Repurposing the existing smoke chamber

Wood recycler · Nov 29, 2015

Let e start off by saying my primary heat is the woodstove. I have aforced air unit but choose to heat with wood. I have installed a woodstove insert into an existing fireplace. The chimney is an exterior masonry chimney.

I installed a stainless steel liner from the wood stove to the top of the chimney. Furthermore I insulated the flue with vermiculite and added the chimney cap. So no heat will escape up the chimney except what goes up inside the liner.

Now the smoke chamber of the existing fireplace gets extremely hot. And this is is the area I want to re-purpose. I want to bring that heat into the living space. So I have devised a plan to bring that air back into the living space. I have decided not to remove any of the bricks from the fireplace thus potentially waking the structure.

I will add some heat saver rings to the stainless steel liner located in the smoke chamber. This will radiate even more heat in the smoke chamber. I plan to add twould 6" inline duct work fans and force the air from the smoke chamber back into the living space.

That's the overall plan.

First though I have to prep to smoke chamber. I suspect that if i dont coat the walls theni will haveunwanted odors being pulled back in the room. I have already wire brushed and vacuumed the smokechamber.. Now I have to choose a product to coat the smoke chamber. The fire chamber is in decent shape. Their are a couple of ways I can do this. I can parge the smoke chamber with a product called ahrens chamber tech 2000. Or I can use high temp paint to seal in the odors. Just wondering if anyone has any thoughts on which product use.
I'm thinking high temp paint.

Excavator · Nov 29, 2015

Wood recycler said:
Let e start off by saying my primary heat is the woodstove. I have aforced air unit but choose to heat with wood. I have installed a woodstove insert into an existing fireplace. The chimney is an exterior masonry chimney.

I installed a stainless steel liner from the wood stove to the top of the chimney. Furthermore I insulated the flue with vermiculite and added the chimney cap. So no heat will escape up the chimney except what goes up inside the liner.

Now the smoke chamber of the existing fireplace gets extremely hot. And this is is the area I want to re-purpose. I want to bring that heat into the living space. So I have devised a plan to bring that air back into the living space. I have decided not to remove any of the bricks from the fireplace thus potentially waking the structure.

I will add some heat saver rings to the stainless steel liner located in the smoke chamber. This will radiate even more heat in the smoke chamber. I plan to add twould 6" inline duct work fans and force the air from the smoke chamber back into the living space.

That's the overall plan.

First though I have to prep to smoke chamber. I suspect that if i dont coat the walls theni will haveunwanted odors being pulled back in the room. I have already wire brushed and vacuumed the smokechamber.. Now I have to choose a product to coat the smoke chamber. The fire chamber is in decent shape. Their are a couple of ways I can do this. I can parge the smoke chamber with a product called ahrens chamber tech 2000. Or I can use high temp paint to seal in the odors. Just wondering if anyone has any thoughts on which product use.
I'm thinking high temp paint.

Why not just use or build a block off plate at the old damper frame area. That is what I did.

Wood recycler · Nov 29, 2015

Hi excavator, thanks for the reply. I do (or did until recently) have a plate like you have got installed now. And it works great. However, their is so much heat build up above the damper plate and bottom of the flue.

Is your chimney flue insulated? Not so much with the "chimney insulation wrap" but the vermiculite.

Excavator · Nov 29, 2015

Wood recycler said:
Hi excavator, thanks for the reply. I do (or did until recently) have a plate like you have got installed now. And it works great. However, their is so much heat build up above the damper plate and bottom of the flue.

Is your chimney flue insulated? Not so much with the "chimney insulation wrap" but the vermiculite.

mine is with the chimney insulation wrap. I have fire board 3/8 thick that i made block off plate from that i bought at lowes few years back

Wood recycler · Nov 29, 2015

Did you insulate the fireplace itself? I did. When I purchased the stainless steel liner I also purchased the insulation wrap. And that was all I was going to use. But the liner would not fit the chimney with the insulation wrap. So I removes the wrap and installed the liner. Then I discovered vermiculite and insulated the flue with it. I re-purposed the stainless steel liner wrap using it in the fireplace and directly above the fireplace. I uses sheet metal and glued the insulation to it.

It was functional but an eye soar with the surround removed.

Oh and I failed to mention....the wood stove insert I have has a terrible reputation for the blower motors going bad. I have gone through three of them. I don't like the loud noise and the little amount of heat it puts back in the room. It's takes a very long time to heat up the house useing that blower.

So that is why to complete makeover with the woodstove insert.

mellow · Nov 30, 2015

You have been working on this project for over 2 years now, you never do say what insert you burn in, if this is an older non-epa insert could it be all your heat is going up the liner and not out to the living space as a newer secondary reburn insert would do?

I do not see the temps that you do above my smoke shelf, so I am not looking to reclaim heat above the block off plate.

Wood recycler · Nov 30, 2015

Hi Mellow, I suppose your correct by saying this is a work in progress. The year I posted the flue Temps was the year I burned 2 year old split applewood.

I have thevogelzang colonial tr004. And have not been pleased with the blower motors. Their noisey and don't move enough air. So that's why I have a work in progress.

bholler · Nov 30, 2015

What do you mean by heat saver rings? I personally would stuff the smoke chamber full of roxul or ceramic wool. You want to keep the heat in the pipe taking to much heat off will cause problems for you

Wood recycler · Nov 30, 2015

This is what I mean by heat saver rings.

http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=1SPV4HW75DXRQC3MZS02

I am considering insulating the walls of the smoke chamber. And adding the above link. Finally using a 6" inline duct fan and duct that heat right back into living space.

I'm checking into roxul. I want to find out what forms it comes in. Faced or not faced? Whether or not the particals it's made up of are harmful for long time exposure.

I'm also looking into fiber board as a potential insulator.

Wood recycler · Nov 30, 2015

Here is another link for the heat savers. http://www.stovepipeheatsaver.com

bholler · Nov 30, 2015

Like i said i think pulling heat off of the flue is a bad idea and you are asking for trouble. I would just stuff the smoke chamber full and be done with it

mellow · Dec 1, 2015

Those rings are for singlewall black pipe that is attached to a free standing stove, I doubt they do much but will do even less attached to an insulated stainless steel liner.

Roxul has fiber particulates , it comes unfaced, not something I would recommend blowing air from, if you want to insulate that area for this experiment I would use concrete board.

jharkin · Dec 1, 2015

bholler said:
What do you mean by heat saver rings? I personally would stuff the smoke chamber full of roxul or ceramic wool. You want to keep the heat in the pipe taking to much heat off will cause problems for you

+1

What you are trying to do is conceptually similar to the Magic Heat device.... Known informally as the creosote creator around here. Bad idea.

Wood recycler · Dec 9, 2015

I have been exploring a variety of different types of fans/blowers. The blower that came my woodstove was poorly engineered. No matter how much Cleaning and maintenence they die a short noisey life. The blower didn't move but a little amount of air.

I am wanting to move more air. So I'm considering a squirrel cage blower that produces 800 cfm's.

I think the blowers that come with the woodstove blowers only produce between 50 and 100 cfm's. That isn't very much especially with a woodstove insert.

Any hvac members that know these things? Or members who have added extra fans to move air? I'd be glad to here from you.

begreen · Dec 9, 2015

800 cfm on a woodstove? That would be a hurricane in a living room and it would sound like one. 100 cfm rating is because the stove mfg. is trying to balance low noise with sufficient air movement.

bholler · Dec 9, 2015

And to much air will either not have enough time to get heated up or it will sap to much heat off. Fix the problems with the install and if that doesnt work get a better stove. You are making it way to complicated and i have a feeling you will end up making more problems for your self

Wood recycler · Dec 9, 2015

Thank you be green. And I am trying to avoid a hurricane with excessive noise. That is the reason I am considering a variable speed blower. I'm trying to strike a good medium.

branchburner · Dec 9, 2015

I'm going to again suggest blowing cool floor air into the space behind the insert, which will force the already-warmed air out and about. This works wonders with my free-standing stove that sits about halfway into my fireplace.

jharkin · Dec 10, 2015

bholler said:
And to much air will either not have enough time to get heated up or it will sap to much heat off.

Bingo. Knowing there is only so much heat output from the stove at a given burn setting (BTU/hr) , as you increase the airflow you are going to hit a point of diminishing returns where more airflow just decreases the exit temp of the air and does not increase heat transfer to the room. You may even cool down the stove to the point you kill off the secondary combustion and efficiency plummets. The companies that design the stoves have trained engineering staffs that know what they are doing, they all come up with similar CFM ratings for a reason....

If you want to do more than just guess at it, read up on convective heat transfer
http://www.engineeringtoolbox.com/convective-heat-transfer-d_430.html
https://en.wikipedia.org/wiki/Convective_heat_transfer
https://en.wikipedia.org/wiki/Heat_transfer_coefficient

Wood recycler · Dec 10, 2015

bholler said:
And to much air will either not have enough time to get heated up or it will sap to much heat off. Fix the problems with the install and if that doesnt work get a better stove. You are making it way to complicated and i have a feeling you will end up making more problems for your self

jharkin said:
Bingo. Knowing there is only so much heat output from the stove at a given burn setting (BTU/hr) , as you increase the airflow you are going to hit a point of diminishing returns where more airflow just decreases the exit temp of the air and does not increase heat transfer to the room. You may even cool down the stove to the point you kill off the secondary combustion and efficiency plummets. The companies that design the stoves have trained engineering staffs that know what they are doing, they all come up with similar CFM ratings for a reason....

If you want to do more than just guess at it, read up on convective heat transfer
http://www.engineeringtoolbox.com/convective-heat-transfer-d_430.html
https://en.wikipedia.org/wiki/Convective_heat_transfer
https://en.wikipedia.org/wiki/Heat_transfer_coefficient

Thank you for the links. I won't be doing any needless experimenting without first doing the homework. Thanks for bringing up the engineers. I'm going to reach out to Volgezang (who made stove).

rwhite · Dec 10, 2015

I as far as I can tell you are running a 8" liner on a 6 " stove is this correct?

For 2 years we haven't seen a pic of your setup.

The masonry is a heat sink, the stove is doing what it is designed to do. Heat objects, not air. Yes the brick will get hot.. It is not lost heat as it will be released back into the room slowly.

I seriously doubt your losing heat to the smoke chamber as if it was built right there should be a air gap between that and the exterior wall. Is the exterior wall hot to the touch?

The "heat band" may be the silliest gadget I have yet to see.

You need to post some pics so folks have an idea how they can help.

Smoked · Dec 11, 2015

Stove pipes are for venting, not heating. If you take too much heat off of the pipe, you may create a draft and or creosote problem. Like others have said, stoves are engineered to work a certain way. If you radically change the dynamics of the venting, you can expect other problems. Put in a nice insulated block-off plate and maybe even consider insulated cement board on the back and side walls of the old firebox to keep the heat off of those outside walls. I did insulated block-off plates this summer. It has been warm so far this winter so I have not run may basement install much at all but I can tell my living room install is putting off more heat or losing less! I am also considering doing the false side and back walls to keep from heating the bushes and ants outside. Hope that helps.

Wood recycler · Dec 11, 2015

The brick outside (exterior of the house) becomes warm after hours of burning. I have attached a pic of what I'm working with.

The first pic shows the woodstove outside the fireplace. You can see from the pic the fireplace box has been lined with insultation. I have since removed the insulation. I am searchin to replace it with some thing more astestic.

The other pic is the liner dangling in the smoke chamber. The pic doesn't show the insulated flue. Its hard to get that angle.

On the first pic located on both sides of the fireplace are the fans I use. The metal fan located on the left of the woodstove (only a tilly pictured) is a dual fan. That moves a lot of air back into the room. The fan iwas made by Marvin.

The black floor fan is a nice fan. It's relatively quiet too.

mellow · Dec 14, 2015

If you have the room make a roxul / concrete board sandwich in your firebox then paint it with black high temp paint.

https://www.hearth.com/talk/threads...lating-my-fireplace.75755/page-2#post-1635483

rwhite · Dec 14, 2015

Sorry for all the questions but I'm trying to get an idea of your set up to help out. You stated that the flue is insulated with vermiculite but the pic shows wrapped liner insulation. If the rest of the flue is vermiculite how is it held in or was it a poured slurry? If it were me I would reinstall the insert and use a BBQ thermometer probe and see actually how hot it is getting behind the surround, or how hot the brick is getting within 10" or so above the stove. I just have a feeling that what you are considering hot may not be. At 180 degrees you can only hold your hand on something for about a 3 count at most. That is not hot in stove terms and I would consider it completely normal and why we have clearance requirements.

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