeciencies while increasing burn times.

All wood is not created equal, and with your "mix" of wood I am sure that is part of the issue also.

That being said, I would start with the "open flue/ close primary" and see if that helps, then go from there.

Shawn

 

[NH_Wood]

+1 to Oldspark and Shawneyboy. The pipe damper should be last resort. Keep wide open unless needed and control your fire with the primary. I also agree that you can't expect to have constant high temps with a wood stove - these EPA stoves are good at cycling. Full load, to high heat, to coaling stage, to lower heat, to coals, to reload. If you want to have high heat sooner, you need to load sooner. A good way to do this is to reduce the coal bed sooner. If I have real cold temps outside, as soon as the secondaries are done, I open the primary air and start to burn down the coals sooner. By the time the stove hits 300*, I can usually rake the coals and add a full load. Keeping the primary shut will results in reaching 300* with a large coal bed, and THEN having to burn down the coals to maximize the size of load. By that time, I would have been wanting more heat. Good luck! Cheers!

 

[madrone]

Is he talking about a flue damper or the bypass.

Good point! If you're talking about the bypass, then DON'T open it wide and shut the air down. The bypass is not a flue damper. It should only be used during loading.

I'm leaning towards under-seasoned wood requiring more air, which is sending more heat up the flue and shortening the burn cycle.

 

[thewoodlands]

You're not going to have active secondary flames for the full burn,(just a couple/few hours) you still have a lot of heat in those coals when you're reloading I bet. I usually do not reload till my stove top is down to 200-300, I let the coals burn down to a manageable amount. If I'm around and the active flame is gone I'll open the air up to allow the coals to burn hotter.

+1 on what rdust talks about on reloading.


zap

 

[oldspark]

Is he talking about a flue damper or the bypass.

Good point! If you're talking about the bypass, then DON'T open it wide and shut the air down. The bypass is not a flue damper. It should only be used during loading.

I'm leaning towards under-seasoned wood requiring more air, which is sending more heat up the flue and shortening the burn cycle.

Forgot about the bypass dealy bob on the lopi, we need to make sure what he is talking about.

 

[Seasoned Oak]

Reloading every hour or so? Sounds like a fulltime job. I guess im spoiled with my top loader ,i can filler right up to the top and go all day, the burn time is directly linked to the air adjustment. ON low 2 loads in 24 hour period .on high settings still never more than 3

 

[joefrompa]

All,

Very sorry for the confusion. I have a bypass damper that allows me to control whether the air goes straight up the flue or circles through the burn tubes before going up.

I do NOT have a seperate flue damper. Whenever my temp is above 200 degrees stove top, I leave my bypass damper SHUT (forcing the air through the burn tubes) unless I'm reloading.

I have never seen my active secondaries sustain for more than 30-45 minutes straight - that's with stove top temp at 650-700, a load of good wood in there, etc. - and the air control is usually 30-40% at that heat range.

Let me be very clear - if I shut the air control further, the fire DIES. I will lose 100 degrees in 10 minutes off stove top (yes, the blower is still on, but it shows how much the fire stops outputting heat).

Also, my stove is great at heating about 400-500 square feet. However, the rooms directly adjacent to that 400-500 square feet are cool, as in 62-64 degrees even when the stove's been at 450-600 for 3-4 hours straight and blowing strong. So yes, I try to "push it" to maintain high heat output. I can tell a notable drop in heat output when the stove top gets below 400. Even at 300-350, the main room starts to cool off notably.

Joe

P.s. I have a ~13-15' exterior chimney with a straight-up insulated 6" liner. My draft appears poor because I HAVE to leave the door cracked for the first 10 minutes after a fresh light up, or else the fire will simply smolder. Also, I've had some nasty backdrafts during cold light-ups where my whole 1200 square foot first floor filled with smoke.

 

[bpm44]

I have the Lopi Revere insert which is pretty much the same as yours, and it sounds like all of the advice above is on target. I think it is the wood species you are burning and that you are still learning the stove. I used to have a Patriot (small Lopi freestanding stove) at our old house and have noticed that there less what I would call "usable heat" with the insert versus the freestanding i.e. it would run you out of the room if you pushed it whereas the insert keeps everything comfy but doesn't run you out. Yes, this house is bigger, but so is the insert, it is a bigger stove, has a longer burn cycle and the heat is not as "spikey". Lots of variables. That being said, my insert burns great, keeps the house plenty warm (2000 sq ft ranch - 70 to 72 degrees with a couple small entree air fans blowing cool air back towards the stove for the back two bedrooms) and my reload times are considerably longer than yours but do vary depending on what the previous load was in terms of size of splits, species, if I was looking for max heat of just keeping a fire going, etc. I am burning my usual mix of maple, oak, ash, hickory, boxelder, hophorn beam and cherry that was all split by me 2 years ago. I second Post#6 by branchburner. Typically when I'm home I load my stove with my wood as you have described in your post and let mine run up to about 600 or so with the primary open about 75% and then shut down the primary in increments. My insert will run up to 700 - 725 during this process and then come down and settle in at about 600 - 625 with the primary only open about 15%. Secondaries roll nicely with every load cycle, but only last a couple hours out of each cycle. If its real cold out I do as NW Wood does in Post#8. to burn coals down quicker and make more room inside the stove. My suggestion would be to try and trade or buy enough of some wood that is really seasoned and a denser species than what you have so that you can compare the difference. I know that is easier said than done, but there's probably someone from Hearth.com reasonably close to you that would help you out. Also try shutting your air down more incrementally. Mine has really good responsiveness to the air control as well and can snuff the fire right down if I'm inpatient. I've been burning for 20 years and am still learning this new stove which, like yours is 3 months old. You'll get the hang of it. EPA stoves like to cycle more than the old smoke dragons and little things do make a difference with each stove and the differing installations. It also helps to have your own seasoned wood, wether you buy lengths to buck and split, or scrounge, or just buy cut-split-delivered a year in advance. When we moved I sold about 3 full cords to the buyers of our old house to fund paying a friend with a Tree Biz and dump trailer to haul the other 7 cords to our new (to us) house. Don't get discouraged that your burn times aren't real long just yet - a couple years from now you'll look back on your first year burning and see how far you've come. Strive for good wood and burn habits. Hope this helped a bit and sorry to ramble. I usually don't post much - I'm a slow typer, not too good with a computer and had to have my wife re-set up my access to hearth.com after we moved, and she changed my screen name too - now it matches with the other boards I check! Stay warm!

 

[Wood Duck]

Remember, stove temps do not equal heat. Your overall heat output may be as good, or better, if you reload less often and accept some lower temps for a longer part of the burn cycle (assuming your wood is dry enough). When I burn at 50% air open (vs my usual 25% or less) my stove temps may be higher, but so are my flue temps. In addition to going through the wood faster, I'm pushing more heat up the flue than I should be.

Are you checking flue temps at all?

How is it that stove top temps are not the same as heat output? The only way heat gets fom the firebox to the room is through the steel of the stove, whether the stove radiates heat or is a 'convective' system (which still requires the radiation of heat from steel to air). The hotter the steel, the more heat is transferred, so stove top temperature (assuming higher stove top temperature always corresponds to higher temperature on other parts of the outside of the stove) should be an indicator of how much heat is moving from the stove to the room. I understand that there are ways to have a higher stove top temperature but lower efficiency by losing too much heat up the flue, but is there a way that higher stove top temperature would not indicate more heat output into the room?

 

[rdust]

You chimney is about the minimum that you should have. Can you add another 3' section to the top to see if it helps?

Tell us more about your wood, how long has it been cut/split/stacked?

Also how well is the house insulated? If temp is dropping fast once the stove gets around 400 you may want to address that at some point.

 

[madrone]

I'm guessing this is a good, old-fashioned combination of chimney a little too short and wood a little too wet.

 

[joefrompa]

Wouldn't a bigger chimney simply be adding more air (draft) to the process? How would that help slow down my burn times?

My wood is 30% pine cut and split this summer but not ideally stacked, 50% ash lain dead for over a year, bucked for 2 months, and then split in September, and then 20% ironwood from an 8" round tree lain dead for 3 years and split in August.

Yes, it's not ideal.

Jeeper I shut my air down as follows:

Full open until fire is roughly 350-400 and blazing well (usually about 15 minutes from a cold start)
Shut down to 60% until fire is at 450-500 and still going well
Shut down to 50% once fire has reached 500 - around this time, I'm usually getting good secondaries
If fire is still rising in temp, it goes down to 40% and usually secondaries increase and flames coming from the logs start to decrease

Now, up to this point, if I shut the air faster it'll almost always start smoldering/dying.

If the fire continues up to 600-700 degrees, I'll go down as far as 30%. I've NEVER been able to go below 30%, even gently nudged there, without having the fire shutdown within 20-30 seconds.

I assumed that Lopi built in a very TIGHT air control allowing you to shut down the fire if needed, or to account for people with much stronger drafts...

 

[oldspark]

Not a bigger chimney, a longer one, higher in the sky type, makes for a better draft, 15 ft is the minimum length for a EPA stove.

 

[rdust]

I've noticed something of interest on my Endeavor which may also apply to your stove. My primary air is closed before the air control lever is pushed all the way in. I noticed this while pushing the air control in while watching the primary air intake at the bottom of the stove. I only mention it since it may be getting closed down more than you think.

 

[branchburner]

The hotter the steel, the more heat is transferred, so stove top temperature (assuming higher stove top temperature always corresponds to higher temperature on other parts of the outside of the stove) should be an indicator of how much heat is moving from the stove to the room. I understand that there are ways to have a higher stove top temperature but lower efficiency by losing too much heat up the flue, but is there a way that higher stove top temperature would not indicate more heat output into the room?

I don't assume this. My experience: with full open air and bypass open, I get a very hot top surface and a very hot flue (700F and 1000F), but the back of my stove (where burn chamber is) stays about 200F. When things are cruising, my top is 500F, back is 600F, and flue is only 300F.

 

[madrone]

Wouldn't a bigger chimney simply be adding more air (draft) to the process? How would that help slow down my burn times?

It would allow you to close the primary farther, directing more air to the secondary system. That'll keep more heat in the stove instead of sending it up the flue. It takes a decent draft to pull enough air through those tubes. Your set up might be sufficient though, because your wood sounds suspicious. I'd buy a couple of armloads of grocery store firewood and see if that stuff will stay lit with the air closed further. That would rule out your chimney.

 

[bpm44]

Sounds like you have the incremental shutdown going on. I run my temps a bit higher than you which may be due to wood species and or draft characteristics of my chimney vs. yours - mine just seems to run best at those temps. I have noted over the years of hanging out here that the Lopi users *seem* to have higher stove top temps than with some of the other brands. Keep working at the suggestions given and keep us updated. Good Luck and Happy Burning!

 

[joefrompa]

So far tonight I've loaded with some very dry small limbs (1-3" in diameter) of a fairly light wood and as soon as its "lit off" (showing a fair amount of flames), I shut the air down to 40% or so. In the past, that has killed it off....but tonight it led to really fast temperature spikes and tons of secondaries.

But the wood still burned down within 45 minutes