Ready to Join The Gang - Time For a Wood Stove!

[gregbesia]

How about wood bricks. I know a lot of people burn and like them . http://www.woodpellets.com/blog/wp-content/uploads/2014/05/WOODBRICKS1.jpg

 

[Ashful]

Still working on getting those overnight burns, but really struggling to hit much more than 5 hours now. It seems that by the time the stove is hot enough to choke the air down, the wood is already quite a bit burned away. And then once I finally get it down low enough, choking it completely off drops the temp to below the safe zone within an hour. Still struggling to find a balance!

I think the majority of the problem is simply he wood is just too damn wet.

Yes, what you describe above is classic wet wood performance. Too slow to get going, and then stalling after you do. I also fumbled my way thru my first year with this, as there was no way I was going to let anyone convince me to not burn my new stove the first year!

Taking a year off is the best and easiest solution, while your wood dries. But there are other solutions for the persistent. Mixing your half-seasoned wood with dry wood brick products is a popular choice for folks in your situation. Mixing your wood with lumber (pallets, cutoffs from lumber mills, etc.) is another. Most lumber ships around 8% MC.

 

[Log Splitter]

Yeah, I'm just going to have to let the stuff I have split another year. And make sure it's in a good spot so it actually gets some sun & air flow.

I'm going to get some firewood from this place around here that everyone speaks very highly of. I'll do a combination of that, plus a little bit of oil at night time. With oil as cheap as it is now, I won't feel as guilty

 

[Log Splitter]

I got the wood delivery I had previously mentioned. I decided to go with 1 cord seasoned (18-22%) and one cord kiln dried (8-12%).

This stuff is light years better than what I was using. I feel like I have great ingredients, but I still need to work on my recipe! I'm struggling to get these longer burn times.

For instance, last night, around 8:00 PM, I had a nice bed of coals left from my last fire. I decided to load the oven up with the kiln dried wood. I went north south as I feel I can best utilize the space available. I loaded it up to the max, and within just a few minutes, the oven was blazing! I let it go with the higher airflow for only 10 or so minutes until I choked it down halfway. Then 5 minutes later, I completely closed it off. The temperature kept rising, and even with the lowest airflow, was approaching the danger zone for temperature! Fortunately (also unfortunately) then fan for the insert 100% cools off the stove, so I turned the fan on, got the heat out into the room and the temperature stopped rising. It was still pretty high, but was no longer climbing.

Unfortunately, I was never able to get a lazy flame type of fire going. It was a roaring fire almost the whole 5 hours it was going I certainly did not get the 10 hour burn time I was hoping to get. Since it was so hot, the wood just burned down too quick. I did still have a nice coal bed 10 hours later, but the temperature was no longer above 350F, which is the lowest I like to let it get. When we're talking about "burn times" I would assume we mean the time the oven is running at a "house warming" temperature, right?

The door also turned foggy/black too which I was surprised to see, but I guess the ends of the wood were very close to the door. Any thoughts as to why this may have happened?

If anyone has any other suggestions on longer burn times, I'd love to hear it. E/W, mixing woods, larger splits etc. All I know is I don't think I'll go 100% kiln dried again. It was actually quite frightening when I opened the door. The sound of the flames was crazy!

 

[Squisher]

Sounds like you're doing pretty good. The key to avoiding the runaway hot fire is to cut your air back a bit sooner. Too soon can stall secondary combustion sometimes. So it's a combination of getting your insert up to temp so it has good secondary's but not letting your flue gasses get to out of hand. The more you heat the flue the stronger your draft is. The key is finding that sweet spot, so you're not to cool and not promoting secondary combustion, but not to hot so you run borderline overdraft and the load burns up fast.

But ten hours to coals is decent if the coals are still hot enough to throw full size splits on and you're off to the races again. Atleast for me with primarily softwood that's a good overnight burn.

 

[Log Splitter]

I'm actually running only on oak, hickory, maple and ash, so I'm surprised that my unit stops producing the needed heat after 4-5 hours.

Maybe I'm misunderstanding what "10 hour burn time" actually represents.

 

[Squisher]

Well certainly the heat is a cycle. It's not like it's going to be 600-700 stovetop temp for 10hrs. I usually build a buffer of heat in the house during the day for overnight. It seems like you're thinking it'll run kind of like a cat stove, just lower output and steady for longer. But it won't. The heat will peak and valley throughout the 'burn time'. I think most describe burn time as the time between loadings. And it's highly subjective, yes you can get a longer burn time if you let the stove cool down more and shorter if you're reloading hot.

I'd say just keep doing what you're doing and if you are finding it chilly overnight. Try to burn a little harder during the day to heat the house up more.

 

[Log Splitter]

Well certainly the heat is a cycle. It's not like it's going to be 600-700 stovetop temp for 10hrs. I usually build a buffer of heat in the house during the day for overnight. It seems like you're thinking it'll run kind of like a cat stove, just lower output and steady for longer. But it won't. The heat will peak and valley throughout the 'burn time'. I think most describe burn time as the time between loadings. And it's highly subjective, yes you can get a longer burn time if you let the stove cool down more and shorter if you're reloading hot.

I'd say just keep doing what you're doing and if you are finding it chilly overnight. Try to burn a little harder during the day to heat the house up more.

Good points. I suppose it is going to cycle if not tended to, which in nature, happens during the overnight burn.

I'll aim to really heat the house late evening, fully load on a smaller coal bed, and try to hit that sweet spot.

Any importance to E/W loading, or mixing the kiln & seasoned dried wood?

 

[brenndatomu]

Try loading N/S on the bottom then E/W on top of that...

 

[Ashful]

Any importance to E/W loading, or mixing the kiln & seasoned dried wood?

Air flow (which is into the firebox above the front door glass, on most stoves) will play games with the wood, when debating N/S vs. E/W. But for the most part, those looking at fireshow love E/W, and those using the stove as a heater relish N/S loading. When loading N/S, if your stove permits it, you can usually load the box fuller without concern for logs rolling against the glass (or out of the stove before you close the door).

Most EPA stoves like wood in that 15 - 20% range. Much drier, and the stove can go nuclear. Much wetter, and secondary combustion fails, or it becomes impossible to burn at a low rate (which can also lead to nuclear, when the wet wood finally dries, mid-burn).

Try loading N/S on the bottom then E/W on top of that...

Only if you like wasting space. The way most folks split, you're going to be able to pack it in tighter if you pick a direction, and stick with it.

 

[Squisher]

I've heard that e/w loading can slow things down a bit but I only load n/s, and I pack it tight as can be when I want a long burn.

Just as you said timing is everything. Time your overnight load just right and you've got much less of a temp dip overnight.

 

[begreen]

When doing a full reload on a hot coal bed don't go just by the clock. The air can be closed down fully in as little as 5 minutes with very dry wood especially if the draft is strong due to cold outside temps.

 

[Log Splitter]

What about wood size? If the volume of total wood is the same, does it matter how many total splits there are? Is it better to will larger splits burn longer, or is total volume the only thing that matters?

 

[begreen]

Larger splits will have less exposed surface area, they will burn slower. Load with large splits and use smaller splits as gap fillers if possible.

 

[Woody Stover]

I did still have a nice coal bed 10 hours later, but the temperature was no longer above 350F, which is the lowest I like to let it get. When we're talking about "burn times" I would assume we mean the time the oven is running at a "house warming" temperature, right?....I'm actually running only on oak, hickory, maple and ash, so I'm surprised that my unit stops producing the needed heat after 4-5 hours. Maybe I'm misunderstanding what "10 hour burn time" actually represents.......1200 sq ft

I'm claiming a 10-hr. burn time from my little 1.5 cu.ft. stove....on an average winter day here, and not too windy, I can get enough heat to hold at 70 or so when the stove top is 250+. I have to open up the air on the coals at the end of the burn to keep the stove above 250. 1000 sq.ft, insulation and air-sealing are marginal. If it were better, I wouldn't even need 250 to hold room temp. I realize that it's colder where you are but if a 3 cu.ft stove doesn't keep 1200 sq.ft. warm for more than 5 hrs, with a stove temp of 350, either your house is losing a ton of heat, or your definition of a "warm house" is a much higher temp than mine. The fact that you are referring to your heater as an "oven" implies that you expect to be baked...

Larger splits have less exposed surface area, they will burn slower. Load with large splits and use smaller splits as gap fillers if possible.

The larger splits should flatten out the peak-and-valley effect, extending higher heat output later into the load.

 

[Ashful]

What about wood size? If the volume of total wood is the same, does it matter how many total splits there are? Is it better to will larger splits burn longer, or is total volume the only thing that matters?

Total exposed surface area is the dominant factor in combustion rate and temperature. An equal volume of smaller splits has more surface area, and therefore will burn hotter and faster, supplied with adequate air. On stoves where it is not possible to shut down the air as far (eg. non-cat stoves), it can be tougher to limit the amount of air and maintain a controlled burn, if you stuff the stove full with toothpicks.

 

[Log Splitter]

I'm claiming a 10-hr. burn time from my little 1.5 cu.ft. stove....on an average winter day here, and not too windy, I can get enough heat to hold at 70 or so when the stove top is 250+. I have to open up the air on the coals at the end of the burn to keep the stove above 250. 1000 sq.ft, insulation and air-sealing are marginal. If it were better, I wouldn't even need 250 to hold room temp. I realize that it's colder where you are but if a 3 cu.ft stove doesn't keep 1200 sq.ft. warm for more than 5 hrs, with a stove temp of 350, either your house is losing a ton of heat, or your definition of a "warm house" is a much higher temp than mine. The fact that you are referring to your heater as an "oven" implies that you expect to be baked...
The larger splits should flatten out the peak-and-valley effect, extending higher heat output later into the load.

I cannot tell a lie, I certainly do like it warm! I've lived in Florida for the past 6 years, and I became accustomed to the heat.

However, with that said, I'm 70 degrees is warmer than I need it this time of year. I'm surprised to hear that your oven at only 250ish is able to keep your area heated to 70 degrees with marginal insulation.

I had a late night last night, so I loaded the oven up maybe 2/3rds around 3:00 AM. Seven hours later I still have a stove with many hot coals. I have to sift through a bit and bring the coals to the front along with open the airflow, but with that, the stove is running around 350 degrees. The blower is off now as it pretty quickly decreases the temperature once it's running.

The hallway in the raised ranch is 66, and the far end of the living room, the room with the stove, is running around 68.

Since writing this, I hit the fan on the stove, and we're now down to 300. Hoping it can hold steady there for a couple hours as the bed of coal volume is quite impressive.

So with that said, the house is by no means an ice box. I think maybe I just misunderstood "10 hour burn time". I keep forgetting that burning wood is not a binary action with an on/off, but more of a gradual progression from giant logs to smaller coals. 7 hours later from a partial load, I guess I should be happy with a 300 degree stove?

 

[Log Splitter]

And about 30-60 minutes later, it seems we're settling around 225-250 degrees with the fan on the lowest setting. Main room temperature hovering around 70 degrees, hallway 65+ and bedrooms at the end are low 60s.

From a few days ago, but both dogs now have found the heat. The little Boston fell in love day 1. Took the bigger Boston a few weeks to get comfortable

 

[Squisher]

Settling in around 225-250 seems cool to me. This is measured on the front of the insert correct? Do you have secondary combustion running at that temp? If you can't tell from the flames can you look outside and see if you have smoke exiting the chimney?

 

[Log Splitter]

Settling in around 225-250 seems cool to me. This is measured on the front of the insert correct? Do you have secondary combustion running at that temp? If you can't tell from the flames can you look outside and see if you have smoke exiting the chimney?

There's no smoke at this point as it's nothing more than a bed of coals. But yes, I certainly lose quite a bit once the fan is on. About 100 degrees it seems. I'm measuring temp on the face of the insert.

I just threw a decent size split on of super dry hardwood. Within 30 minutes we're back up to about 375 degrees with the fan on low.

 

[begreen]

Looking at the size of the fire and coal bed I have to agree, 250-200F seems low. Our T6 stove top would be more like 450-500F at that stage of the burn with the blower on.

 

[begreen]

Here is a shot of the fire, burning a load of doug fir and alder after 3 hrs. Stove top with blower on medium is 485F. If this was hardwood the stove temp would be around 550F at this stage. This is verified with an IR thermometer. I suspect the insert face temps you are reading are on the low side which is ok, just relative to the thermometer location. The stove tends to burn front to back so this may just be a verification that the stove is hotter in the back at the later stage of the burn. I'll take some IR readings at multiple locations to check.



Face readings on the top of the door are in the 320-330F range.

 

[Squisher]

I read face temps with a magnetic thermometer as pictured on my super insert and 200-250 would be low. 375 not bad, but I regularly see 450-500+.

It seems when I have decent secondary combustion the face temps jump right up.

 

[Squisher]

Here's my summit nearing the end of my morning load about seven/eight hours ago. Pipe temp 214. Stovetop around 300 still. This load hit 600 plus stove top and then over the course of the burn drifted down to the 300. I also hit single wall exterior flue pipe temps of 500+ while off gassin the load and getting the stove temp up. I had lots of coals overnight for a hot morning reload burning some birch.

 

[Log Splitter]

Burns are starting to get a little better. I think I'm getting what's expected. I think my expectations were possibly off.

I can have my temperature range between the mid 300s and the low 700s over a 10 hour period.

The two main factors effecting my stove temperature are the air I give it, and the air being blown out by the blower. If I open up the airflow, early in the burn I can easily eclipse 700 with a fully loaded stove. I make sure that air is choked at no later than 500 degrees. If the stove temp keeps increasing, I continue to amp up the blower. This undoubtedly stabilize and then begins to lower the stove temp.

When I do a load tonight, I'll keep track of times/temps/stove settings just to see if you guys thing my stove is behaving properly.