Osburn 3500 reviews please

[Torgul83]

I'm needing a large insert, 2400sq ft main floor open concept, upstairs is another 1200 sqft. FP is not on exterior wall, about 30ft chimney. I'm tempted by the non cat stoves cause I'm likely the one to be loading it and leaving for work and can't rely on others for bypass business. Not liking the idea about gunking up the cat, maybe I'm over thinking it. I could consider BK if sirocco had a bigger cubic ft box.
Any one out there with comments on the osburn 3500, seems like a hefty straight forward unit. Real life burn times with the damper on low?

 

[begreen]

The 3500 has the same firebox as the big Drolet HT3000. Burntime will be determined by several factors depending on the outside temps, draft strength, heat loss of the house, wood species, air setting, and the operator. In shoulder season a 10-12 hr burn time is not unreasonable to expect, but when it's in the single-digits and the stove is being pushed for heat, then this may drop to 8 hrs. If the fireplace is exterior then installing a block-off plate in the damper area will help deliver more heat into the room.

 

[Torgul83]

The 3500 has the same firebox as the big Drolet freestanders. Burntime will be determined by several factors depending on the outside temps, draft strength, heat loss of the house, wood species, air setting, and the operator. In shoulder season a 10-12 hr burn time is not unreasonable to expect, but when it's in the single-digits and the stove is being pushed for heat, then this may drop to 8 hrs. If the fireplace is exterior then installing a block-off plate in the damper area will help deliver more heat into the room.

That's great information. Yes, if I can get up to 7 hours of useful heat before the blower shuts off with optimal MC fuel in a north eastern January temp, I'd be content.
Wow 10 to 12 hours on a non cat stove is wonderful.
I spoke to an installer who advised against block off plates and recommended Roxul insulation stuffed around the flue (a non combustible insulate).

 

[begreen]

@Solarguy3500 got the 3500 last year. He should have a full season on it by now if he catches this thread.

The installer is taking the lazy route. Roxul will breathe and leak heat up the flue. It's better to put that behind the insert if there is room in the fireplace cavity.

Will the liner at least be insulated? How tall will it be?

 

[stoveliker]

Roxul does not prevent cold air from sinking down (or hot air going up). Hence vapor barriers in insulation using (glass or stone) wool. Thus a block off plate, a seal, and indeed insulated with Roxul, is better.

Also, is your flue liner insulated? A tall chimney will loose a lot of heat before gases exit at the top. You don't want to clog up the top with condensed creosote because it gets too cool.

 

[Torgul83]

@Solarguy3500 got the 3500 last year. He should have a full season on it by now if he catches this thread.

The installer is taking the lazy route. Roxul will breathe and leak heat up the flue. It's better to put that behind the insert if there is room in the fireplace cavity.

Will the liner at least be insulated? How tall will it be?

@Solarguy3500 , I'd love to hear about your experience thus far.
Hmm, I've been told in life to never under estimate peoples laziness and stupidity.
The liner needed is likely 30 ft.
Do you think a block off plate is necessary for an interior wall chimney?
He also mentioned since it is an interior walled chimney, I won't need am insulated liner. If I wanted, I can buy insulation tape and it can wrap the liner before it goes in. I found this unorthodox but what do I know

 

[Torgul83]

Roxul does not prevent cold air from sinking down (or hot air going up). Hence vapor barriers in insulation using (glass or stone) wool. Thus a block off plate, a seal, and indeed insulated with Roxul, is better.

Also, is your flue liner insulated? A tall chimney will loose a lot of heat before gases exit at the top. You don't want to clog up the top with condensed creosote because it gets too cool.

I was told since it is an interior walled chimney, insulated liner is not a must. This is the first I've heard of this.

 

[dafattkidd]

I'm needing a large insert, 2400sq ft main floor open concept, upstairs is another 1200 sqft. FP is not on exterior wall, about 30ft chimney. I'm tempted by the non cat stoves cause I'm likely the one to be loading it and leaving for work and can't rely on others for bypass business. Not liking the idea about gunking up the cat, maybe I'm over thinking it. I could consider BK if sirocco had a bigger cubic ft box.
Any one out there with comments on the osburn 3500, seems like a hefty straight forward unit. Real life burn times with the damper on low?

I have the Osborn 2400i and the Blaze King Ashford insert. These are both cousins of the two units you mentioned. While I am very happy with the Blaze King, I think the Osburn puts out more heat. 2400 sf is a lot to ask of any unit, but I think you’ll do great with either one.

Here’s some input: I find the Osborn firebox accommodates a huge amount of wood almost double what I can fit in the Ashford. The Osburn is a beast of a heater. A full load of well seasoned oak and locust will produce a ton of heat. The heat comes in waves: first 30 minutes heat up, for two-three hours or so of very high stove top temps (500*-700*), the next few hours a slow decline of temp (400*-300*), then it will stay around 300* for a long time with a huge bed of coals. You can reload 8-12 hours later on a large coal bed and restart the process. 300* stove top for a insert is not putting out a ton of heat, but after the 500*-700* temps crank a million BTUs into the house, a few hours of low steady heat is fine.

My Blaze King Ashford is a new unit to me. It operates differently and is installed in a very different house, so it’s not really apples to apples. Hope that’s helpful.

 

[Torgul83]

I have the Osborn 2400i and the Blaze King Ashford insert. These are both cousins of the two units you mentioned. While I am very happy with the Blaze King, I think the Osburn puts out more heat. 2400 sf is a lot to ask of any unit, but I think you’ll do great with either one.

Here’s a comparison: I find the Osborn firebox accommodates a huge amount of wood almost double what I can fit in the Ashford. The Osburn is a beast of a heater. A full load of well seasoned oak and locust will produce a ton of heat. The heat comes in waves: first 30 minutes heat up, for two-three hours or so of very high stove top temps (500*-700*), the next few hours a slow decline of temp (400*-300*), then it will stay around 300* for a long time with a huge bed of coals. You can reload 8-12 hours later on a large coal bed and restart the process. 300* stove top for a insert is not putting out a ton of heat, but after the 500*-700* temps crank a million BTUs into the house, a few hours of low steady heat is fine.

My Blaze King Ashford is a new unit to me and operates differently and is a very different house, so it’s not really apples to apples. Hope that’s helpful.

Very helpful. Thank you.
I imagine as it heats up, you are closing the damper incrementally to bring down the temp for a longer more sustained burn around 300 degrees, correct?

 

[begreen]

@Solarguy3500 , I'd love to hear about your experience thus far.
Hmm, I've been told in life to never under estimate peoples laziness and stupidity.
The liner needed is likely 30 ft.
Do you think a block off plate is necessary for an interior wall chimney?
He also mentioned since it is an interior walled chimney, I won't need am insulated liner. If I wanted, I can buy insulation tape and it can wrap the liner before it goes in. I found this unorthodox but what do I know

For an interior chimney, code requires an insulated liner if the chimney structure does not have 2" clearance from any combustible all the way up through the house and roof. The benefit from a block-off plate is less if the chimney and fireplace are interior, especially if the chimney is exposed on the upper floors.

The 30' liner may be an issue. That is very tall and could be the source of excess draft. I say could be because if this is a basement installation then there may be negative or neutral pressure there. How does the fireplace work now? Does it draft weakly, moderately, or strong? Do you get smoke spillage from it?

 

[dafattkidd]

Very helpful. Thank you.
I imagine as it heats up, you are closing the damper incrementally to bring down the temp for a longer more sustained burn around 300 degrees, correct?

I close the air intake as far as it goes on almost all burns. The unit burns hotter and longer with the air intake shut down.

 

[Torgul83]

For an interior chimney, code requires an insulated liner if the chimney structure does not have 2" clearance from any combustible all the way up through the house and roof. The benefit from a block-off plate is less if the chimney and fireplace are interior, especially if the chimney is exposed on the upper floors.

The 30' liner may be an issue. That is very tall and could be the source of excess draft. I say could be because if this is a basement installation then there may be negative or neutral pressure there. How does the fireplace work now? Does it draft weakly, moderately, or strong? Do you get smoke spillage from it?

It is not a basement installation. It is a main floor FP. It drafts nicely I say, not excessive, pretty darn easy to start a fire now, I'd say moderate. Very little smoke spillage into the room. Would you expect the draft to be excessive in this set up? Are there ways to mitigate this so my draft doesn't kill my burn times?

 

[begreen]

Are there ways to mitigate this so my draft doesn't kill my burn times?

Unfortunately for an insert, the options are more challenging. A good installer may be able to put in a key damper right above the flue collar if there is room. A coupling and extension are devised and a hole is drilled in the surround so that it can be operated.

 

[stoveliker]

I was told since it is an interior walled chimney, insulated liner is not a must. This is the first I've heard of this.

Less of an issue for temps (not for safety clearance, as noted above). But you have to think intemperature differences. Either it's 10 F outside and 350 F in the flue, or it's 70 F outside (i.e. inside room temperature) and 350 in the flue. It's not that big of a difference. Yes it is for us, but for a 350 F flue it's both cold. 340 vs 280 F is the temperature gradient that lets the heat out of the flue.

A tall chimney cools down more.

If safety clearance is met, you can start with the current liner, not insulated, and see how it goes up top.

Do get a flue probe thermometer (not a magnetic one) so you can keep an eye on the flue temps you are putting into the flue and relate that to the observations near the top of possible creosote deposits.

 

[stoveliker]

Hm, a flue probe is hard for an insert.

 

[begreen]

Hm, a flue probe is hard for an insert.

Good case for an Auber AT-100.

 

[Solarguy3500]

@Solarguy3500 got the 3500 last year. He should have a full season on it by now if he catches this thread.

The installer is taking the lazy route. Roxul will breathe and leak heat up the flue. It's better to put that behind the insert if there is room in the fireplace cavity.

Will the liner at least be insulated? How tall will it be?

I did buy the Osburn 3500 insert a year ago, but I actually haven't finished installing it yet.

I started an install thread and got into some of the preliminary design work for my block off plate, etc but I realized that my chimney needed a new crown and some other work. I wasn't able to get that done before this past winter, so the plan is to get it done this summer and have the insert installed and ready for next winter.

 

[ABMax24]

I'd plan on needing a flue damper with that Osburn. I'd also plan on installing some form of flue temperature monitoring device, SBI is now building most of their stoves with either a stainless sheet below the stove top or a C-Cast piece below the stove top (on this model the C-Cast piece) for emissions reductions, but as a side effect reduces heat transfer and increases flue temps.

 

[EbS-P]

My Drolet 1800 insert (2.4 cu ft) I needed a damper on 24’ of insulated liner. I have an Auber at-200 in the appliance adapter (love it!) that is also where I have the damper. And I have the steel plate welded to the top. My flue temps are high. Might even need to block the holes in the damper.

I can get 12 hours with the blower on if I get decent bed of coals and then a full load. I would imagine the bigger firebox could go longer. If I get everything hot. The flue temps are above room temp 24 hours later.

I consider a blockoff plate a must. Ran my stove 2 years without and was doing a good job of heating the attic. As for insulating the liner. Do it to code and be done. If you aren’t sure you are meeting code the. Just add the insulation and be done. Should be 500$ or less to add. (If the flue is big enough. didn’t read close enough, my apologies).

Evan

 

[nihilomni]

@Solarguy3500 , I'd love to hear about your experience thus far.
Hmm, I've been told in life to never under estimate peoples laziness and stupidity.
The liner needed is likely 30 ft.
Do you think a block off plate is necessary for an interior wall chimney?
He also mentioned since it is an interior walled chimney, I won't need am insulated liner. If I wanted, I can buy insulation tape and it can wrap the liner before it goes in. I found this unorthodox but what do I know

Hey Torgul83! I hope your osburn 3500 is running well. I am in a very similar situation with a 6400sqft home, and fireplace on the middle floor. Its about 30ft of liner I will need to install. Did you have to install a flue damper, if not, do you feel like you need one? I was planning on installing the osburn 3500 as well unless someone else can recommend something else..

Thanks.

 

[Torgul83]

Hey Torgul83! I hope your osburn 3500 is running well. I am in a very similar situation with a 6400sqft home, and fireplace on the middle floor. Its about 30ft of liner I will need to install. Did you have to install a flue damper, if not, do you feel like you need one? I was planning on installing the osburn 3500 as well unless someone else can recommend something else..

Thanks.

Hey there! I wish I could tell you how it's been working but the weather is still pretty hot here in Upstate, NY. So it turns out my flue is 24 feet. I Over estimated the height cause I'm bad at these things. So I did not go with a flue damper because A) it's a little trickier with the insert u less one can macguiver something that you access by drilling a hole through the surround and B) I felt at 24 feet I could live with slight overdraft. I did some test burns and it was so cool to see the re-burn on the baffles, its really a cool unit. The fire box is huge, I can fit 24 inch logs diagonally easily.

 

[stoveliker]

What a great install is that!

 

[Torgul83]

What a great install is that!

Thank you

 

[Torgul83]

So this is the family room, the first floor is roughly 2000 sqft but as u can see it is relatively an open concept. The family room has vaulted 12-14ft ceiling and the family room is slightly sunk in compared to the rest of the first floor which has standard roughly 9-10 foot ceiling. I'm hoping that the sunken family room allows the hot air to just make its way up to the rest of the 1st floor provided I get some good circulation of air with fans pointing towards the stove.

 

[stoveliker]

Run those fans on their lowest setting. Quiet, and you don't want to mess up the stratification of the warm and colder air when using fans this way.