New Lopi Flush Large Next Gen

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Silversniper

New Member
Jul 11, 2021
32
Australia
I just have the Lopi Flush Wood large installed. I think its the new Next-Gen model. It’s my first ever stove and although I am slowly inproving with it, I am a little disappointed with the results I am getting.

I don’t seem to achieve much, if any, secondary burn unless the fire box is fully stoked with lots of flame. I expected I would still get visible secondary burn on a moderate burn.

As noted above, the fire seems to want to revert to smoldering quite readily, even with the lower air intake all the way in. I expected that having the lower rod pushed all the way in
would give me a result similar to having the door open a crack.

Overall, the heat output is lower than expected. Even with the fan in operation. I can stand right in front the fire without discomfort or feeling like my pants are getting dangerously hot. Is this normal?

Is it possible that these issues are caused by the flue not being properly sealed by the installer?
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
If the flue is too short, that could affect performance or if it is vented into a large chimney flue instead of a 6" liner, that too could affect performance. Is the insert connected to a 6"/150mm stainless liner all the way to the chimney top? How tall is the chimney?

Normally this inert is a strong heater. Has the bypass been closed after the fire is burning strongly? What temperature is the catalyst reading? Has the wood been checked for moisture content in its core?
 

Silversniper

New Member
Jul 11, 2021
32
Australia
Thanks. It’s the new, non-cat version of the Flush Wood large. So, I don’t have an inbuilt temperature reading to use. I have ordered a magnetic thermometer but don’t know where to place it on an inbuilt (as the metal fascia temperature varies considerably depending on location)

The chimney is one storey of 6” pipe and the installer decided to put an extension on it so it is well above the roof ridge line. I doubt chimney length is the issue.

The wood is Australian hardwood at about 15% MC.

The main issue I am having is the heat output. The previous open fire would get our small lounge room really hot. I expected this unit would perform that function even better. This unit does get the masonary chimney very hot (after being on a few hours) but that heat barely radiates into the room- it seems to all go upward alongside the chimney and then cools up in the ceiling area. The far side of the small lounge is only barely warm. The internal air blower is loud and I don’t like to set it at more than 40%.

The second issue is the lack of secondary burn. I expected secondary burn to take place easily and often - but it seems the unit needs to be extremely hot and full with flaming wood before any secondary gas is burned.

The installer did commment that the unit almost filled the entire fireplace- how do I know if the flue is properly sealed to the top of the unit? The Lopi manual indicates this is an inportant step.

Not having been a member of these forums - I don’t know if the installer put in an insulated liner or block off plate, as I didn’t know what these were.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
One story flue systems often come up short. From the stovetop to the liner cap should be at least 4.5-5 meters tall. If the outdoor temps are mild then a shorter chimney may underperform with weak draft. Leakage at the flue connection would affect draft. In order to see the flue connection, the front shroud (surround) would need to be removed.

How was the wood moisture checked? Was the wood moisture checked on a log that was resplit in half, then tested on the freshly exposed face of the wood?
 
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Silversniper

New Member
Jul 11, 2021
32
Australia
Thanks for all rhe help - I will recheck wood MC using the freshly split method.

The flue connection to the unit is barely visible if I remove the fascia, but I can try this.

Should the masonary chimney have an insulating cap around the metal flue at the top, as well as the block-off plate at the bottom? I am starting to think that may be where the heat is being lost. Shown is a test fire during install. The masonary above the mantle gets hot to touch - is that an indication that heat is being lost?

53961441-E2A5-4034-B386-B711FD654870.jpeg
 
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begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
Yes, the wood must be tested at the inside grain. The outside dries much quicker than the interior of the wood. That is a nice looking set up. The test fire doesn't look too bad.

Was the liner insulated? That will help if the draft is marginal. If not, that would explain why the masonry is warming up. Can you hold your hand on the hottest area for a bit?

Another thing to try is to open a nearby window a couple of centimeters and see if that perks up the fire.
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
My friend has this stove fireplace X next gen. His stove heats his entire house its a 2 story and the stove room gets to warm sometimes. He purchased his wood from me so I know his wood was completely dry. You might want to check you wood moisture. Lopi makes a good stove, so it may be one of 2 things draft or wood or a combination of both
 

Silversniper

New Member
Jul 11, 2021
32
Australia
(Thanks, I will respond once I have done those checks. I am also concerned I have hijacked this thread -mods would you mind opening this as a new thread maybe titled ‘Lopi Flushwood Next Gen’?)

I have located a better photo during install -noting the limited clearance at the top of the unit, do you forsee any issues with securing the flue to the top of the unit? My inability to check this is one reason I am identifying it as a possible cause of low performance.

99E0BC71-A71F-433C-B0B5-5926E8366DD4.jpeg
 
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clancey

Minister of Fire
Feb 26, 2021
1,421
Colorado
Your fireplace is going to be just beautiful when its finished--lots of work you did...Yea that Begreen as much as he moved my threads around and closed some as well he will fix you up with a nice thread..lol lol I just bought and put my stove in and have not lit it yet and just got my wood in as well...First time wood stove owner and do not know much about them but yours is going to look really nice..old mrs clancey
 

Silversniper

New Member
Jul 11, 2021
32
Australia
Ok I lit the flushwood tonight with more success - thanks to all the good advice on these forums.

Basically, I ignored the manual and tried to get the thing as hot as reasonably possible from the get go. So, I used a big pile of assorted starter fuel, (kindling, paper and firestarters), a load of small splits after that, only medium size splits after that.

Then, I cranked up the fan to around 70% (to about the sound of a loud hairdryer).

This got lots of good secondary combustion and also got the room to around 78*.

But, to achieve this outcome I had to leave the door ajar about 4 inches for most of the first hour, until the fascia was warm to the touch. Closing it simply caused smoke inside the firebox, even with a big raging flamey fire going inside.

This is not what the Lopi manual suggests.

I was also a lot more cautious about closing the damper - I didn’t touch it until about 1.5 hours of seriously hot burn and then I closed it only about an inch every 15 mins. I only started slowing primary airflow at about the 3 hour mark, when the unit was pumping out heat and everything was fully ablaze.

So, a good result and my gratitude to all those who posted tips here, but I don’t think my starting issues are typical - suggests to me that there is a draft or leakage issue in the flue.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
What is described could also be a result of cooler outside temp helping draft, or not fully seasoned wood, or a fire that is a bit starved for air, or a combination of these.

Did you try opening a nearby window a little bit to see if that helps the fire?
 

woodgeek

Minister of Fire
Jan 27, 2008
4,392
SE PA
Huh. I got the same stove installed in late spring, and got to burn it for one day (to cure the paint) before summer arrived here, so I'm hardly a veteran. I've got a 24 ft long chimney with a 6" liner BTW.

I burned an old (1980s) stove for many years, and I found the air control on the new quite touchy. I actually put out the fire by accident by pulling the air out before the wood was fully engulfed (I was curious what would happen).

I concluded that air even all in 'all in' was still quite low air supply (even with my tall chimney) versus my old stove expectations...and I think this is how they get the high efficiency and EPA rating. This means that the fire has to be well caught (with dry wood) before you close the door. With a big load I think this is easy enough, but a smaller load it is hard to get it hot enough to 'power the system'.

I think if you want less heat, you still load it full, get it roaring, close the door, and then (gradually) pull out the air in steps. This air reduction reduces the combustion rate despite the large load, and the secondaries prevent it from smoking too much (if its hot enough to light them).

Basically a large load and high heat is easier...FILL IT UP, and keep the air pushed in.

So yeah, that's what I concluded from doing successively larger break-in fires...not very clean burning (smoky) on the smaller loads and not a lot of secondaries, for the above reasons. When I finally got to the last (full load) burn it was throwing crazy heat and secondary fireworks.

Bottom line: even with my tall stack and dry wood (sawdust bricks) I couldn't get a proper hot fire from a cold start with a small (less than half full) load. I suspect that once it had an ember bed, I could toss in a half load and it might be fine. Ofc, with more practice I might figure that out.
 
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Silversniper

New Member
Jul 11, 2021
32
Australia
Thanks woodgeek, that is a super useful post and I am relieved that someone with your experience has encountered the same issues with this unit.

It may also explain why the instructions in the manual are misleading - they may not have updated the user instructions from the hybrid fire version of this unit.

Although I think more practice and experimentation is in order, it seems the door open/low air/too easy to go out situation isn’t related to the chimney and draft and may be related to the unit’s air supply. Can I alter the main air supply to allow more air to get in, or is that too drastic a step at this stage?
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,967
Woolwich nj
Thanks woodgeek, that is a super useful post and I am relieved that someone with your experience has encountered the same issues with this unit.

It may also explain why the instructions in the manual are misleading - they may not have updated the user instructions from the hybrid fire version of this unit.

Although I think more practice and experimentation is in order, it seems the door open/low air/too easy to go out situation isn’t related to the chimney and draft and may be related to the unit’s air supply. Can I alter the main air supply to allow more air to get in, or is that too drastic a step at this stage?
It is illegal to alter the stove, it states it in the manual. altering will also void any warranty. I strongly suggest not doing that. I posted a question earlier. What is the moisture content of your wood. some of your issue sounds like sub parts wood, bgreen also suggested it. One of the ways in which we help you out it to rule out any or all of the potential issues someone like yourself are having. so do you have a moisture meter, and if so what is the moisture content of the wood your burning.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
Can I alter the main air supply to allow more air to get in, or is that too drastic a step at this stage?
If the house is well sealed and tight, you can alter the combustion air by cracking open a nearby window a little. If that improves the fire then the stove needs outside air. If no change, then move on to resplitting some logs and testing for moisture on the freshly exposed, core face of wood.
 

woodgeek

Minister of Fire
Jan 27, 2008
4,392
SE PA
I agree the manual is unclear, and the hybrid manual is different from the non hybrid.

For the record, I don't think there is anything wrong with the stove, and the 'stingy' maximum primary air is key aspect of the design that allows it to achieve the efficient clean burns I want. Maybe someone coming from a different modern stove would've adapted to it naturally, but for me coming from a 40 year old stove, it took a little experimenting to get the hang of it.

I would often light a small load in my old stove, and I would give it as much air as needed to not smolder/smoke. For large loads, this was ok, but for small loads, the firebox didn't heat up much and much of the heat went up the flue. A modern stove doesn't allow me to do this.

I also agree that you should verify that your wood is dry by splitting and remeasuring. But as a new user of a 2020 stove, I was surprised how it burned with (completely dry) wood bricks.

I can't wait for cool weather to fire it up again.

One last thing: something true of all stoves is that you can't adjust them too fast IMO. The manual mention this. When you close the door, you immediately reduce the air flow alot, and the fire dies down. But then because there is less fresh cooling air coming in, the fire gradually starts to heat up again, and the draft increases and you are back in business. It takes a few minutes for this rebound to occur.

Similarly, when adjusting the air, you have to go in steps, waiting a few minutes in between.
 

Silversniper

New Member
Jul 11, 2021
32
Australia
Thanks Woodgeek and others - lots of useful tips. Further experimentation is definitely required - if it turns out this is all down to how I am using the stove, I will be happy. I would feel a lot more comfortable if this wasn’t a new model that was only recently brought out, but I am going to hold off on drawing conclusions until I have tried some of the suggestions.
 
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clancey

Minister of Fire
Feb 26, 2021
1,421
Colorado
At least you all are experienced and I still have to light mine for the first time and my dealer is going to light it for me so you know the trepidation that I will go through --lol We will figure out our stoves in the very same year...clancey
 

Shrewboy

New Member
Oct 15, 2020
71
Eastern Pennsylvania
(Thanks, I will respond once I have done those checks. I am also concerned I have hijacked this thread -mods would you mind opening this as a new thread maybe titled ‘Lopi Flushwood Next Gen’?)

I have located a better photo during install -noting the limited clearance at the top of the unit, do you forsee any issues with securing the flue to the top of the unit? My inability to check this is one reason I am identifying it as a possible cause of low performance.

View attachment 280200

Install looks great! hope you can figure out the issues asap and enjoy it :D
 

Hoytman

Feeling the Heat
Jan 6, 2020
356
Ohio
Man...I am seeing red flags all over the description of the burn by the user. If you can get a raging fire like that with wet wood, there should be plenty of air and heat to ignite the secondary without waiting three hours to turn it down. If the wood is dry, still no reason to wait that long to start turning things down and no reason to leave the door open that long either...wet or dry.

Just make sure the wood is dry.

No reason for the masonry above the mantle to get so hot you can barely touch it unless something is wrong. So, first...there’s your sign. I would stop but burning the stove and check the connection to the stove and make sure it is connected. Should be an insulated liner as well.

I always hate to see posts where people are pushing their stove to maximum all the time. If you have to burn a stove like that either something is wrong it is is really undersized for the job. A correctly sized stove or insert should only have to be pushed to the limit only on the coldest of days. Why wear out a stove before it’s time? My opinions...and I’m sticking to them. Others mileage may very and that is fine.
 
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Silversniper

New Member
Jul 11, 2021
32
Australia
Ok had the installer over today and he was really helpful. He thinks that because the stove is sitting so high in the opening, and because the masonry directly above it as 8” thick ( with a metal lintel), the lintel is operating as a big heat sinking directly over the stove and preventing the top of it from properly heating up. This explains why the area of masonry around the mantle is so hot.

He suggested some hebel blocks on top of the stove but couldn’t fit them as it was too tight a space. So he now he thinks a thin layer of rockwool with foil on one side may work. But, I think it needs to be taken out and a row of bricks removed from underneath, lowering it away from the lintel.
Any thoughts?
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,761
South Puget Sound, WA
Looking at the picture of the insert without surround, it looks like there is about a 1" gap between the insert top and the lintel. Is this correct? If so, that should be adequate. A more likely cause for heating up the masonry above is a lack of an insulated block-off plate sealing off the damper area.

Has a proper testing of the wood moisture been done yet? Was a fire tried with a nearby window or door open a crack?
 

Hoytman

Feeling the Heat
Jan 6, 2020
356
Ohio
After all other sources of heat mentioned above are tended to, and you have a gap where insulation is recommended to be installed, then rock wool combined with the same refractive insulation material used above the fire boxes of some stoves could be combined to further help resolve the issue.