Should I insist on a block off plate

[gixxer340]

I will be having my Jotul fireplace insert installed in the next couple of weeks and, when I was talking to the stove place, they said that they don't usually install a block off plate. They said that that they just put insulation above the stove. Will this be enough to keep the heat from going up the chimney? The fireplace opening that I have is pretty large in comparison to the unit so there will be quite a bit of airspace around, and especially behind the insert. I just want to get as much heat out of the unit as possible and I am afraid that, if I can't get them to install the plate, I will be doing it myself later on.

Thanks for any advice
Jeff

 

[Nick Mystic]

I think the reason stove shops routinely say they don't install block off plates, just stuff insulation up the chimney, is due to money. Businesses want to make as much money as they can and installing a block off plate is a bit of an unpredictable job since each installation is a custom fit job. Customers want to have a bottom line price before signing a contract and stove shops don't want to risk having a block off plate complication add 2 or 3 hours to their labor cost that would eat into their profit. To keep customers happy they tell them a block off plate isn't really necessary since they put on a top plate, or they put insulation up the chimney, etc.

The consensus here at the forum seems to be that installing a block off plate is the best way to go to maximize stove/insert heating. So, if you can't reach an agreeable price for the shop to install a block off plate you will need to do it yourself or hire a different "handy man" to do it. I installed a block off plate when I did my own stove installation a couple of years ago. It can be a tedious process and you need to have to good mobility since you are working inside the confined space of the fireplace opening and all the work is above your head as you crouch down inside the firebox. There are several threads at the forum that describe different methods of installing a block off plate. Good Luck.

 

[mstoelton]

My experience was the same when I installed my first insert. I could not find anyone local that would install a block-off plate. I had to do it myself. Many contractors don't want to spend the time or effort to do it right. Each block off plate is different, and has to be custom fabricated.

I believe that a good tight block-off plate is one of the keys to getting the maximum heat from an insert.

So yes if you can find someone to do it, insist on a block-off plate.

The last one I made took several hour extra. The fab shop cut the metal plate to the wrong size and made it from 18 guage steel instead of the 22 gauge I requested. I got it installed but it was a bear and took 5 hours for the plate.

 

[weatherguy]

Is the that the name of the place you're getting your stove from? If they won't do it just buy a piece of sheet metal from Home Depot, its under $10 and read one of the threads here on how to make it. In fact before they come for the install buy the sheet metal and ask them to do it. They should be able to do it fairly quickly and for not too much extra.

 

[Jags]

A block off plate is highly recommended. They are not difficult to make if you can't come to an agreement with your contractor.
https://www.hearth.com/econtent/index.php/articles/making_a_block_off_plate/

 

[Lumber-Jack]

I am afraid that, if I can't get them to install the plate, I will be doing it myself later on.

Thanks for any advice
Jeff

You don't really mention installing a liner?
You'll want to be installing the block off plate before installing the stove. If you wait to install the block off plate you likely have to remove the stove again to get access to the chimney. Much easier if you can do it before installing the stove, in fact if you are thinking to do it yourself why not fit a block off plate now and all they'll have to do is cut a hole for the liner to slip through when they install the liner.
You'll still want to put some insulation up there even with the block off plate.

 

[begreen]

If this is an exterior wall fireplace you will appreciate having a proper block-off plate with Roxul insulation stuffed above it. That will keep the stove warmer and thus putting more heat into the room space. There's no point in heating outdoors.

If this is an interior fireplace there may be less gain and simply stuffing some insulation around the flue in the damper area is probably sufficient. The heat that does go up the chimney will warm up the masonry and will slowly release back into the house as the stove cools down.

 

[gixxer340]

Thanks for all the input. I will definitely be trying to make one of these before they come to install and trying to get them to install it while they are there. The stove place that I purchased the unit from (and that is doing the install) is New England hearth and home in Canton MA. Hopefully they do a good job with the installation. I plan to be home when they do the install so I can see how it is done in case I ever have to do it again.

Thanks again for the input
Jeff

 

[bholler]

Are they insulating the liner?

 

[gixxer340]

Are they insulating the liner?

I don't believe so. What does this entail exactly? Literally stuffing insulation down the chimney around the liner? I can ask the installer

 

[bholler]

In a fire place it would usually mean wrapping the liner in 1/2" foil faces insulation. It gives you a big improvement in performance and makes it so you dont require any clearance from the outside of the masonry structure of the chimney to combustibles. Honestly if they will not insulate or do a blockoff plate i would be looking for a different installer

 

[lml999]

Thanks for all the input. I will definitely be trying to make one of these before they come to install and trying to get them to install it while they are there. The stove place that I purchased the unit from (and that is doing the install) is New England hearth and home in Canton MA. Hopefully they do a good job with the installation. I plan to be home when they do the install so I can see how it is done in case I ever have to do it again.

Thanks again for the input
Jeff

I think I bought my stove from them a few years ago. I'm in the middle of a blocking plate installation, will have some leftover Roxul available this weekend. You're welcome to swing by and grab some for your project... PM me offline...

 

[brenndatomu]

I will definitely be trying to make one of these before they come to install

You will need to make the hole for the chimney liner a little on the big side to allow for some adjustment for final stove placement. You can use a stove pipe trim ring to cover the oversize hole up. Or, you can install a plate after by making a two piece plate that overlaps in the middle, held together with screws or pop rivets.

 

[gixxer340]

I think I bought my stove from them a few years ago. I'm in the middle of a blocking plate installation, will have some leftover Roxul available this weekend. You're welcome to swing by and grab some for your project... PM me offline...

Thank you very much for the offer. I talked to the installer today and he is going to put in a lower block of plate so I shouldn't need the material. He is still very insistent that the insulation is not needed as long the clay tiles are in place and in good condition. I am going to check with the local house inspector to see if it is required by code but, if it isn't, I am going to go with the installers recommendation. Unless, of course, there is an absolute necessity to push them to install it. If I do insist on the insulation then I will probably have to pay extra for it.

The chimney is on an exterior wall except the garage and addition above it were built around it. It does still reside in an unheated garage and storage space though off the master bedroom. It is also a double flue chimney that has a second flue that is used for the oil furnace.

Thanks for all the help so far

 

[brenndatomu]

Any idea how tall that chimney is? Modern stoves run much better with a insulated liner when using a exterior chimney, especially if the chimney is not real tall. Would likely cost $200-300 more...

 

[Ram 1500 with an axe...]

I have cob webs behind the front of the insert in my fireplace, the only place there is heat, it is going up the 6 inch ss pipe so I'm not sure what a block off plate would do for me.... I have no heat radiating off my insert and going into the brick walls or up the chimney, I can also put my hand on top of my insert back in my fireplace.....just saying.....

 

[bholler]

http://www.rumford.com/code/clearances.html
If irc is code where you live which i believe it is it is required by code regardless of the condition of the clay tiles. It will probably work fine without but it is not to code unless you have the required clearance form the exterior of the masonry to combustibles. And it will work much better with insulation. And yes ram 1500 with an ax is just about the only one here that will argue that block off plates are worthless. And by the way those cob web are there because of he air movement caused by tthe lack of a blockoff plate

 

[brenndatomu]

I have cob webs behind the front of the insert in my fireplace

I dunno, never tried it, but I have heard from various places that heavy cobwebs are very flammable...?

 

[Ram 1500 with an axe...]

I dunno, never tried it, but I have heard from various places that heavy cobwebs are very flammable...?

The fact that I have cob webs back there means that it is not hot back there and I may not need a block off plate because I am not losing heat back there......

 

[bholler]

Why does that mean it is not hot back there?

 

[Ram 1500 with an axe...]

Why does that mean it is not hot back there?

It means I'm not losing heat from the top or sides of my insert that is located inside my fireplace....

 

[bholler]

I get that is what you are trying to say but your reasoning doesn't make sense. I have cobwebs behind my stove and believe me it is hot there

 

[Lockpicker]

If your local building inspector says uninsulated is OK as well as your installer. Then I would say your situation doesn't call for the extra expense of the material and the possibility of tearing out the existing flue liner to fit 1/2 inch of insulation. First let me say this site is an invaluable resource of information. Love this site! That said,,, Don't let some of the people on here scare you into something you don't need. There is a thread here where the installer said the homeowner only needed an ember protection hearth. Before long the experts here had this poor women tearing out a brand new masonry hearth with everything from sawzalls to jackhammers.telling her the hearth was not done right. In the end it turns out the installer was correct and it only needed ember protection. Lucky for the homeowner at least one person here knew what he was talking about.and saved her from ripping out the new hearth the experts here told her to rip out.

Sometimes it seems that every person that asks about an install here is told the installer is ripping them off or not doing the job right. Gets old.

Thread here.
https://www.hearth.com/talk/threads...ith-pix-and-desperate-plea-for-advice.132704/

 

[lml999]

The chimney is on an exterior wall except the garage and addition above it were built around it. It does still reside in an unheated garage and storage space though off the master bedroom. It is also a double flue chimney that has a second flue that is used for the oil furnace.

Thanks for all the help so far

The unheated garage mitigates your need for insulation. In my case, my chimney is (mostly) on an outer wall, and has a decent size cavity behind the firebox. About 4 feet away a part of the chimney is exposed in another room, and after hours of use, that chimney gets pretty warm to the touch. This tells me I'm using BTUs to heat up that uninsulated space, losing much of the heat through the exposed brick to the outside. I'm adding as much insulation as I can into that cavity, then finishing it off with a blocking plate.

I've been reading threads about lining the sides of the fireplace itself (not the stove!) with the sheet Roxul and sheetmetal, been thinking about doing that too, but not sure it will have as much impact. It would tend to direct heat into the room rather than heating up the fireplace bricks...

 

[bholler]

If your local building inspector says uninsulated is OK as well as your installer. Then I would say your situation doesn't call for the extra expense of the material

I agree totally if the local inspector says it is ok it is but i just checked and irc is the accepted code in ma with a few amendments which don't say anything about chimney construction. So the code that i posted is the code in ma and if the inspector knows what they are doing they should require insulation unless those clearances are met which is rare. Just because the installer says it doesnt need it does not have any bearing on the code at all.

And that thread about the earth was dur to a confusion because the model number that that homeowner had required more than ember protection what people here did not know was that a long leg kit was installed making it require only ember protection. I am sorry but here all we have to go by is what the manuals say we are not there to see it so questioning that install was the right thing to do and it all worked out in the end.

I really dont understand why you Keep insisting that the code i am quoting is not valid with no info backing your claim whatsoever. If you have that info post it if i am wrong i will gladly admit it but i am not in this case