[Greenbuilding] Outsulating chimneys -- was Re: Fireplace options

[Bob Waldrop]

I am curious about the recommendation to "outsulate" an exterior 
chimney.  We have a woodburning stove that uses a brick chimney which 
was relined with a stainless steel liner at the same time we installed 
the wood-burning stove.  The chimney is brick, floor through the attic 
through the roof.  In the kitchen it is covered with plaster.  The 
chimney in the attic and that extends through the roof is not plastered.

Does "outsulate" mean you think we should put some kind of insulating 
material over the brick? I'm guessing not the chimney that's within the 
conditioned space, but the chimney that is in the attic and in the air 
above the roof?  What kind of insulation materials would you recommend 
for this?  I had not thought of the chimney as a thermal bridge.

Bob Waldrop
Oklahoma City


On 10/5/2012 12:35 PM, RT wrote:
> On Thu, 04 Oct 2012 19:27:21 -0400, Erin Rasmussen <erin at trmiles.com> 
> wrote:
>
>> EPA certified inserts or wood stoves is a minimum requirement in some 
>> areas.
>
>>
>> -----Original Message-----
>> From: Kirsten Flynn
>
>> We would like to reuse the existing masonry, demolishing and
>> rebuilding would be way out of this client's budget.
>
>
> I'd venture that the words "fireplace" and "Greenbuilding" probably 
> shouldn't used in the same sentence unless there's a "not" in there 
> somewhere.
>
> I'd venture that the best option would be to completely air-seal and 
> outsulate all of the masonry associated with the existing 
> fireplace/chimney so that it becomes beneficial thermal mass instead 
> of a massive thermal bridge and then use the fireplace as a masonry 
> surround for an EPA-approved (as a minimum) woodstove + insulated 
> steel chimney liner, one with a glass door to enable viewing of the 
> fire without sending all of the conditioned interior air up the chimney.
>
> As for fuel options for the urban Californian house, perhaps the 
> firelogs that are made out of compressed, reclaimed waste hardwood 
> sawdust might be pretty sensible.
>
> The "logs" that are made/sold locally (Ottawa Ontario/Gatineau Quebec) 
> are hexagonal in cross-section (so that they stack neatly) about 60 mm 
> (2.5 inches) in diameter and 275 mm (10.5") long with a 22mm dia void 
> running through the core and weigh about 1 kilogram each (ie very 
> dense) and considerably easier to handle/store than "real" logs.
>
> (I've heated exclusively with wood every since Second Year university 
> days (I did install a furnace in my home when I built it back in '85 
> but it has only been turned on once, to test it after 
> installation/air-balancing) so I have no experience with pellet stoves 
> but I can't imagine myself ever wanting one.)
>
> Since heat output of a volume of firewood is directly proportional to 
> density, as expected the little "eco" logs do burn very hot and of 
> course, since they are so dry, burn very cleanly.
>
> (I know these things about the "eco" logs because the manufacturer 
> gave me a sample pile to play with years ago. I had a Siberian Husky 
> pup who seemed to like gnawing on the "eco" logs, just like she would 
> on a real stick.)
>