What is the benefit of a block off plate? Insert, exterior chimney

[Jedi]

I have a question too. All my reading on these plates always are with exterior chimneys. Are there any benefits for interior chimneys? Has anyone noticed a difference in heat/performance after installing a damper plate in an interior chimney?

 

[weatherguy]

I have an interior chimney but when I put a block off plate at the bottom I had a significant heat rise, don't remember the numbers as it was a few years ago but it was noticeable.

 

[Poindexter]

Checking in as a dis-interested observer. I have been a member here for, I dunno, 6-8 years.

I own a freestander. I didn't know what "block off plate" was when I joined here.

In all of my time here, the number of folks who have come back and said "I put in a block off plate like you guys told me to do, and it was a waste of money." Is zero.

In all of my time here, the number of folks who come back and say "Wow, my stove is putting way more heat into my house since I put in the block off plate." Is 100%.

I am happy for you that you are satisfied with the current performance of your insert. You are welcome to cut and split and stack and burn all the cordwood you want, makes no nevermind to me. If you come back here in a few weeks and post up that your new block off plate was a waste of money, you will be the first one I heard of around here, ever.

Good luck and best wishes.

 

[KDubU]

Please use Roxul as insulation, not the one pictured in your first post. This is very important.

 

[weee123]

Please use Roxul as insulation, not the one pictured in your first post. This is very important.

And to expand on this, it’s because Roxul is fire rated and that faced fiberglass will smolder and burn under heat.

 

[bholler]

I have a question too. All my reading on these plates always are with exterior chimneys. Are there any benefits for interior chimneys? Has anyone noticed a difference in heat/performance after installing a damper plate in an interior chimney?

I put one in just about every insert install.

 

[Jedi]

Thanks for the replies everyone. Will be in my to-do list. My insert doesn't get installed until Jan or Feb, but being an interior chimney the dealer/installer said it wasn't necessary. Since they need to cut off the damer for install, I should wait until after to do this. Or maybe I can do a template now with cardboard, and make it as instructeed in the "instructions" sticky thread and have them install it for me?

 

[Mijoka]

Well that space will be heated up by the liner anyways. Since its blocked off up top and bottom, there no cold air intrusion and it will just keep that space warm

Is there a concern about moisture being trapped in that space during the non-heating months? Generally speaking, trapped moisture is not a desirable thing with masonry, especially on older houses with soft brick.

 

[CONick]

Checking in as a dis-interested observer. I have been a member here for, I dunno, 6-8 years.

I own a freestander. I didn't know what "block off plate" was when I joined here.

In all of my time here, the number of folks who have come back and said "I put in a block off plate like you guys told me to do, and it was a waste of money." Is zero.

In all of my time here, the number of folks who come back and say "Wow, my stove is putting way more heat into my house since I put in the block off plate." Is 100%.

I am happy for you that you are satisfied with the current performance of your insert. You are welcome to cut and split and stack and burn all the cordwood you want, makes no nevermind to me. If you come back here in a few weeks and post up that your new block off plate was a waste of money, you will be the first one I heard of around here, ever.

Good luck and best wishes.

This is excellent information. Thank you for sharing. This really helped drive it home. “It’s worth it”.

I’m happy that I’ll have a couple months of burning under my belt before I install the block off, so that I can compare before and after. I’ve spent a surprising amount of time in front of this insert. Turns out I’m an addict 😄

 

[CONick]

Please use Roxul as insulation, not the one pictured in your first post. This is very important.

Thanks for the follow up! I will definitely NOT use the Kraft-faced fiberglass insulation I showed in the photo.

I actually have a phone call in to my installer (left a voicemail for a callback). I’m not going to be rude or accusational or anything, but I genuinely want to know what he says. I’m gonna say “hey, so I noticed this insulation you left for me has vapor barrier paper on it. Is this safe to use?”. I’m just curious what he says. Will let you all know.

 

[CONick]

Is there a concern about moisture being trapped in that space during the non-heating months? Generally speaking, trapped moisture is not a desirable thing with masonry, especially on older houses with soft brick.

For me personally, it’s not a concern. But that’s because I live in Colorado which is a high altitude desert. We don’t have moisture related problems like most do.

But my assumption would be that if you have a good seal up top (properly sealed top block off plate), that you’d be ok. Mine is sealed very well at the top.

 

[begreen]

Thanks for the follow up! I will definitely NOT use the Kraft-faced fiberglass insulation I showed in the photo.

I actually have a phone call in to my installer (left a voicemail for a callback). I’m not going to be rude or accusational or anything, but I genuinely want to know what he says. I’m gonna say “hey, so I noticed this insulation you left for me has vapor barrier paper on it. Is this safe to use?”. I’m just curious what he says. Will let you all know.

Even if it didn't have the vapor barrier, fiberglass insulation is not appropriate for contact with the liner. It has a lower melting point than a mineral or ceramic wool like Roxul or Kaowool.

 

[CONick]

Will do! Thank you. Roxul or Kaowool 👍

 

[mellow]

Next you will want to insulate that fireplace, it has been proven to help keep the heat in the insert and blown out via the fans, not out to the masonry and warm the outside.

See my signature to learn more.

 

[CONick]

Next you will want to insulate that fireplace, it has been proven to help keep the heat in the insert and blown out via the fans, not out to the masonry and warm the outside.

See my signature to learn more.

yeah! I was thinking that I might as well do that while I'm in there. My fireplace has what looks like cement board already in place, or possible it's part of a cement form? I think it's original (1973) because it is flush with the sides/top of firebox like it was supposed to be there.
But I've got 6'+ all the way around my insert, so thank you for the tip on insulating. I read your whole thread.

Do you ever see people putting rigid Roxul sheets on the back/sides of firebox, then using tapcons with large washers? The durock is nice, my box will be closed off with a face plate around the stove, so it doesn't need to look nice. Just one less step if I didn't need the Durock.

This is what's in the back/sides of my firebox now:

 

[mellow]

I have never been able to source the rigid roxul sheets so I use Micore or concrete board. Will the tapcons have something to bite into? I used them in my metal firebox. And you are correct once the shroud goes up it is all hidden.