Block off plate questions

[Blueox4]

I just installed a Osburn 2400 insert and the experienced installer who helped me and who has done dozens of stove and insert installations with lots of happy customers, when asked about the need for a block off plate he said one was not needed. He cut out the damper and put roxul in that area blocking it off with the roxul. Also, he insulated the exposed part of the chimney from the roof up to the end of the flue tile putting the insulation between the flue tile and the stainless liner then putting a raincap screwed on top of the flue tile with epoxy around the fluetile also. Is a block off plate really needed in this case? I can’t see how heat retention or any other factor would be impacted with how it’s currently installed but I also am new to wood burning somewhat and don’t know. Thank you!

I live in Upstate NY and it does get cold here.

Here’s a thread with some pics of the insert going in. If I need a block off plate I’d rather put one in now before the insert is used for the first time in the coming months.

https://hearth.com/talk/threads/a-couple-pics-of-my-osburn-2400i-install.169154/

 

[webby3650]

The installer is correct, you don’t “need” one. But, it will increase performance. His other customers are happy and satisfied with their installs because they don’t know the difference. I’d bet if they installed a block off plate now, after running it a while they’d say otherwise.

 

[kennyp2339]

The idea of the metal block off plate is to keep the radiant heat the insert produces from going up the chimney. Many people that install a block off plate install it lower than the existing damper, usually a hair above the lintel, most almost always put roxal insulation above the metal plate, then screw all 4 sides of the metal plate lip using tap cons and hit the groove with high temp silicone.
Some members have even taken the extra step (with good results) of insulating the brick sides of the fireplace, this keeps the heat from being absorbed into the backside of the brick chimney; a member had a thermal imaging camera and did a nice thread showing before and after pics of his insulation job, he also noted that the insert ran warmer, he could close the air damper down even more than previous thus having a increased burn time, and a warmer house when the blower was on.
I would say if you live in a colder climate (like upstate NY) you should really look into this.

 

[Bushels20]

Blueox4,

I too was in your position about 6 months ago. I was wondering whether or not to Install the block plate. While I’ve not yet ran the stove with it installed, it was an easy DIY project. I would say go for it, it can’t hurt and most certainly is going to improve stove efficiency and heating capability by retaining heat.

Props to “begreen” for sharing this with me initially when I asked this same question.

https://www.hearth.com/talk/threads/another-block-off-plate-install-with-pics.71281/

 

[begreen]

An insulated block off plate is most beneficial with an exterior wall fireplace. With some interior installation where the masonry can release heat back into the house envelope it is not needed. If exterior wall, then putting some insulation on the face behind the insert can also help a bit.

Here is another resource page. The links at the end of the article show several examples of installations.
https://www.hearth.com/talk/wiki/why-damper-seal-is-needed-block-off-plate-install/

 

[Blueox4]

My insert is installed in a interior masonry chimney that goes through the center of my home. I have not decided whether I will pull the insert out to put in a block off plate or not. With my particular situation, looking to only heat around half my house, the living room and family room half a floor up, I think I’ll be OK. I may see how it goes this heating season and decide after that.

 

[begreen]

I'd try it for a season as it is without the block-off plate then. It might be fine.

 

[Bushels20]

I ageee. With the interior chimney and your (relatively) limited heating wishes, the block plate may not be needed.

There are install options for the block plate to avoid an insert removal, but, if you’re going to do it and make the commitment to heat with an insert/stove, if even it’s part time or half the home; I suggest a full removal and seamless block plate. But, don’t let stove/insert removal stop you from the project: it can be don’t without removing the unit.