Question about 2 things i've seen on youtube

As a test I put once an old phonebook with the wood in the stove. It kind of burned/incinerated but I was surprised for how long it still was visible in its original shape. I found later a few pieces in the ash suggesting that even in a hot stove with plenty of wood surrounding it, it does not burn well. I feel that those paperbricks will not fare any better. I certainly would not fill up my stove with them and expect a good burn.

For the heat reclaimer: Yes, it may add some heat but you will get problems with draft and plenty of creosote accumulation. Don't be surprised to have a chimney fire soon after installing one. The stove is there to heat, the pipe is there to keep the draft going and to vent the flue gases outside.

Fins on an air-cooled dirt bike motor help to dissipate heat. These don't look as good but they may help slightly buy probably not enough to justify the cost.

Skip the shortcuts, nuttin but trouble

Kingdoc said:

the heat reclaimers in the video do not go in the pipe. That's why I was wondering about them.

Click to expand...

If they did not reduce the temperature inside the pipe they would not put any heat into the room. If they put heat into the room the lower flue temperature will lead to possible draft and/or creosote problems as Grisu already pointed out.

Overall I think they are a bad idea but let me play devil's advocate for a moment.....

Flue gasses in burn tube style stoves seem to be plenty high to the point of being wasteful. I think I could skip ever sweeping my chimney in the Enerzone....it is always incredibly clean. Vice versa the Blaze King builds plenty of creosote to the point that I should be sweeping mid season. Somewhere in the middle sounds fine to me. A flue whose run is open to the room 20 feet up will lose a decent chunk to the air. If a good fin system could be created to acheive the same for a chase setting where the run may only go up five or six feet in the interior of the house but then runs inside a chase for the rest of the way up sounds like a decent plan. For an exterior chimney you generally want the extra heat in the chimney to prevent creosote problems or loss of draw.

I would save your money. Put it toward purchase of additional firewood.
And/or don't waste your time reading about these gadgets......put this time towards processing more firewood, that way you will certainly get more heat!!

My 2 cents.

BrotherBart said:

Click to expand...

Priceless

Did that lab lose its foot during testing ?

I have measured the surface temp vs. the interior gas temp on my wood stove and coal stove and it runs a bit less than 1/2 on the surface for both. In my opinion it is due the boundary layer between the flue gases and pipe surface. If you want to get more heat you need to get the heat in the center to the surface and is commonly done with a turbulator, a spiral shaped piece of metal like a giant corkscrew that forces the gases in the center to the surface of the pipe. These are used every day in tube boilers to get more heat out of them. It should barely if at all reduce the draft and might make less creosote as that forms on the surface of the pipe rather than the center gases just passing through more than hot enough already by a factor of 2. best part no moving parts no electricity needed either,but would have to be removed for chimney cleaning.

Last I knew it was stove builders rules for no shields less any NFPA reductions for heat shields so might be as close as 12 inches or slightly less.

begreen said:

These are not shields at all, they are radiating collars. Proper stove pipe shields reduce the clearance down to 6".

Click to expand...

the nfpa 66% reduction on wall behind the connector will allow you down to 6 inches. the ul listed stove pipe shields which mount to the pipe allow only 50% reduction down to 9 inches. im 11 inches from combustables and have both for piece of mind lol.

I don't believe these will have any signifigant change in horizontal output as each of the protrusions is essentially an airgap with a radiant barrier. heat would get trapped in that space and forced to move vertically. which would in theory actually decrease clearance (although not very much) as well as the flat spots that actually contact the pipe don't add any substantial amount of surface area to the pipe.

begreen said:

Hmm, looks like some say it reduces clearance 50% and others say to 6", but I think you are correct at least for ceiling clearance.

"Using a "Heat Shield" on a single wall stovepipe allows you to reduce the clearances from 18" to 6" to the wall and 9" to the ceiling."
http://www.rockfordchimneysupply.com/articles.php?article=Clearances_to_Combustible_Materials
http://www.efireplacestore.com/cpf-54120.html

Click to expand...

my bad I was going by the brand I have which is an adjustable length. if I remember correctly I bought this brand because the ad specified it was ul listed. and some of the others I looked at made no mention as to a ul listing. which seemed to me like if they had the listing they would have advertised it. but I cannot say 100% they were not cause I didn't buy the other brands I looked at to read their literature to verify if they were or not.

if you read the last question (number 6 click to see them all) in the homesaver brand it says no documentation could be found and that it meets nfpa 9.5.1.2. on page 32, as in it is a 24 guage heat shield with 1 inch airgap. however if you go up to 9.5.1.1 diagram it shows how wide your protection must be. but doesn't describe at all what the reduction would be if placed partially around the pipe and not flat on wall. or how far around the pipe it must go ect. so I don't know if that is their interpretation of the code or what. but ul listed has actually been tested.

http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=211

I believe my decision was also made after seeing a post about most heat shields not being ul listed.

I read the NFPA rules to say I could go down the 66% of the listed clearance and in my mind roughly from 18 inches to 12 and what I settled on and the heat shield I built is not even warm to the touch. My heat shield is brushed aluminum on 2X3 metal studs and does provide a good amount of radiant heat reflected back into the room and plenty of air gap. My thought being the screws that connect to the supports and heat shield do not go into the wood so should be very safe and has worked for years and never gotten more than slightly warm. My problem with the wrap around tabs is that they can not transfer any more heat than the surface area attached to the pipe so not much better than 6 inches of 6 inch pipe and if worked the next one in line will put out less heat than the one before it. This does not solve the problem of much higher gas temp than the surface temp due to boundary layer issues. They would probably do more good on the inside of the pipe than the outside as at least cause some turbulence and break the boundary layer and reach into the area much hotter to gather heat. Even doing all that some heat sink compound is probably needed to connect the parts thermally. At the end of the day close to useless. I know the heat reclaimer gizmo with the fan not loved but at least it takes heat from the center gases and uses a fan to send them out but needs a fan so a loser in my mind. I don't want to rely on outside energy needed.