Would adding this to my exposed chimney pipe improve my stoves efficiency?

[rashomon]

My chimney is exposed (no chase). Looking at my invoice I believe it's a DuraVent 6DT (double walled) exterior Class A chimney.

It's warm to the touch when my stove is going. I use a FlueGuard thermometer probe to make sure I'm keeping my stove's exit gas temps within the ideal range.

Without a chase on a windy and cold day I imagine a lot of heat is pulled away from the chimney. I find myself needing to keep my air intake high to keep my exit gases in the good zone.

If I enclose my chimney in an additional pipe, like this, would that help? The diameter of this is only 0.8" larger than my chimney. I was thinking about wrapping some thin insulation around the chimney to act as a spacer (maybe something intended for hot water pipes?). Or maybe 3 dowels made of high temperature material running vertically -- this is just to provide even spacing and make sure one wall isn't touching the chimney. What do you think?

I guess if I'm worried about it being airtight I can just leave the top open, otherwise I could make small - 1/4" - cuts in the top and bend it inwards.

 

[stoveliker]

your Class A is already insulated.
Don't bother with the additional pipe; it's meant to run as it is. They use them in Canada too...

 

[Wisco Shepherd]

What temperatures are you seeing for flue temp? How long of a run and do you have a pipe damper?

Just to be thorough what is the moisture content on a fresh split for your wood?

 

[rashomon]

your Class A is already insulated.
Don't bother with the additional pipe; it's meant to run as it is. They use them in Canada too...

Thanks, I did realize it's double walled, but with how cold and windy we get I thought having a wind break could help it better maintain flue temps.

What temperatures are you seeing for flue temp? How long of a run and do you have a pipe damper?

Just to be thorough what is the moisture content on a fresh split for your wood?

I use the FlueGuard and I'm within optimal temps at all times, but I like to get as much heat from the stove as possible. My blower fan significantly lowers the exit gas temps so I need to compensate by leaving the damper open. I burn pipe (I know) and sometimes it's not fully dry (I'm aware).

My chimney is 10' on the exterior in an area that often gets very windy. The wind would constantly be pulling heat away from my double walled chimney which is warm to the touch.

I may just give it a test - only $25. I'm essentially just creating a wind shield to keep the chimney hotter. Maybe it would allow the blower to be used without loosing so much exit gas temps

 

[stoveliker]

Surely it won't make things worse. Though if you do something like that, do read the documents for your (brand) class A - don't want to violate the installation instructions of that pipe.

Your flue is relatively short, so robbing heat (which increases with flue height due to longer gas residence time in the flue) will not be large.

You mentioned dowels. Tackwelding nuts to the outer pipe (thin wall though...) and using bolts screwed in as stand offs might work better? That'd be tunable.

 

[Highbeam]

Be warned that class A chimney has a 2" clearance to combustibles requirement.

Unless you are using a "magic heat" device in your flue, I doubt that the blower is robbing much heat from the exhaust. If you blow air onto a fluegard thermometer it will artificially lower the meter reading because you are cooling the exposed bimettalic coil that is meant to be in still air.

An insulated chase can't hurt but I doubt it is much help in Denver on a 10' stack.

Oh and I'm burning 100% pine right now. It burns great and makes great heat in my cat stove. It is dry though.

 

[rashomon]

Be warned that class A chimney has a 2" clearance to combustibles requirement.

Unless you are using a "magic heat" device in your flue, I doubt that the blower is robbing much heat from the exhaust. If you blow air onto a fluegard thermometer it will artificially lower the meter reading because you are cooling the exposed bimettalic coil that is meant to be in still air.

An insulated chase can't hurt but I doubt it is much help in Denver on a 10' stack.

Oh and I'm burning 100% pine right now. It burns great and makes great heat in my cat stove. It is dry though.

Actually I do remember the 2" clearance thing. Probably not a good idea to enclose it that tightly. I could use a 14" HVAC pipe, but if I'm only curious, I may just go down to a 8" (which is cheap) and bend it open to act as a wind break. This is the kind of crap I waste my time on!

 

[stoveliker]

Again, I would not bother. It's meant and tested for the purpose you use it for. Folks in much colder climates use it too.

If you enclose it, you may have to leave the top and bottom open (I don't actually know requirements for encasing class A).
If you have to keep things open, that'll create convection flow in that space between the pipes. That air flow will cool things, so the benefit may not at all be significant.
If it does need venting, this suggests you do have some heat loss, but it won't be helped much by the pipe given the convection. And if it does not require venting of, then the losses are low anyway, meaning encasing it doesn't do much...

 

[Wisco Shepherd]

I use the FlueGuard and I'm within optimal temps at all times.

What is the temperature reading in degrees? Optimal can depend on lots of opinons.

I burn pipe (I know) and sometimes it's not fully dry (I'm aware).

Pine is fine but addressing your wood moisture content will do more from your problem than messing with a DIY triple wall contraption.

 

[Highbeam]

What is the temperature reading in degrees? Optimal can depend on lots of opinons.

Pine is fine but addressing your wood moisture content will do more from your problem than messing with a DIY triple wall contraption.