Noob Q on a Lopi 1750 insert

[Will_f]

So I just put a Lopi 1750i in my house and I’m thoroughly enjoying it. However, I have a question that hopefully some folks can help with. The particulars are:

The house is 2000-2300 SF (haven’t actually measured). It’s well insulated (R25 walls, triple pane windows, etc).

The insert sits downstairs and heat is able to move easily upstairs. The vent on the stove is connected to 8’ of flexible liner, which is connected to another 16 feet of single wall liner. The chimney itself is inside the thermal envelope of the house and drafts even when the stove is cold.

At 30 degrees outside the Lopi will heat the entire house burning 1 or two splits an hour on a bed of coals. I’m burning splits of spruce which are fairly dry (1 season).

I’m only really running the stove hard on light off with no coals. Once it’s drafting well, I leave the air wide open to 3/4 open and just add a split or two per hour placed along with the coals towards the back of the firebox. I haven’t measured the surface temperatures on the stove, but they’re probably around 250-300.

I realize this is probably the most common problem on the forum, so I recognize I may not be successful, but here it is: The glass will soot up in a day when I run it as described above. Is there a better way to run the stove where I can keep temperatures in the house reasonable, not have lite a cold stove 2-4 times a day and still be able to enjoy the fire without cleaning the glass daily?

I have tried running the stove fully loaded and dampered down but that really soots the glass fast.

Thanks,

Will

 

[webby3650]

Hmm...
Typically you fill the stove each time you load it. Burning in cycles is more efficient.

250-300 is a very low stove top temp. If the wood was dry, and the stove was 3/4 throttle you should be seeing 5-700 degree temps. The glass doesn’t typically get dirty on these stoves unless the primary air is turned off way too soon. Or If the wood is under seasoned.

It’s also designed to run on a 6” flue, did you already have an 8” liner in the chimney?

 

[Locust99]

When you say your glass is sooted up do you mean it has like light colored ash on it, or is it black? Like webby said, after establishing coals and the stove is warm I would load it up. Then slowly adjust the air control after the fire is established.

I would get yourself a moisture meter and check the moisture content of your wood, and also either get a IR thermometer or stove top thermometer to measure the temps.

I have a lopi answer which is smaller than your stove, and my glass will get like ash on it that’s light gray and easily comes off with windex. Also I start with a small hot fire and build it up till I can load it full then go from there.

My stove tops run typically from 500 to 700 with the blower on about half power, as it’s an insert.

 

[Will_f]

Hmm...
Typically you fill the stove each time you load it. Burning in cycles is more efficient.

250-300 is a very low stove top temp. If the wood was dry, and the stove was 3/4 throttle you should be seeing 5-700 degree temps. The glass doesn’t typically get dirty on these stoves unless the primary air is turned off way too soon. Or If the wood is under seasoned.

It’s also designed to run on a 6” flue, did you already have an 8” liner in the chimney?

I must not have been as clear as I thought. The liner is 6 inches. Eight feet of the liner is flexible, sixteen feet of the liner is smooth wall straight. Total length is 24 feet.

The low surface temps are because I am running excess air (a lot of excess air) and you’re right- it is inefficient. It just soots up slower than if I load it full and damper down to low airflow. Essentially The Fire is limited by fuel rather than air.

I’ll take a picture tonight and add it so you can see

 

[webby3650]

I must not have been as clear as I thought. The liner is 6 inches. Eight feet of the liner is flexible, sixteen feet of the liner is smooth wall straight. Total length is 24 feet.

The low surface temps are because I am running excess air (a lot of excess air) and you’re right- it is inefficient. It just soots up slower than if I load it full and damper down to low airflow. Essentially The Fire is limited by fuel rather than air.

I’ll take a picture tonight and add it so you can see

Ahh, I see that now. My confusion.
After a full load, do you slowly reduce the air over a period of time?

 

[Will_f]

When you say your glass is sooted up do you mean it has like light colored ash on it, or is it black? Like webby said, after establishing coals and the stove is warm I would load it up. Then slowly adjust the air control after the fire is established.

I would get yourself a moisture meter and check the moisture content of your wood, and also either get a IR thermometer or stove top thermometer to measure the temps.

I have a lopi answer which is smaller than your stove, and my glass will get like ash on it that’s light gray and easily comes off with windex. Also I start with a small hot fire and build it up till I can load it full then go from there.

My stove tops run typically from 500 to 700 with the blower on about half power, as it’s an insert.

Yup, I need accurate temp measurements. I’ll borrow an IR camera and see what I’m really getting.

The moisture meter will take a few days I think.

 

[Will_f]

Ahh, I see that now. My confusion.
After a full load, do you slowly reduce the air over a period of time?

Actually no. I pretty much leave the air wide open. I load up the box about 1/2 to 3/4 full (7 or so splits) , get a really ripping fire going which runs an hour or two and when it’s down to coals throw a split or two on per hour. If the stove starts getting really hot I’ll damper it down to maybe 1/3 open, but mostly I let it burn down to a pile of bright red orange coals.

 

[webby3650]

I don’t know then. These stoves usually have very clean glass, but would run a much hotter stovetop. A full load left on high burn would run up to 900 degrees even, pretty easily.

 

[begreen]

If the glass is sooting up with the air 3/4 to wide open then it sounds like the wood is not fully seasoned. With good dry wood you should be able to close down the air almost if not all the way and have robust secondary combustion with a clean glass on just a few splits of wood.

 

[Will_f]

If the glass is sooting up with the air 3/4 to wide open then it sounds like the wood is not fully seasoned. With good dry wood you should be able to close down the air almost if not all the way and have robust secondary combustion with a clean glass on just a few splits of wood.

Could be. I’ll get a moisture meter and find out for sure.

 

[begreen]

To test, let the split come up to room temp. Then take it outside and resplit it. Put it up to your cheek. Does it feel cool and damp. If yes, then it is not dry inside. If you have a meter then test at this point on the freshly exposed face of the wood. Press the probe points firmly into the wood.

 

[Will_f]

Update:

Fired it up from cold. Wood came from outside (19 F). Stuffed the box full and lit it off with kindling and cardboard. Was at 400 or so within 15 minutes and at 600 within 25 mins. Started throttling the air at 600, and it rose up to about 650 before cooling down a little (air maybe 1/2 closed?) at 35 minutes. No soot on glass. A little haze showed up early on but burned off. At 40 mins it’s about 610 at 1/2 air. Based on what I’ve read I’d say the wood is dry enough.

So, it looks like if I don’t want soot on the glass I can get there by running at 600. I just have a very warm house.

 

[begreen]

Try turning down the air some more. To 25 or even 12 %.

 

[Will_f]

Try turning down the air some more. To 25 or even 12 %.

Ok. I’ll try that tomorrow. I’m guessing that should drop the temp a good bit. Stop at 500 or keep heading down?

 

[Will_f]

When you say your glass is sooted up do you mean it has like light colored ash on it, or is it black? Like webby said, after establishing coals and the stove is warm I would load it up. Then slowly adjust the air control after the fire is established.

I would get yourself a moisture meter and check the moisture content of your wood, and also either get a IR thermometer or stove top thermometer to measure the temps.

I have a lopi answer which is smaller than your stove, and my glass will get like ash on it that’s light gray and easily comes off with windex. Also I start with a small hot fire and build it up till I can load it full then go from there.

My stove tops run typically from 500 to 700 with the blower on about half power, as it’s an insert.

Brownish grey (light colored). I can get mine up that hot, it’s just if I do, the House gets quite warm. I was hoping for advice on how to minimize sooting while running the stove backed way down, or if that’s not practical, advice for pumping a bunch of heat out, then backing it off so that it’s easy to get going again when the house starts to cool off.

 

[dafattkidd]

You’ll get better at this. Keep playing with it. Generally it’s best to load three splits at a time minimally. These units need to burn hot to burn cleanly and efficiently. If it’s getting too hot, turn the fan off and wait a little longer between reloads.

 

[begreen]

Ok. I’ll try that tomorrow. I’m guessing that should drop the temp a good bit. Stop at 500 or keep heading down?

Quite the opposite. If the wood is dry the temp is likely to rise as more robust secondary combustion kicks in.

 

[blacktail]

You want to turn the air down as much as you can while still maintaining secondary combustion.
I occasionally load 1-2 splits at a time, as you've described, when the house is warm. Usually at about half throttle. But my glass always stays clean.

 

[Will_f]

Thanks guys.

It appears the correct strategy is to keep the stove hot enough to maintain secondary combustion. If I do that, the glass stays clean.

So if I run it to stay warm all night long, I’ll have to burn the soot off the glass with a hot run in the morning, correct?

 

[Will_f]

Picture of the glass this morning- let the stove burn out last night at about 1/2 air.

 

[bholler]

Thanks guys.

It appears the correct strategy is to keep the stove hot enough to maintain secondary combustion. If I do that, the glass stays clean.

So if I run it to stay warm all night long, I’ll have to burn the soot off the glass with a hot run in the morning, correct?

No you shouldnt. If you have good fuel you should be able to shut down most of the way if not all the way and have pretty clean glass

 

[begreen]

View attachment 218202
Picture of the glass this morning- let the stove burn out last night at about 1/2 air.

There are a couple things that could be happening here. A split could have been too close to the glass on the left side.The left side split could have been poorly seasoned.

If the stove glass is clear all the time except for this area then check the gasket in that location for leakage. This could be due to poor seating or poor gluing in that area. Do a dollar bill test to see how good the seal is there.

Today, close down the air even more, to at most 1/4 open.

 

[webby3650]

I really don’t think you are doing anything wrong. I would load mine up at bedtime and shut the air almost off. In the morning there was still coals, brown glass that burned right back off easily. I was loading an already hot stove with coals just to clarify.

 

[Chimney Smoke]

I have a Lopi 1750 free standing stove. I close my air 3/4 to 7/8 on every reload and never have brown soot on my glass. I think you will find that your wood is a bit high in moisture. If i ran my air half open on 3 or 4 hardwood splits I think I'd be worried about my stove melting. I regularly let the stove burn out overnight and go to bed with the air almost all the way closed with no soot on the glass. The airwash on these stoves is pretty good.

 

[webby3650]

Keep in mind that everyone’s experience is going to be different. No one can say it’s normal or not normal, all they can do is give suggestions. Stoves are driven by draft, no 2 setups are the same, each will have differing results.