Scratching my head raw about my short burn times

[Downtown Bruno]

I'm only getting about 2.5 hours of burn on my VC Encore 2040 CatC. I'm getting tired (literally) of setting my alarm 3x every night just so I don't wake up to a cold house. I'm hoping the oracles here can tell me what's going on with my stove. Someday, I'd like a good night's sleep. Here's the bullet:

Before bed, I make sure I have a stable stovetop temp between 450 and 600. That requires the bypass handle forward (Cat activated) and the damper set at about 3/4 closed. I top off the box to full with another log or two of seasoned hardwood and traipse off to la-la land. By the time my alarm goes off 2.5 hours later, the wood is already reduced to embers and the stovetop temp is down to 300. I add more wood and go back to bed. Second verse, same as the first until morning.

I replaced the combustor this week, and am now getting 4 hours on a full load, but I'm hearing all these claims that I should be getting 8-12 hours. What gives?

By the way, the cat thermometer behind the stove above the fan that has a range reading "Activate Catalyst" never budges even when the stovetop temp is at 700. The probe inside below the combustor looks okay. I just activate the combustor whenever the stovetop hits 400 or so.

 

[EatenByLimestone]

How tall is your chimney?

 

[stoveliker]

Are the ashpan and main and top doors properly sealing?

 

[Ctwoodtick]

We here on Hearth.com always ask about wood dryness when fielding questions like yours. The following is the best way to know you have good dry wood.:
Use moisture meter (inexpensive is fine)- c make sure wood has been at room temperature for a day or so and split a piece of your wood. On that fresh face of split wood, use moisture meter. Dry enough is considered 20 % moisture content or less and you can rule out wood dryness as the issue.
I ask because subpar wood is often the culprit to burn time issues.

 

[Ryan_C]

8-12 hour burns on that stove are usually low, extended burns, not a hot 500-600 stovetop overnight. At those temps, you’re going to go through fuel faster. Check your air control and gasket, seal condition even slightly too open or minor air leaks will shorten burn time a lot. Use larger splits that are not too dry (however, mind that too wet kills efficiency).

The cat thermometer not moving is a bit odd - that could be part of it if the cat isn’t actually staying active.

You’re probably not far off, but getting into those longer burns usually means running the stove a bit lower and tighter, not hotter.

 

[Downtown Bruno]

Great questions and advice. I'll check the gaskets. The stove is six years old with the original gaskets.
I have a moisture meter and check my wood on the outside of a split, but not the inside. My outside readings are around 15%.
The chimney is about 20 feet tall.

How do I tell if the ash pan is sealing properly? Can I assume so if the gaskets are fine?
Thanks, everyone.

 

[Downtown Bruno]

FYI, all my gaskets look good.

 

[Eman85]

My stove is the original version of the Encore so it's different than yours. My lever on the L side of the stove is forward to open the bypass damper and move to the rear to close the damper and send the flue gas to the cat.
I never had a factory cat thermometer, I installed a probe for the digital Auber meter to monitor cat temps. With the cat engaged and up to temp and the air intake cut back more then 3/4 to control the cat my stove top will drop. Set like that I can burn overnight with a full firebox, wake in the morning and open the air and can burn another couple of hours before reloading. It's easily a 12 hr. burn as I reload at 10PM so I have time to get the cat where I want it before going to bed.

 

[dmccoole]

What type of hardwood? Maple can burn a lot quicker than red oak.

What size splits? A bunch of smalls burn quicker than a few large splits

Even though the gaskets look ok, they do compress over time. Do the dollar bill test. Ensure the front doors and ash pan door are locked tight

Verify the primary intake flapper on the back of the stove is closing with the primary handle.

What does the fire box look like when you have the stove all set for a long burn after an hour or so? I'm imagining the box is full of flames causing the wood to burn quickly indicating an air leak.

 

[Downtown Bruno]

What type of hardwood? Maple can burn a lot quicker than red oak.

What size splits? A bunch of smalls burn quicker than a few large splits

Even though the gaskets look ok, they do compress over time. Do the dollar bill test. Ensure the front doors and ash pan door are locked tight

Verify the primary intake flapper on the back of the stove is closing with the primary handle.

What does the fire box look like when you have the stove all set for a long burn after an hour or so? I'm imagining the box is full of flames causing the wood to burn quickly indicating an air leak.

"Verify the primary intake flapper on the back of the stove is closing with the primary handle."
Do you mean the flap inside the stove that diverts the air flow so that it goes through the combustor?

 

[Downtown Bruno]

I use mixed hardwoods. Never paid much attention to the species as long as they were hardwoods. I guess I could bone up on that.
Dollar bill test: most places show good resistance. One window on the front, though, has some rattle to it.
Split size: four splits usually fill the box.

 

[dmccoole]

"Verify the primary intake flapper on the back of the stove is closing with the primary handle."
Do you mean the flap inside the stove that diverts the air flow so that it goes through the combustor?

It's more of a metal plate that slides up and down. It's on the outside in the back near the bottom of the stove. You should be able to see it open and close when the primary air lever is operated.

 

[Eman85]

If you light a fire and let it burn with the air intake open all of the way to get the stove top over 500 what happens if you close the air down? Don't touch the bypass damper, just close the air down and observe the flame in the box. You should be able to close the air down to where it just smolders and then open it and the fire should roar back. If you can't shut it down like that and your air control flap is closing you have an air leak past a gasket somewhere.

 

[stoveliker]

^^this.
And do the dollar bill test.

 

[Downtown Bruno]

It's more of a metal plate that slides up and down. It's on the outside in the back near the bottom of the stove. You should be able to see it open and close when the primary air lever is operated.

^^this.
And do the dollar bill test.

Thanks. I'll do that test tonight.
I found the primary air intake in the back under the fan. On mine, though, it's not so much a plate that slides up and down, though, but a door flap hinged on the top that opens and closes when I move the damper/primary intake lever. Am I on the same page?

The dollar bill test was successful. I had good resistance all around, but could still pull it out. I assume "good resistance" is good enough? I do have a loose window, though. So I need to replace the gasket there.

 

[stoveliker]

Good resistance is good.

 

[moresnow]

I do have a loose window, though. So I need to replace the gasket there.

Might as well fix this issue and eliminate it from the mix.

What happens if you close down the primary air further?
Can you reduce primary air until the stove is running/maintaining acceptable stove top temps without active flame? Relatively common routine on some makes of Cat equipped stoves.

 

[Eman85]

Do the burn test, don't worry about the cat just burn it. Have you cleaned and or inspected your chimney? The reason I ask is if you burn it wide open with no cat it gets flue temps up high if not cut back by closing the air. It is a good way to start a chimney fire if you have any buildup. Do you have a flue temp. thermometer? A good investment is a digital thermometer for the cat and a flue temp thermometer. If you have double wall flue it's best to drill and put a probe in.

 

[Downtown Bruno]

The burn test last night showed a significant reduction in flame after the primary intake was fully closed. See before and after image attached.

After loading up the box and achieving a glow with only a minor flame on one side, and the stovetop temp at 450, I went to bed. The bypass was activated and the primary was at about 50%. (I don't yet have a cat thermometer.) I got up 5 hours later to find only embers; not enough to mess with to reignite a new load.

The chimney was cleaned in October with all the stovepipe replaced. (Due to a chimney fire last winter, but that's another story. This time, the stovepipes were installed by a much more reputable installer and the stove has worked much better than before. But the short burn time remains a conundrum.)

Question: if I go to bed with a full load and very little flame, 450 stovetop temp, a nice glow, shouldn't I still be getting more burn time than that? Could the loose glass in the front door cut the burn time in half? (With very little flame, it can't be leaking that much, can it?

I will consider a flue temp thermometer.
Thanks in advance.

 

[Eman85]

I hot reloaded at 11PM last night and it's noon here now and my STT is 400 and I have enough embers that I could reload and get a hot fire going. Only thing I did was open the air a little about 9AM for a little more heat. The load was all oak branch rounds, not split, anywhere from 2" to maybe 5" and 3 or 4 years old.

 

[dmccoole]

It sounds like the stove is getting too much air. That air usually comes from the gaskets in the front doors, ashpan door, or griddle or the glass in the front doors. You could try putting in a damper in the stove pipe to reduce the air outflow.

 

[Downtown Bruno]

Okay. I think I'll:
Get the digital cat thermometer
replace all gaskets, including windows
test again in the fall.
Thanks, everyone, for your excellent advice.