Blockoff plate or seal/insulate fireplace front??

[Cedrusdeodara]

Hello all,

I had my first insert installed this fall and after only two months of operation, I am swapping it out for a larger unit (I should have come to hearth.com first before selecting an insert based on the manufacturers size suggestion). Anyway, I paid for the initial install, but to save some $$ I plan on doing the swap out myself. The installer installed a double walled 6" sleeve and chimney cap/screen that insulated the top of the sleeve from the existing flu, but he did nothing in the firebox to prevent the removal of heat/air from the house. Per my new inserts manufacturers instructions for the Napoleon 1402, they suggest:

"Means must be provided to prevent room air passage to the
chimney cavity of the fireplace. This may be accomplished by
sealing the damper area around the chimney liner, or sealing
the fireplace front"

They describe how to cut a flanged blockoff plate out of sheet metal. I was curious how one would go about doing the other option for sealing the fireplace front. Could this be a simpler alternative for me to do? Does it simply mean running a strip of silicone insulation where the surround meets the firebox and where the surround meets the insert? Any and all help would be greatly appreciated.

I believe that part of the problem with my existing unit is that room air is being drawn by the unit. I've noticed turbulent airflow (soot blowing) in the small areas near the base of the surround above the hearth.

One other quick question, any additional installation equipment that I should ask for when picking up the stove beyond the actual stove, surround, door, firebrick, etc.?

Thanks,
Cedrus deodara

 

[Cedrusdeodara]

No 911? I tried a search but couldn't find any threads dealing with insulating the face of the fireplace/surround to negate the need for a blockoff plate.

 

[Hogwildz]

Most insert come with the surround. I myself have the surround and installed a lower block off plate just below the original fireplace damper.
The top should have a top plate that the liner passes through and seals off the top.

 

[Cedrusdeodara]

Hi, My insert does come with a surround, but the decision I'm trying to determine is whether to install a blockoff plate or insulate where the surround meets the firebox/fireplace face and insert (to negate the need for a blockoff plate?? maybe??). I do have it sealed off at teh top of the chimney between the 6" ss insert and the flu, but no containment below as of yet.

Thanks

 

[bren582]

I would go with the damper block off plate especially if your chimney is outside the envelope of the house. Squeeze every BTU of efficiency out of the install by preventing heat from from escaping up the flue.

It's often difficult to seal the front surround. In my case due to a brick face plus some of the heat from the cavity or firebox escapes from around the surround back into the room due to the fact that it's blocked from going up the flue by the damper block plate,,

 

[stovetechri]

in my state you have to have a block off plate if you do a starter liner or if the stove is installed with no panels. a block off is not required if its a full liner with a top plate and panels. ive never seen anybody try to seal the panels to the wall but im sure you service/chimney guy wouldnt like it

 

[international5288]

When I did my insert install w/full liner I was told I did not have to do a damper blockoff. (exterior brick chimney) Well, after 2 months of burning I decided to do a blockoff, because in the AM a lot of my room heat was going into the chimney. My blockoff is lower than the damper, from the lintel straight back horizontally to the back of the heatform. (about 4" above the stove) It is thin steel plate with several layers of ceramic insulation on top. Just installed it today and tonight is my first burn with it. It has made a very noticeable difference in the heat output of the stove. If I were you that's the route I would go, as not only does it seal in room heat, but it also captures heat from the back of the stove and makes it go into the room.