Lopi 1750i Insert Rising temps on secondary burn

[Tbork497]

Hey guys! Brand new here (to the forum and to wood stoves).
I have a brand new 1750i (going on about 2-3 months with at least 1.5 months of consistent use/fire) that I am trying to learn.
Here's a basic scenario that I have concerns on, that I wanted some experienced users advise on:

I get a good fire going throughout the day (450ish on temp) and have a great bed of coals. When getting ready for an overnight burn, I spread the coals around evenly throughout the box, and load it down with wood (seasoned, dry, approx 9-14% moisture). Let it burn with the air inlet anywhere from 1/2 ways to fully open for about 3-5 min, and then shut it down to 1/8" to 1/4" open on the air inlet. Temp may be around 500ish at this point, and then after a few min, it starts to drop.
Here's where I'm not sure if I have a problem or not: After about 1-1.5 hrs, the temp rises quickly to 700ish+ and I get a mean secondary burn. Both times that I caught it, I shut the air inlet to closed and then opened the bypass to help cool things off. Then after shutting the bypass back to closed, it will settle down to 400-450ish, and the start to climb again.

I guess my question is, seeing as I'm brand new to this:
Do I even have a problem, or is this something for concern?

I'm happy to provide any other details you may need. Just hit me up.

Thanks guys!

 

[Woody Stover]

What kind of wood are you burning, and how big are the splits? Do you load E-W (splits across) or N-S (front to back?) Instead of spreading the coals out evenly under all the wood, try pulling them forward, or in a N-S line down the center of the box, or even shove some of them to the back. The aim is to get the load to gas in a more controlled manner. If all of the load is on coals, you get a lot of wood gassing at once and the secondary blazes. Shutting the air down earlier also controls gassing, but it sounds like you are already doing that.

 

[Tbork497]

What kind of wood are you burning, and how big are the splits? Do you load E-W (splits across) or N-S (front to back?) Instead of spreading the coals out evenly under all the wood, try pulling them forward, or in a N-S line down the center of the box, or even shove some of them to the back. The aim is to get the load to gas in a more controlled manner. If all of the load is on coals, you get a lot of wood gassing at once and the secondary blazes. Shutting the air down earlier also controls gassing, but it sounds like you are already doing that.

Thanks! using mainly Oak that is anywhere from 3"x3" to 5"x5" (some few pieces larger) from 8"-15" long.
Loading N-S.
I will try the front coals method to see if that helps. My main concern is making sure I'm not doing something unsafe. The temp rise usually takes 45-90min after I shut it down, so I'm long in bed by that point, and my not even know it when it happens. But I wasn't sure if this wasn't just completely normal, or that the 700 temp was normal...
Again, thanks for the help with the newbie!

 

[begreen]

What you are seeing is the peak bloom of gases being burned off the wood. A 650-700F stove top can happen then. For a bit lower temp and a little longer burntime try loading your largest splits overnight, with little air space between them and also shutting down the air sooner.

 

[Tbork497]

Thanks! I will give that a shot


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[lopiliberty]

My liberty does the same thing. You think it's all settled in and ok come back an hour later and you have insane secondaries going on with quickly rising temps and I even uses fairly large wood. Almost 8 years with this stove and it still "SURPRISES" me on a regular basis

 

[begreen]

A few years back I stopped paying attention to stove top temp and run the stove by flue temps. It's made a nice improvement in predictability.

 

[Tbork497]

The 1750i is an insert. How would I monitor flue temp when the pipe is not exposed? (Again, sorry for the basic questions, just new at this)


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[begreen]

Inserts are more challenging. Visual clues are good. If you want to monitor flue temps the best solution will be a digital monitor with a remote sensor on the liner.

 

[redktmrider]

Inserts are more challenging. Visual clues are good. If you want to monitor flue temps the best solution will be a digital monitor with a remote sensor on the liner.

I have the Auber thermometer on my Alderlea insert, it has helped tremendously!
https://www.auberins.com/index.php?main_page=product_info&cPath=17&products_id=292

 

[Tbork497]

Thanks I’ll look into that


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[lp9900]

Since I’m about to have this unit installed I’m watching this thread. What stove top temp is too high? Also let us know if you’ve managed the secondary burn better and how you did it.

 

[Tbork497]

Still trying to find a happy medium on the secondary burns. When I get a good one going, it dies out within mins. I have tried using less wood/larger pieces at night for the long burn, but it just makes the fire not last as long (which is to be expected I guess). Still riding this learning curve...


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[DBoon]

I have a Loop 1750 (not an insert) in a house I am renovating. It is connected to a double-wall insulated liner running 25' straight up. It is impossible to keep this stove from running at 700-750 degree stovetop no matter how soon I shut it down. Having said that, it is a well-built stove that can take these temps during the peak of the burn with no problems.

The rise you are seeing overnight is what I get with hickory on my Lopi 1250 (different house). The hickory takes about 90 minutes to really off-gas, and then the stove will go into overdrive for 45 minutes while it burns the gases off. One of my favorite mixes of wood in this stove is 50/50 cherry and hickory - the cherry lights off quick and gets the hickory going, and the hickory goes nuclear when the cherry is winding down.

 

[Woody Stover]

I have a Loop 1750 (not an insert) in a house I am renovating. It is connected to a double-wall insulated liner running 25' straight up. It is impossible to keep this stove from running at 700-750 degree stovetop no matter how soon I shut it down.

I bet a pipe damper (or two) would give you more control..

 

[DBoon]

I bet a pipe damper (or two) would give you more control..

Yes, I have one installed. I've used it a couple of times when it's been really cold (below 0 degrees) outside and I need to slow down the draft. I'm glad I put it in.

But the reality is that this stove seems to like to run hot, and a 700-750 degree stovetop for an hour doesn't seem to bother it. Having said that, I would recommend that this stove be outfitted with a blower for when this happens. In the temporary install I have I simply blow a fan across the top of the stove to move the heat away.