New stove and new to wood stoves

[1750]

We have a new Lopi 1750 (installed in January) and really love the warmth and watching the fire. I've got a couple of questions I hoped someone might have some thoughts about.

1. This stove has a thermostatically controlled blower, but it can take hours before the blower kicks on. I think this is because the outside air kit keeps the pedestal very cool, and the space in back and sides of this stove doesn't warm sufficiently because of heat shields. Any ideas about getting this to kick on more easily? (I've thought about surgery to remove the thermostat, but that's a last resort.)

2. This is a double-walled, straight-up chimney installation. Last night it was terrifically windy. For the first time, I noticed smoke puffing out the bottom of the double-wall, just above the point where the pipe connects to the firebox (the double wall starts about 2 inches above the top of the stove). I was really concerned about this. Can anyone tell me what's happening here?

Thanks in advance for any suggestions you might be ale to provide here!

Mike

 

[begreen]

Welcome Mike. It could be that the stove is not getting hot enough. Is there a thermometer on the stovetop? If so, what's the stove top temp running at?

If the stove is not getting hot enough, it could be weak draft. How tall is the flue from stove top to the chimney cap? Ideally it would be 15' or greater.

 

[Jon1270]

. I think this is because the outside air kit keeps the pedestal very cool, and the space in back and sides of this stove doesn't warm sufficiently because of heat shields.

All that matters is where the thermostatic switch (probably looks like this) is located. It's responding to temperature in a very specific place, not several places. On my insert this switch is just below the firebox. I'm fairly sure they put it there because this type of inexpensive switch can't tolerate the much higher temperatures up on top of the firebox, where the switch or sensor would be in an ideal world. For the same reason, I expect that's where it is on most stoves. But there's a significant downside in putting it there: the switch only heats up enough to turn the fan on after the firebrick lining the bottom of the stove heats up, which takes awhile in the best of circumstances. Ash is a fantastic insulator, so if you start a new fire on top of a thick bed of cold ashes, it will take that much longer for the bottom of the stove to heat up and finally activate the switch. As the stove cools down at the end of the burn cycle, the firebrick, still insulated by ash, tends to stay warm and thus keep the fan running for a long time after the top of the firebox has cooled to the point that the fan really isn't doing anything useful.

 

[jeff_t]

The fortunate thing about that snap disc is that it is really easy to bypass. The unfortunate thing is that the blower won't shut off if your stove goes cold frequently. That doesn't happen here, and if the weather is warm enough that I'm going to let the fire go out, I'm not using the blower anyway.

 

[1750]

Welcome Mike. It could be that the stove is not getting hot enough. Is there a thermometer on the stovetop? If so, what's the stove top temp running at?

If the stove is not getting hot enough, it could be weak draft. How tall is the flue from stove top to the chimney cap? Ideally it would be 15' or greater.

Thank you for the welcome, begreen. Thanks also for replying. The stove seems to get quite hot. (I have one of those magnetic thermometers on the chimney -- but didn't realize they were only for single-wall pipe!) The pipe comes straight out of the top through the roof, with about 4 feet outside. It's about 10 ft to the ceiling, through the 2x12 and sheathing, and then 3-4 feet outside. I would say it's probably about 15' but maybe not quite. I'll measure it the next time I'm there.

With the exception of the single time we had smoke coming out of the bottom of the double walled pipe (which I wrote about previously), I've never thought draft issues were the culprit.

All that matters is where the thermostatic switch (probably looks like this) is located. It's responding to temperature in a very specific place, not several places. On my insert this switch is just below the firebox. I'm fairly sure they put it there because this type of inexpensive switch can't tolerate the much higher temperatures up on top of the firebox, where the switch or sensor would be in an ideal world. For the same reason, I expect that's where it is on most stoves. But there's a significant downside in putting it there: the switch only heats up enough to turn the fan on after the firebrick lining the bottom of the stove heats up, which takes awhile in the best of circumstances. Ash is a fantastic insulator, so if you start a new fire on top of a thick bed of cold ashes, it will take that much longer for the bottom of the stove to heat up and finally activate the switch. As the stove cools down at the end of the burn cycle, the firebrick, still insulated by ash, tends to stay warm and thus keep the fan running for a long time after the top of the firebox has cooled to the point that the fan really isn't doing anything useful.

Thanks, Jon. I suspect you are right, that the placement of the thermostat is the problem. It's on a very short cord out of the blower on the back, and there isn't really any place to set it. The OAK pulls the OA into the pedestal, and keeps that whole area really, really cold. And, as you note, I've woken in the morning and had the blower pushing cold air around.

The fortunate thing about that snap disc is that it is really easy to bypass. The unfortunate thing is that the blower won't shut off if your stove goes cold frequently. That doesn't happen here, and if the weather is warm enough that I'm going to let the fire go out, and I'm not using the blower anyway.

Thanks, Jeff. I might ask you for guidance on bypass if it comes to that. I'm with you, once it's lit, it stays lit. It's the only heat we use in a cottage, and it would be so much nicer to get the blower working sooner to push the cold room air through the stove to warm things up!

I really appreciate everyone's responses. Does anyone have a thought about the smoke puffing pack out the double-walled pipe right above the stove? It's only happened the one time when it was really windy, but I don't even understand how it would get there.

Thanks!

 

[Jon1270]

Does anyone have a thought about the smoke puffing pack out the double-walled pipe right above the stove? It's only happened the one time when it was really windy, but I don't even understand how it would get there.

That joint isn't sealed (I'm assuming) with any sort of sealant / caulk / cement / etc. Smoke normally stays inside the pipe because the chimney's draft keeps the air pressure inside the chimney lower than the air pressure outside of it, i.e. anywhere there's a small leak, air is getting sucked in, not pushed out. But that system isn't bulletproof. If a gust of wind is somehow directed down into the chimney, that can raise the pressure inside it enough to force smoke out where it isn't supposed to go. Or, the draft if the spark arrestor screen at the top gets clogged with creosote from burning damp wood, or if the chimney isn't tall enough, draft won't be as strong as it should be.

 

[1750]

That joint isn't sealed (I'm assuming) with any sort of sealant / caulk / cement / etc. Smoke normally stays inside the pipe because the chimney's draft keeps the air pressure inside the chimney lower than the air pressure outside of it, i.e. anywhere there's a small leak, air is getting sucked in, not pushed out. But that system isn't bulletproof. If a gust of wind is somehow directed down into the chimney, that can raise the pressure inside it enough to force smoke out where it isn't supposed to go. Or, the draft if the spark arrestor screen at the top gets clogged with creosote from burning damp wood, or if the chimney isn't tall enough, draft won't be as strong as it should be.

Yes, it's actually not sealed at all -- the outer pipe wall starts about two inches above the stove top. Is the gap at the top of the stove pipe (between the inner and outer layers) typically open? I guess I thought there would be a cap at the top that would protect it from sparks and down drafting. But, maybe that's not the case.

Just so I'm clear, are you saying this is a "normal" event, and not an indication of a problem (other than if the chimney's not tall enough). It doesn't represent some sort of installation problem, or anything like that?

Thanks again.

 

[jeff_t]

Yes, it's actually not sealed at all -- the outer pipe wall starts about two inches above the stove top. Is the gap at the top of the stove pipe (between the inner and outer layers) typically open?

Something doesn't sound right. Can you post a pic?

 

[Slow1]

Smoke in the house from the stove (particularly from pipe joints) should not be considered "normal" in any installation. That doesn't mean it doesn't happen of course. I have occasionally had a bit of smoke in the house - but generally only when opening the door and reloading. Even in strong winds, the most I've seen is the draft changes visibly affecting the fire in the box (really strong winds).

I'm curious about this section of your pipe etc - can you post pictures of what is there? You mention it "puffing" from there - was it in sync with gusts of wind (may support the idea of a downdraft in the chimney caused by wind).

Have you ever had smoke smells from this stove before (that were not readily explained by door opening etc)?

As to stove temps - you say it gets 'quite hot' on the surface of your double-wall pipe - what temperatures are you reading there (and how high up from the stove is the thermometer)? It seems that "hot" and "quite hot" are rather subjective terms...

 

[begreen]

There should be no air getting in between the stove and the pipe. Can you post a couple pictures of the setup and maybe a close up of the stove flue collar area? Put the thermometer on the stove and let us know what temps you are reading at various stages of combustion.

Are you closing the bypass after the fire is going well, then incrementally reducing the air supply via the air control?

 

[1750]

Something doesn't sound right. Can you post a pic?

I don't think I have a pic of this. It's at a cottage, so I'll have to get one the next time I'm there.

Smoke in the house from the stove (particularly from pipe joints) should not be considered "normal" in any installation. That doesn't mean it doesn't happen of course. I have occasionally had a bit of smoke in the house - but generally only when opening the door and reloading. Even in strong winds, the most I've seen is the draft changes visibly affecting the fire in the box (really strong winds).

I'm curious about this section of your pipe etc - can you post pictures of what is there? You mention it "puffing" from there - was it in sync with gusts of wind (may support the idea of a downdraft in the chimney caused by wind).

Have you ever had smoke smells from this stove before (that were not readily explained by door opening etc)?

As to stove temps - you say it gets 'quite hot' on the surface of your double-wall pipe - what temperatures are you reading there (and how high up from the stove is the thermometer)? It seems that "hot" and "quite hot" are rather subjective terms...

I'll post a pic if I can find one, or get one if I can't.

The puffs were definitely in sync with the gusting. I've never had any trouble with smoke that wasn't explained by opening the door. The magnetic thermometer is placed about a foot above the top (which is what the directions prescribed) and hardly gets above 250F on the outside of the double wall pipe... that's why I was looking for a conversion. I don't think I've ever used it on the top of the firebox. I'll do that the next time I fire it up. I realize "hot" and "quite hot" are pretty subjective. The stove seems to heat very well. It lights easily and stays lit. It will heat a large (~ 600 sqft) open room with vaulted ceiling to 70+. When I pack it full before going to bed it lasts the night dampered all the way down and loses maybe two degrees.

I've never had issues with smoke previously unless the door is open. This is new construction, and the house is quite tight. If it matters, we had an OAK installed, as well.

There should be no air getting in between the stove and the pipe. Can you post a couple pictures of the setup and maybe a close up of the stove flue collar area? Put the thermometer on the stove and let us know what temps you are reading at various stages of combustion.

Are you closing the bypass after the fire is going well, then incrementally reducing the air supply via the air control?

There is no gap between the inside stove pipe and the stove, but the outside pipe of the double wall starts an inch or two above the top. I'll post a picture when I have one.

I'm pretty sure this stove doesn't have a bypass. The only control is the air control on the front.

Thanks to everyone for your thoughts on this. I'll post some pictures and take some temperatures as soon as I can!

Mike

 

[begreen]

The heat ranges (hot, too hot) are for single wall flue temps. You can ignore them for the stove top temps and just use the actual temperature readings. Place it on the stove top and not the convective lid. It could be that you had the fire throttled down a bit early and it was smoking. This is easier to do if the wood is not fully seasoned and dry. With marginal draft and a strong wind you can get a bit of a puff back. Adding a couple feet of chimney if this is the case, can make a nice difference. Brace the chimney at the 5' level if this is done.

Or it could be the cabin is in a particularly windy area where the wind is tunneled toward the roof. Is the chimney higher than the roof ridgeline? Chimney location can sometime be affected by location. Here's an illustration of some location issues.



Also, make sure your chimney honors the 10-3-2 rule.

 

[1750]

The heat ranges (hot, too hot) are for single wall flue temps. You can ignore them for the stove top temps and just use the actual temperature readings. Place it on the stove top and not the convective lid. It could be that you had the fire throttled down a bit early and it was smoking. This is easier to do if the wood is not fully seasoned and dry. With marginal draft and a strong wind you can get a bit of a puff back. Adding a couple feet of chimney if this is the case, can make a nice difference. Brace the chimney at the 5' level if this is done.

Or it could be the cabin is in a particularly windy area where the wind is tunneled toward the roof. Is the chimney higher than the roof ridgeline? Chimney location can sometime be affected by location. Here's an illustration of some location issues.

View attachment 100319

Also, make sure your chimney honors the 10-3-2 rule.

View attachment 100320

Wow, those are great illustrations!

Our chimney is on an outside wall, but nowhere near being higher than the ridge. I think it conforms to the 10-3-2 rule, but it would have to be another 10-12 ft high to be above the ridgeline. The good news, I guess, is that is on the windward side of the house, and the wind coming off of the lake is pretty steady and predictable under most circumstances (unlike the other night!).

Thanks again!

 

[begreen]

The top of the pipe doesn't have to be above the ridgeline as long as it is 2 ft higher than any building point (roof in your case) within a 10 ft radius.

 

[Ram 1500 with an axe...]

I would call lopi and get an answer about what is the norm for the fan to turn on. Something can't be right if it takes hours. My montpelier takes 38-45 minutes to turn on, It is very consistent with how fast and how hot I can get the stove when starting from scratch. These new stoves should work correctly or there is an issue. I have not had any back smoke, luckily, I think it's because I used heat tape at all the connections to ensure no leakage, you may want to try that. Good luck.

 

[1750]

I would call lopi and get an answer about what is the norm for the fan to turn on. Something can't be right if it takes hours. My montpelier takes 38-45 minutes to turn on, It is very consistent with how fast and how hot I can get the stove when starting from scratch. These new stoves should work correctly or there is an issue. I have not had any back smoke, luckily, I think it's because I used heat tape at all the connections to ensure no leakage, you may want to try that. Good luck.

Thanks, Ram 1500... I've got a call in to the guy I bought it from. He's an old installer, so I think/hope he'll know if it was done right and or if there is a problem with the controller.

I really think it's the cold air coming in from the OAK that keeps the pedestal very chilly that is my problem here. I'll be interested in what the Lopi dealer says about it.

Thanks again.

 

[1750]

The top of the pipe doesn't have to be above the ridgeline as long as it is 2 ft higher than any building point (roof in your case) within a 10 ft radius.

I think it meets that standard. If not, it's very close. I'll check the next time I'm up.

I found a picture of the set-up. It's not very high-resolution, but you should be able to see what I'm talking about.
The double wall doesn't start until 2-3 inches off of the top of the stove. It's just a bit below the line where the slate ends in back of the stove. That's where the smoke was puffing out when the wind was blowing. You can also see the OAK supply from outside. The pedestal stays understandably frigid, and I think is probably what keeps the blower thermostat from kicking in, but that's just a guess.


Thanks again to all of you for your input.

 

[begreen]

Next time you are up there take a look at the blower's thermostatic snap switch. Usually there is a spring steel piece that presses it against the stove. Try to increase the pressure on the switch by rebending the spring if you find the snap switch loose.

Also, do you see good secondary combustion from the burn tubes in the earlier stage of burning? How dry is the wood you are burning?

 

[1750]

Next time you are up there take a look at the blower's thermostatic snap switch. Usually there is a spring steel piece that presses it against the stove. Try to increase the pressure on the switch by rebending the spring if you find the snap switch loose.

Also, do you see good secondary combustion from the burn tubes in the earlier stage of burning? How dry is the wood you are burning?

The thermostat is not attached to the stove. It just came as a separate unit that's apparently supposed to sit on the floor. The cord from the blower to the control is so short it can't even be mounted to the wall in back of the stove. I am trying to find a way to attach it to the heat shield that will keep it off the pedestal base -- right now I just have it resting on a log.

I see fire coming out of the tubes... I'm assuming that's secondary combustion (I'm admittedly ignorant of most of this), but it doesn't seem to appear until the fire is really cooking. I think the wood could be drier. I bought this load from a local who keeps it tarped, but I don't know how long it's been split.

Can you see the double walled pipe starting a couple of inches above the base? Does that seem legit?

Thanks again.

 

[begreen]

That doesn't sound right, the blower switch is free floating, but the blower thermostat is mounted on the stove body. To see what I am talking about, go to page 35 of your manual.


I do see the pipe and it too looks odd. Mine is nothing like that.

 

[1750]

That doesn't sound right. We'll need to see some shots of this. Is it supposed to be a factory unit?

I do see the pipe and it too looks odd. Mine is nothing like that.

Yes, it's supposed to be a factory unit. It came in the box from the retailer.

I've got a call in to the store, and expect to talk with the salesman tomorrow.

 

[begreen]

Read the manual, page 35.

 

[1750]

Read the manual, page 35.

I just found it on the Travis site.

I don't think this is the same manual that I have (I don't remember the section on the snap switch), but I'll print these pages up and take them with me.

I assumed the thermostat was in the controller with the rheostat; I'd never heard of this snap switch until you mentioned it earlier.

If this works the way it seems in the diagram (the snap switch is the thermostat, right?), then I bet you are right, that it might not be in contact with the floor of the fire box.

I'm excited to go take a look at it. Thanks a lot for pointing out that page in the manual to me (I've read the manual, though maybe just read through the blower entry and not this bit at the end).

Regardless, I really appreciate your time and help with this!

 

[Jon1270]

(the snap switch is the thermostat, right?)

Yep. And it makes no sense for it to be sitting on the floor. The cord is short because it only needs to be long enough that you can pull it out for maintenance.

 

[begreen]

I think the part sitting on the floor is the rheostat/switch box. The thermostat should be on the underside of the stove. Follow the wires with the stove blower unplugged.

Note that even with greater tension on the snap disk spring, the fan will take a while to come on the first time. Once the stove body is thoroughly warmed up, it should then stay on.