Rear flue exit VS Top flue exit

[frankm1960]

Yes that makes sense. I may haul the stove out again and seal the block off plate with some sealant. I may have been a bit sloppy installing that block off plate.

 

[BrotherBart]

Yeah nothing is going to give more radiant heat from something that isn't sitting out in the room. The idea of the block off plate with an insert is hotter air coming out of the shroud when the blower is running. An insert will never be a radiant heater. No more than my freestanding stove inside a fireplace will.

 

[frankm1960]

You just gave me an idea. Why couldn't I haul the insert out of the fireplace and set it into the room just like a free standing stove ? I would have to modify the front of the fire place and add a bit of pipe but I would have to do all that to install a regular free standing wood stove anyway. Maybe I'd get more radiant heat from the stove and possibly not even have to replace it. Any thoughts on this idea ?

 

[Grisu]

You just gave me an idea. Why couldn't I haul the insert out of the fireplace and set it into the room just like a free standing stove ? I would have to modify the front of the fire place and add a bit of pipe but I would have to do all that to install a regular free standing wood stove anyway. Maybe I'd get more radiant heat from the stove and possibly not even have to replace it. Any thoughts on this idea ?

That would void the UL listing of the insert and you would need to install it with all clearances for an unlisted stove. Also you would need quite a bit of r-value in the hearth as the insert is designed to sit in a masonry structure, not on combustibles.

Is that fireplace on an exterior or interior wall? What brand/model is it? What kind of wood are you burning and how long has it been seasoned? When you turn on your furnace/boiler/whatever, how long does it take to get the home warm?

 

[BrotherBart]

Rather than do that, just try taking the surround off of it where it is at.

 

[frankm1960]

That would void the UL listing of the insert and you would need to install it with all clearances for an unlisted stove. Also you would need quite a bit of r-value in the hearth as the insert is designed to sit in a masonry structure, not on combustibles.

Is that fireplace on an exterior or interior wall? What brand/model is it? What kind of wood are you burning and how long has it been seasoned? When you turn on your furnace/boiler/whatever, how long does it take to get the home warm?

It's on an exterior wall. Can't remember the model or brand, label is on the back side. I'm burning softwood at the moment which I'm told has been cut sept 2013 so it's about 1yr drying outside. Its takes hours to heat the house up a couple degrees which is why I'm looking to change things to get more heat. It may be that the insert is just to small. It holds 20" sticks so the fire box isn't tiny by any means. Here's some pix.

 

[frankm1960]

Rather than do that, just try taking the surround off of it where it is at.

That's a lot of bricks to remove. I'd rather not do that unless I remove the whole fireplace and chimney which I've considered doing. Check out the pix above if you have time. My set up is shown in my avitar as well. It's a basic fireplace from the 70's, standard split entry home roughly 25' x 45' which is now opened up somewhat ie kitchen/dining/living room area is pretty much one big room roughly 25' x 30' I'd say, which is the area I want to heat. The bedrooms will take a long time to get warmer but they will eventually. I'm not trying to heat the basement with wood, I leave that fairly cold.

 

[Grisu]

It's on an exterior wall. Can't remember the model or brand, label is on the back side. I'm burning softwood at the moment which I'm told has been cut sept 2013 so it's about 1yr drying outside. Its takes hours to heat the house up a couple degrees which is why I'm looking to change things to get more heat. It may be that the insert is just to small. It holds 20" sticks so the fire box isn't tiny by any means.

When it is at an exterior wall you may loose heat through the bricks out the back. If you have some room, try insulating behind the insert. See this thread: https://www.hearth.com/talk/threads/finally-got-around-to-insulating-my-fireplace.75755/

Has the wood been split after cutting or was it just split recently? Unsplit wood barely dries, you may be burning green wood. Did you check its moisture content? If it was split: In my experience softwood likes to soak up water. Has the wood been top-covered during the seasoning?
How far do you reduce the air when you burn the wood? Do you have a way of measuring the temps of the insert (stove thermometer)?

That's a lot of bricks to remove. I'd rather not do that unless I remove the whole fireplace and chimney which I've considered doing.

The surround is the black metal plate that covers the fireplace opening. When you remove that one you will see the insert sitting in the fireplace.

 

[mellow]

That is what I was going to recommend, insulating the entire firebox as it sounds like you are losing heat to the outside with an exterior fireplace, I would at a minimum insulate the firebox behind the insert with Roxul, but Roxul and Cement board works better. I saw a difference in my burn times and heat coming out of the insert after insulating the entire firebox.

Just think about it, all that heat has to warm the surrounding brick before it will start putting it out via the fan.

 

[frankm1960]

When it is at an exterior wall you may loose heat through the bricks out the back. If you have some room, try insulating behind the insert. See this thread: https://www.hearth.com/talk/threads/finally-got-around-to-insulating-my-fireplace.75755/

Has the wood been split after cutting or was it just split recently? Unsplit wood barely dries, you may be burning green wood. Did you check its moisture content? If it was split: In my experience softwood likes to soak up water. Has the wood been top-covered during the seasoning?
How far do you reduce the air when you burn the wood? Do you have a way of measuring the temps of the insert (stove thermometer)?


The surround is the black metal plate that covers the fireplace opening. When you remove that one you will see the insert sitting in the fireplace.

About 2/3 was already split, 1/3 was split in may. I'm not confident that the stuff I split was cut in sept 2013 but he said it was. It's all been stacked and top covered outside drying since first of May. I didn't check it's moisture content.

I do have some wood that was cut and split in spring 2013 which I'll try in a few days to see it that's better. It was stacked in a "garage in a box" type shelter without a door so I think it would be more dry.
Today I did not reduce the air at all, in fact I kept the door open a crack because I saw smoke from the chimney when I closed the door. Smoke from the chimney indicates low temp burn ?? so I kept the door open a bit and saw more flames and that eliminated the smoke from the chimney. I don't have a stove thermometer.

 

[frankm1960]

That is what I was going to recommend, insulating the entire firebox as it sounds like you are losing heat to the outside with an exterior fireplace, I would at a minimum insulate the firebox behind the insert with Roxul, but Roxul and Cement board works better. I saw a difference in my burn times and heat coming out of the insert after insulating the entire firebox.

Just think about it, all that heat has to warm the surrounding brick before it will start putting it out via the fan.

Thank you for that info. It's good to hear from others who have already been there and done that. I'll give that a shot as soon as my stove cools. I do have some "attic roxul" but I don't know if that will stay in place as well as the roxul board type stuff.

 

[Grisu]

Smoke from the chimney indicates wet wood. You should only see some during the startup phase, like the first 10 minutes of a burn. Leaving the door open means you operated the insert as a fireplace; essentially sending most/all of the heat up the chimney. I would get a stove thermometer to check if you even get the insert up to temp. Invest also in a moisture meter to check your wood. I have the feeling you are having still wet wood and to compensate for that you leave the air open too far sending most of the heat up the chimney. Your insert may rarely reach optimal burning temps and therefore cannot heat your home.

 

[frankm1960]

Rather than do that, just try taking the surround off of it where it is at.

I completely miss understood. I have had the insert out before and I may leave the shroud off when I remove the insert to insulate behind it. Thanks for that tip. It's gonna look some ugly without the shroud. The bricks behind it are kinda black. Maybe I can clean them I don't know.

 

[frankm1960]

Smoke from the chimney indicates wet wood. You should only see some during the startup phase, like the first 10 minutes of a burn. Leaving the door open means you operated the insert as a fireplace; essentially sending most/all of the heat up the chimney. I would get a stove thermometer to check if you even get the insert up to temp. Invest also in a moisture meter to check your wood. I have the feeling you are having still wet wood and to compensate for that you leave the air open too far sending most of the heat up the chimney. Your insert may rarely reach optimal burning temps and therefore cannot heat your home.

I left it open about a 1/4" , not much but I hear what you're saying. I shouldn't have to leave it open at all if the wood is dry, in fact I should be able to close off the draft a bit after it's been going a while.
I will try my other load of wood and will invest in a stove thermometer if I see the same burn issues with that batch of wood.
Roughly what should the temp be at the top of my insert?

 

[begreen]

The top of the insert is not the stove top. There is a convection air space below the top so readings on it would be low. Measure the stove temp on the face above the left or right side of the door. It should read about 500-600F with a good fire going.

 

[Grisu]

I left it open about a 1/4" , not much but I hear what you're saying. I shouldn't have to leave it open at all if the wood is dry, in fact I should be able to close off the draft a bit after it's been going a while.
I will try my other load of wood and will invest in a stove thermometer if I see the same burn issues with that batch of wood.
Roughly what should the temp be at the top of my insert?

I can tell you what I did. First, I got an IR thermometer ($30 at Harbor Freight); not just for the stove but also to check for cold spots in the house. Then I pulled off the surround of the insert, removed the top of the air channel to expose the actual stove top. That is the part where the warm air comes out in your case. For a few days I fired the insert as usual some times with the blower off, some times on. I measured the hottest spot on the stove top and then also the hottest spot on the front of the insert which in my case is directly above the door in the center. At the beginning of the burn the difference was usually ~100 F less in the front than on the top, later when the secondaries have been on for a while and the stove had settled in for a nice burn more like 50 F less. Then I put everything back together and now I know that measuring the spot in the front means 50 to 100 F less than the stove top. Thus I aim for 600 F to 650 F max at that location, translating to around 650 F to 750 F stove top depending on the stage of the burn cycle.

If you get a typical stove thermometer (Condar is preferred here) use it as BeGreen suggested. And maybe test your stove also with some kiln-dried wood from the store or some lumber scraps. Essentially any wood you know is surely dry.

 

[frankm1960]

The top of the insert is not the stove top. There is a convection air space below the top so readings on it would be low. Measure the stove temp on the face above the left or right side of the door. It should read about 500-600F with a good fire going.

Yes, good point. I do have a convection/duct around the bottom, back and top which is used by the blower. I believe the blower pulls the air from the room, forces it around and out the top duct, heating up as it goes around the hot stove. As you say I should put the thermometer at the front where there's space. The top of my stove would definitely be much cooler I would say.

 

[frankm1960]

I can tell you what I did. First, I got an IR thermometer ($30 at Harbor Freight); not just for the stove but also to check for cold spots in the house. Then I pulled off the surround of the insert, removed the top of the air channel to expose the actual stove top. That is the part where the warm air comes out in your case. For a few days I fired the insert as usual some times with the blower off, some times on. I measured the hottest spot on the stove top and then also the hottest spot on the front of the insert which in my case is directly above the door in the center. At the beginning of the burn the difference was usually ~100 F less in the front than on the top, later when the secondaries have been on for a while and the stove had settled in for a nice burn more like 50 F less. Then I put everything back together and now I know that measuring the spot in the front means 50 to 100 F less than the stove top. Thus I aim for 600 F to 650 F max at that location, translating to around 650 F to 750 F stove top depending on the stage of the burn cycle.

If you get a typical stove thermometer (Condar is preferred here) use it as BeGreen suggested. And maybe test your stove also with some kiln-dried wood from the store or some lumber scraps. Essentially any wood you know is surely dry.

I've been looking on ebay for an IR thermometer. I saw another thread in here on that. I'll check my stove and see if I can access the top of mine. I don't think I can remove the top of the air channel though. I've had that stove out back in the spring and didn't see anything. But I will be taking it out to insulate the fireplace behind the stove.

I did do a burn today (still going right now) and used the other batch of wood and there was a big difference. I didn't need to leave the door open and I currently have the draft shut down and it's burning fine and there is slightly hotter air coming from the convection air space and the wood is burning slower but still burning. So there's a lesson learned on green wood. I thought that batch of wood I got was dry enough but I think that guy I got it from let it sit out all winter before he split it , at least some of it he did I'm sure. I'll burn that batch next year. I have another batch here that was split and stacked and covered back in may 2013 so I'm going to use that up this winter.

I do need to get that IR thermometer though. Take some of the guess work out while I get more experience. I'm hoping to start cutting my own wood so that should take some guess work out of the wood I burn, down the road at least.

 

[frankm1960]

Ok so I got the stove out and modified the fireplace by removing the base (which was sticking out into the room and not big enough to be useful and more in the way) right down to the floor.
As a test I want to install the stove outside the fireplace just like any other stand alone wood stove. It's not designed for that but I want to fire it up and see if the stove radiates heat. Currently the stove doesn't radiate heat hardly and I want to know if its the stove or the fact the stove sits in a masonary fireplace. I've done a block off plate but have yet to insulate behind the stove but I may do that depending on my findings.

So, before I do this I need to build a hearth. I checked the hearth building guide on this site. This stove is designed to sit in a fire place so there's no R value specified for a hearth so I need to pick one.
I'll pick R=3 (very high) which is roughly a 2" ventilated air gap. I'll build a 4' x 8' ceramic tile on plywood hearth which I'll set in front of the fireplace right on the floor you se. On top of the plywood and ceramic hearth I'll put 4 bricks on the flat as "legs" and set the stove on that. This raised the stove up 2" and should give me my R value 3. If you notice the stove has almost a 4" air gap on the bottom as well ( the duct for the blower) so I almost think I could set the stove directly on the ceramic tile hearth but I'll maintain that 2" air gap to make sure.

Here are some pics.

Any comments on this other than the fact it's against the code. I'm only doing this temporarily until the "test" is done.

Thanks,
Frank

 

[bholler]

I am sorry but putting it up on bricks does not give you any r value it is very dangerous to do so and you should not do it. You need a hearth board or many layers of durarock next gen or micore of something with a given insulating value. Just air space does not work. DO NOT BURN IT THE WAY YOU ARE PROPOSING.

 

[frankm1960]

I am sorry but putting it up on bricks does not give you any r value it is very dangerous to do so and you should not do it. You need a hearth board or many layers of durarock next gen or micore of something with a given insulating value. Just air space does not work. DO NOT BURN IT THE WAY YOU ARE PROPOSING.

Thanks for commenting. Sorry I should have said I wasn't going to fire up the stove until I've heard comments from others. My last post was just me thinking "out loud" more than anything. I didn't mean to scare anyone. I'm feeling out my options and looking for input from others in the know.

I have read the hearth building article published on this forum and from the common materials R value chart I see that a 1" ventilated air space gives an R value of 1.43. One layer of 1/2" durarock gives an R value of 0.26. The way I interpret that is that I would need almost 6 layers of 1/2" durarock to give the same R value as a 1" ventilated air space. My interpretation of a ventilated air space is just a space where air can easily circulate. What am I misinterpreting here ?

I'm surprised that an air space of one inch has such a high R value considering a one inch granite slab only has an R value of .083. Air it seems has a relatively high R value according to this chart. Air has almost 3x the R value of durarock.

 

[begreen]

I am sorry but putting it up on bricks does not give you any r value it is very dangerous to do so and you should not do it. You need a hearth board or many layers of durarock next gen or micore of something with a given insulating value. Just air space does not work. DO NOT BURN IT THE WAY YOU ARE PROPOSING.

This is completely incorrect. 3/8" millboard is a fairly mild requirement. I think 1/2" Durock NexGen is about equivalent. You can no longer get regular Durock cement board (R value .26 per 1/2") Durock NexGen has replaced it, R=.39 per 1/2". Also note that bricks do have an R-value. Common brick is R=.45 for 2 1/4" thickness. And air is an excellent insulator. That is why it is used in an NFPA 211 wall shield.

For more info on the millboard requirement here is a good, old discussion:
https://www.hearth.com/talk/threads/anyone-know-the-r-value-of-metal-clad-millboard.7102/

 

[frankm1960]

This is completely incorrect. 3/8" millboard is a fairly mild requirement. I think 1/2" Durock NexGen is about equivalent. You can no longer get regular Durock cement board (R value .26 per 1/2") Durock NexGen has replaced it, R=.39 per 1/2". Also note that bricks do have an R-value. Common brick is R=.45 for 2 1/4" thickness. And air is an excellent insulator. That is why it is used in an NFPA 211 wall shield.

For more info on the millboard requirement here is a good, old discussion:
https://www.hearth.com/talk/threads/anyone-know-the-r-value-of-metal-clad-millboard.7102/

I'm not sure I understand your comment... what is incorrect in his comment and what do you mean "3/8 millboard is a fairly mild requirement" ... in the context of what we were talking about ?

On another note, I'm amazed that 3 layers of brick have less R value than a 1" air space and if you filled that air space with fibre glass insulation you would more than double the R value of 3 bricks. Would need 3 layers of micore, over 8 sheets of Durock NexGen. Air space and/or insulation (roxul) is probably the best bang for your buck when it comes to building a hearth... if you could find a way to incorporate that into the design. Unless I'm misunderstanding the table.

My insert has a 4" ventilated air space built in on the bottom and 1" on the back and top. Only the sides are without a built in ventilated air space. Maybe that's why it doesn't throw any heat.

Any comments would be greatly appreciated.

 

[begreen]

The pictures show the hearth step removed, but the fireplace hearth intact. Has that changed. The posting says, "As a test I want to install the stove outside the fireplace..." Has that changed or is the insert still going into the fireplace? If in the fireplace then the only concern is the hearth in front of it. This is helped by the 6" rise of the hearth floor above the hearth step. The ash lip and step height helps lower heat radiated downward. According to the label, the insert only requires a millboard hearth. A layer of Durock and brick should be sufficient hearth to be quite safe in this circumstance.

 

[frankm1960]

The pictures show the hearth step removed, but the fireplace hearth intact. Has that changed. The posting says, "As a test I want to install the stove outside the fireplace..." Has that changed or is the insert still going into the fireplace? If in the fireplace then the only concern is the hearth in front of it. This is helped by the 6" rise of the hearth floor above the hearth step. The ash lip and step height helps lower heat radiated downward. According to the label, the insert only requires a millboard hearth. A layer of Durock and brick should be sufficient hearth to be quite safe in this circumstance.

The hearth step was removed and will stay that way. The fire place is still intact and will stay that way. I want to install the stove outside of the fireplace and set it on a large flat 4' x 8' x 2.5" hearth pad (not built yet). The hearth pad will replace the hearth step that I removed and it will sit right in front of the fireplace. I'll set the stove on 1/2" legs of some sort to get an air gap under it. I've reconfigured the stove pipe to accommodate the stove in this position. All I have to do is build the hearth pad and then re-install everything and I'll be ready for the test.

What I do after that will depend on how the test goes.

This is all just a tentative plan. I may or may not go through with it. I may just go straight to a stand alone wood stove but we'll see.

Any thoughts/comments/criticism on that plan are more than welcome