Should I insulate the fireplace walls and rear?

[RickBlaine]

How much heat is "lost" by being absorbed by the brick? My sexy Englander 13 stove sits in a masonry fireplace, and I use an IR gun to record temps of 225 degrees F on the surface of the fireplace's black inside brick, while recording temps of 580 on the flue collar.

The bricks remain warm even after the stove cools down. I have a pedestal fan which blows into the fireplace and removes some of that heat.

I have a block-off plate, Roxul insulation above that plate, 15 feet of insulated liner running through my masonry chimney, a Roxul-insulated smoke shelf, and Roxul below the top plate. Outside with the IR gun, I measure no difference between air temperature and chimney brick temps. So, no heat loss.

Just wondering if I should add a layer of Roxul against the fireplace sides and back and then "seal" it with 3 metal sheets from Home Depot. Would that prevent the fireplace bricks from absorbing heat, and thus, allow more heat to radiate out immediately? Again, I don't detect a single degree of difference in the outside chimney walls vs. the outside air temp. I am not losing heat through the outside chimney. When it snows, the entire chimney stays dusted with snow even as a fire rages.

Not complaining....just wondering about increasing efficiency. All thoughts welcome!

 

[Grisu]

You may get heat quicker but you will loose the heat retention of the bricks. Nevertheless, I don't see how it could hurt but when you don't notice any heat loss on the outside it may be just a waste of your time.

 

[RickBlaine]

Thanks Grisu- that makes sense. No need messing with it then.

 

[mellow]

I wouldn't mess with it if you are recording no heat difference on the outside bricks. The main reason to insulate the fireplace is with an insert, the surround traps the heat in the fireplace, you have a fan blowing that heat out.

 

[RickBlaine]

@mellow: Thanks for your reply. I came across your original "insulation" thread when I was still lurking here- before I signed up. It got me thinking....

So I followed your nice write-up and checked the chimney temps several times over several days over different stages of the fires. No temp difference. So I guess the inside fireplace brick walls soak up some heat, but that heat is later released inside the house- not outside.