Block off plates, seriously. Is this a $$ making scam?

The block off plate is usually something an installer will try to get out of installing. Because it is a pain in the ass to install.
Most here install themselves a $7.00 pc of 26 gauge galv. at the local box store, some fasteners and a tube of high temp silicone, and a pc of rope gasket for around the liner where it goes through the plate.
Not much cash to scam for.
The first thing usually heard complaints of when folks do not have one..........
I'm not getting the heat I think I should be getting..........
I get a cold air drat from around the insert, especially when its not in use.
Dampness &/or creosote smell.
Not always all of the above, but at least one, and usually the first one.
The plate keeps heat from going up, getting absorbed by the masonry, and the masonry releasing it to the great outdoors.
Can ya use fiberglass, sure, but I would not use it on mine. It does NOT block air flow. It is rated for 600 degrees. if you have a chimney fire, it will be useless.
And quite honestly, I have seen at least one installer here comment that it is fine to use fiberglass. I can say, he would never be installing anything in my home.
Just my feelings, and my right to them.

The only reason an installer wants to use fiberglass or another insulation matt is because they are either unskilled enough with sheet metal to make a decent block off plate, which is really not hard to do. Or they are just plain lazy, and don't want to take the time.

I understand where you are coming from on this, I used kaowool and did a soft block off plate for my insert. Works great on keeping the heat where I want it.

boostnut said:

OK, lets be honest here. Is there really an advantage to a fabricated steel block off plate when compared to just stuffing the damper area with insulation? Yeah, I’ve got a block off plate I made up with 16 gauge steel the day I installed my insert. Mine has never run without the plate so I have no idea if its doing anything for me. Most installers in this area (hacks from what I’ve seen) are just stuffing the damper area with insulation after putting the liner in place. Makes sense to me since it will stop more heat from going up the ol chimney than a lightweight steel plate. So, does code require a steel block off plate in some areas or is this just some sort of a profit making “up-sell” someone dreamed up years ago that has caught on?

Now the reason I ask. A good friend is getting ready to install a Lopi insert. Installer says that he would just use some insulation in place of the original damper. Lopi manual says to install a block off plate. He calls me to ask what I’ve done and why. Now I ask you, WHY did you spend the time or $$ to have a block off plate and what are the REAL advantages of having one?

Click to expand...

Your anger at this issue confuses me. You either need more or less coffee. I'm not sure at this point.

I have two stoves installed; One with a block off plate and one without a block off plate with only insulation used to seal off the chimney.

The stove without the block off plate:
-Had multiple leaks that created a lot of heat loss. Had to have the installer come back on two different occasions to add more insulation
- I have on-going concerns, that due to the initial leaks in insulation, future leaks may occur due to settling, humidity, age, what ever.
-I had to use high temp caulk around other areas to eliminate leaks that I felt wouldn't have been needed if a block off plate would have sealed off access to the chimney.

The stove with a block off plate:
-No leaks.
-No issues.
-No caulking.

For me, I feel the block off plate is the better way to go.

Both stoves were installed by the same installer. The installer is a reputable installer in the area that comes highly recommended by multiple individuals. Apart from the insulation issue with the second stove I would use him again and recommend him to other in my area. (though, I will be installing the third stove myself)

We use rockwool and it is fairly "stuffable" when doubled over. Not sure how much of an "upsell" the OP is so concerned about? Were you charged a painful amount of money for it, like over $100 or something?

BrowningBAR said:

boostnut said:

OK, lets be honest here. Is there really an advantage to a fabricated steel block off plate when compared to just stuffing the damper area with insulation? Yeah, I’ve got a block off plate I made up with 16 gauge steel the day I installed my insert. Mine has never run without the plate so I have no idea if its doing anything for me. Most installers in this area (hacks from what I’ve seen) are just stuffing the damper area with insulation after putting the liner in place. Makes sense to me since it will stop more heat from going up the ol chimney than a lightweight steel plate. So, does code require a steel block off plate in some areas or is this just some sort of a profit making “up-sell” someone dreamed up years ago that has caught on?

Now the reason I ask. A good friend is getting ready to install a Lopi insert. Installer says that he would just use some insulation in place of the original damper. Lopi manual says to install a block off plate. He calls me to ask what I’ve done and why. Now I ask you, WHY did you spend the time or $$ to have a block off plate and what are the REAL advantages of having one?

Click to expand...

Your anger at this issue confuses me. You either need more or less coffee. I'm not sure at this point.

I have two stoves installed; One with a block off plate and one without a block off plate with only insulation used to seal off the chimney.

The stove without the block off plate:
-Had multiple leaks that created a lot of heat loss. Had to have the installer come back on two different occasions to add more insulation
- I have on-going concerns, that due to the initial leaks in insulation, future leaks may occur due to settling, humidity, age, what ever.
-I had to use high temp caulk around other areas to eliminate leaks that I felt wouldn't have been needed if a block off plate would have sealed off access to the chimney.

The stove with a block off plate:
-No leaks.
-No issues.
-No caulking.

For me, I feel the block off plate is the better way to go.

Both stoves were installed by the same installer. The installer is a reputable installer in the area that comes highly recommended by multiple individuals. Apart from the insulation issue with the second stove I would use him again and recommend him to other in my area. (though, I will be installing the third stove myself)

Click to expand...

The question is, will you ever be able to buy that third stove? The gods have alligned themselves against you.

Franks said:

BrowningBAR said:

boostnut said:

OK, lets be honest here. Is there really an advantage to a fabricated steel block off plate when compared to just stuffing the damper area with insulation? Yeah, I’ve got a block off plate I made up with 16 gauge steel the day I installed my insert. Mine has never run without the plate so I have no idea if its doing anything for me. Most installers in this area (hacks from what I’ve seen) are just stuffing the damper area with insulation after putting the liner in place. Makes sense to me since it will stop more heat from going up the ol chimney than a lightweight steel plate. So, does code require a steel block off plate in some areas or is this just some sort of a profit making “up-sell” someone dreamed up years ago that has caught on?

Now the reason I ask. A good friend is getting ready to install a Lopi insert. Installer says that he would just use some insulation in place of the original damper. Lopi manual says to install a block off plate. He calls me to ask what I’ve done and why. Now I ask you, WHY did you spend the time or $$ to have a block off plate and what are the REAL advantages of having one?

Click to expand...

Your anger at this issue confuses me. You either need more or less coffee. I'm not sure at this point.

I have two stoves installed; One with a block off plate and one without a block off plate with only insulation used to seal off the chimney.

The stove without the block off plate:
-Had multiple leaks that created a lot of heat loss. Had to have the installer come back on two different occasions to add more insulation
-I have on-going concerns, that due to the initial leaks in insulation, future leaks may occur due to settling, humidity, age, what ever.
-I had to use high temp caulk around other areas to eliminate leaks that I felt wouldn't have been needed if a block off plate would have sealed off access to the chimney.

The stove with a block off plate:
-No leaks.
-No issues.
-No caulking.

For me, I feel the block off plate is the better way to go.

Both stoves were installed by the same installer. The installer is a reputable installer in the area that comes highly recommended by multiple individuals. Apart from the insulation issue with the second stove I would use him again and recommend him to other in my area. (though, I will be installing the third stove myself)

Click to expand...

The question is, will you ever be able to buy that third stove? The gods have aligned themselves against you.

Click to expand...

It sure as hell seems like it! If you see me posting a rant on Monday about getting screwed out of a third stove yet again, you can pretty much confirm that the gods are indeed against me.

[Now the reason I ask. A good friend is getting ready to install a Lopi insert. Installer says that he would just use some insulation in place of the original damper. Lopi manual says to install a block off plate. He calls me to ask what I’ve done and why. Now I ask you, WHY did you spend the time or $$ to have a block off plate and what are the REAL advantages of having one?[/quote]

Tell him to forget the blockoff plate if he's going to be a tightazz. Then when he starts complaining how crappy his stove works, you can say "I told you so" should of gottin that blockoff plate. Without it it's like leaving a window open all the time. those surrounds around inserts aren't air tight, not at all. It just makes sence.

boostnut said:

OK, lets be honest here. Is there really an advantage to a fabricated steel block off plate when compared to just stuffing the damper area with insulation? Yeah, I’ve got a block off plate I made up with 16 gauge steel the day I installed my insert. Mine has never run without the plate so I have no idea if its doing anything for me. Most installers in this area (hacks from what I’ve seen) are just stuffing the damper area with insulation after putting the liner in place. Makes sense to me since it will stop more heat from going up the ol chimney than a lightweight steel plate. So, does code require a steel block off plate in some areas or is this just some sort of a profit making “up-sell” someone dreamed up years ago that has caught on?

Now the reason I ask. A good friend is getting ready to install a Lopi insert. Installer says that he would just use some insulation in place of the original damper. Lopi manual says to install a block off plate. He calls me to ask what I’ve done and why. Now I ask you, WHY did you spend the time or $$ to have a block off plate and what are the REAL advantages of having one?

Click to expand...

Do you know what insert he is installing? Because my Lopi insert manual REQUIRES the block off plate for an install that only takes a pipe/liner up past the smoke shelf, and then it's in an unlined chimney. So the block off plate is to physically stop a chimney fire from entering your house. The manual does not require or even recommend or mention a block off plate on a liner install that goes all the way up the chimney. (I know it is recommended by folks here in terms of heat loss) but the manual does not rec. a plate at all. If your friend is not installing WITH a full liner though, he better have that block off plate. And I don't think that in that case, the reason that they require it, that insulation stuffed in there would suffice.

Now if he's doing a full liner and this plate is just something the installer recommends, it's probably for heat loss and I agree that the plate should have some kaowool or something backing it to provide better insulation properties since it's for heat loss.

boostnut said:

OK, lets be honest here. ...snip...Most installers in this area (hacks from what I’ve seen) are just stuffing the damper area with insulation after putting the liner in place. Makes sense to me since it will stop more heat from going up the ol chimney than a lightweight steel plate. So, does code require a steel block off plate in some areas or is this just some sort of a profit making “up-sell” someone dreamed up years ago that has caught on?
...snip

Click to expand...

Not sure how you think the insulation is stopping more heat than the steel plate. The issue that a block off plate solves isn't BTU transfer, as there is lots of that up there to begin with, given the really long stainless heated tube up there.

The issue is air circulation and leakage. A chimney is not an airtight enclosure, and if a fresh supply of room air is available, then stack effect will take place inside the chimney - warm air will leak out cracks and crevices as it is allowed to be replaced by the air from the room, which is in turn warmed, cycle repeats.

It isn't about R value, it's about air sealing. You can achieve some air sealing by stuffing fibreous aterial around the liner, but air won't flow thru a steel plate at all.

As for code requiring a block off plate, well, sort of. Code requires that instructions be followed, and if instructions say a plate is needed, as you say they do in your friends case, then code requires it, cause code says to install according to manufacturers instructions.

Just referring to your "$$making scam" comment.

What I like is that a metal blockoff plate is it's aslo a fire-stop. Who would know how? but say that chimney or liner started to burn and maybe that fiberglass ins. got soaked with creosote and started to burn. just knowing that metal plate is there is a little extra safety insurance.

[/quote]

Do you know what insert he is installing? Because my Lopi insert manual REQUIRES the block off plate for an install that only takes a pipe/liner up past the smoke shelf, and then it's in an unlined chimney. So the block off plate is to physically stop a chimney fire from entering your house. The manual does not require or even recommend or mention a block off plate on a liner install that goes all the way up the chimney. (I know it is recommended by folks here in terms of heat loss) but the manual does not rec. a plate at all. If your friend is not installing WITH a full liner though, he better have that block off plate. And I don't think that in that case, the reason that they require it, that insulation stuffed in there would suffice.

Now if he's doing a full liner and this plate is just something the installer recommends, it's probably for heat loss and I agree that the plate should have some kaowool or something backing it to provide better insulation properties since it's for heat loss.[/quote]


Was thinking of something....say you have a full liner and capped at the top, but no block off plate.
Although you would have some heat loss up the chimney, you would also have a warmer chimney...which would help draft and perhaps yield less creosole?

boostnut said:

The insert is a Lopi Declaration....snip... Liner will not be insulated as this is a centrally located interior chimney.

Click to expand...

Even a central chimney may need insulation. The issue insulation isn't just good draft, but thermal protection of combustibles adjacent to the chimney structure, which there are lots of on an internal chimney. Unless he is sure he has 2 inches of air space between the external surfaces of the chimney and the rest of his house, both code and likely the instructions for the liner require insulation.

Always read the instructions. While your at it, give him a copy of the chimney liner best practices that you can download from the link in my signature block - might save him some hassle when he speaks to his installer.

ilikewood said:

snip...
Was thinking of something....say you have a full liner and capped at the top, but no block off plate.
Although you would have some heat loss up the chimney, you would also have a warmer chimney...which would help draft and perhaps yield less creosole?

Click to expand...

You won't have a warmer chimney, you'll have a colder chimney, cause the air around it will be constantly changing and cooling it down. If you want it warmer, then seal the 25 foot long 500-1000*F pipe into an enclosed space with the block off plate. The heat that radiates off the liner inside the chimney is way higher than any heat you think is going into the space from the room below.

CleanBurnin has "nailed" this with both of his posts. Long ago I did not understand that insulation does not stop airflow, it stops heat/cold transfer. A family member in the commercial insulation business helped me understand this elusive fact with a hair dryer demonstration. The blockoff plate stops air flow and the insulation maintains heat on the firebox side of the chimney. There are some ceramic fiber blankets with rigid surfaces that accomplish both - air containment and insulation. Without a blockoff there will never be a "dead-air space" that can reach an equilibrium and maintain itself, IMO.

CleanBurnin & Retreadsme
;-) perfect

IMHO, the block off plate is essential in retaining the heat created by any stove/insert. For obvious reasons: as its name states, it blocks off heat and/or fire. It is better to have some sort of mineral wool insulation such as Roxul or any mentioned in the other posts, above the steel plate. Also as mentioned, fiberglass insulation is by no means the correct material to use in this case. As a union carpenter, I've been insulating comercial jobs for nearly ten years now. When you want fire retarding you use mineral wool, fiberglass is only good for sound and R-value. It is a proven fact that ANY insulation alone will not stop vapors, such as heat. It will certainly help but will not do the job correctly. The steel block off plate will ensure no vapors will escape into the chimney as well as provide a fire retardant barrier. Fire caulking should be used to seal against the bricks. The point of an insert/stove is to heat! If he wants it to yeild the highest reward then tell him to do it.

Its funny, I had inquired on this topic about a year ago after my Lopi Answer Insert was installed....and the majority of posters here...long term ones at that indicated that I did not need a block off plate in my situation hh:

ilike - I'm not sure about your particular situation, but I'm inclined to say an insert/stove put into a fireplace located on or extending outward from an external wall will receive more benefit with a blockoff than a flue/chimney that is in the middle of a house. I've seen "reports" that indicate as little as 2% heat is gained by using a blockoff and I've seen "reports" that as much as 5% is gained. I question those number on both ends, but have no means to refute them scientifically. A 2% gain may not be significant enough for some to justify spending the extra $ for a blockoff and for them it may be the right decision. It's just a question of how close to max. efficiency one wants to get with their resources available, and be safe. I'm attempting to squeeze every btu out the front into living space as I can and if I could, I'd have zero btu's going up the stack, but that's not possible. I lined my entire fireplace with 1" thick, 8-lb density ceramic blanket before installing the insert to prevent heat-sink affect from the bricks with my exterior chimney as well as lining the top of the blockoff plate with the same ceramic blanket. Probably 95% new and old-time installers will say "that's not necessary"; and they'd be right, but I'll gain btu's in the living space....... (hopefully)!

BrotherBart said:

Dollar making scam for who? Everybody comes here saying they have to beat installer's over the heat with a poker to get them to install a block off plate. It is the stove owner's that want the damn things.

Personally I think the shroud on a insert is just like a block off plate. Just lay ceramic insulation on top of the thing.

Click to expand...

My insert shroud certainly seems to be. I can nearly put my hand on the top when the stovetop right near it is 500 degrees. (I don't have the surround panel on and have decided not to use it.) I can also touch the iron damper that is a foot above the stove and it's barely warm, while the fire in the box is raging for hours. So far, I don't really feel like I am losing much heat up the chimney. May still make a block off plate up, but I don't feel like it's imperitive in my case.

The block off plate in my fireplace was free!

I was on a job framing the Fire/police station in my town and got to make friends with the tin knockers. I asked the forman if he could have the guys in the shop bend me a piece of steel. A couple measurements and a few days later, voila! I was ready to block the chimney. It was worth it to me. I have a freestanding stove in the fireplace not an insert.