Heat Shield

[redmiata92]

I have a used Jotul 450 C. Installing in the fireplace I have to create a heat shield. what should I use.

 

[BrotherBart]

Is it the mantle you need to shield?

 

[redmiata92]

No, not the mantle it is in the throat of the chimney.

 

[jqgs214]

Um, why would a chimney need a heat shield?? Is this not a masonry fireplace?

 

[redmiata92]

Well, maybe heat shield isn't the correct terminolgy. I mean the direct connect to prevent the heat from rising from the stove up the chimney. I believe it is a conversion plate or something.

 

[karl]

I think you're refering to a block off plate. Any fairly sturdy sheet metal will do. I used my damper plate. I cut hole in it, cut it in three pieces to make it easy to fit in and sealed it with stove cement.

 

[redmiata92]

Thanks. That's what I was planning to do, but with stainless steel, and in three pieces like you mentioned.

 

[Gooserider]

If you look in the hearth wiki you will find an article on making and installing blockoff plates. It sounds like you have the basic idea, the article may help with the details. Also searching the forums will bring up lots of discussions about the blockoff plates.

Gooserider

 

[Corey]

EEOUCH! Yeah, you may want to brush up on your terminology - "direct connect" is also a bit of a "naughty" word around here, too. : ) This refers to a pipe coming out of the stove/insert and only going partly up the chimney. It is generally regarded as being somewhat low on draft, poor performing, hard to clean, and less safe than the other option which is called "fully lined" - meaning you have a stainless steel liner running from your wood burner all the way to the top of the chimney.

Anyway - welcome! Snap some pics of your install if you have a chance. Preferably with a nice warm fire glowing in the firebox.

Corey

 

[redmiata92]

Yes, I don't prefer the direct connect, but for this season I will do it. However, wouldn't I still need a block off plate to keep the heat from rising. I know that surrounding the full liner there would be vermiculite but without a plate that would not be supported.

 

[BrotherBart]

Yes, I don't prefer the direct connect, but for this season I will do it. However, wouldn't I still need a block off plate to keep the heat from rising. I know that surrounding the full liner there would be vermiculite but without a plate that would not be supported.

With a direct connection you HAVE to have a tightly sealed block-off plate to keep flue gases from reversing and coming back into the living space. It needs to be sealed around the edges as well as around the flex/rigid pipe extended up into the flue tiles.

Holding in the heat is a secondary function of a block-off plate when you direct connect.

 

[Gooserider]

The disadvantages of the direct connect have been mentioned - depending on the size of the old chimney, it might not even be code compliant no matter what you do in regards to the blockoff plate. What is the flue size on your stove, and the tile size on the chimney? If the cross sectional area of the chimney tile is more than 3x the flue cross section on an interior chimney, or 2x on an exterior, then you should not do a direct connect at all.

The labor and cost of a liner install isn't that much more than a direct connect, so why not do it right from the beginning?

BTW, while there are cases where putting in a blockoff plate and pouring the chimney full of vermiculite around the liner is done, it isn't usually the preferred method. The reccomended approach is to wrap a special insulating blanket around the liner pipe, and cover it with a metal mesh "sock" that protects it and holds it in place. The liner plus blanket assembly is then lowered into the chimney. The vermiculite approach is mostly used only when there is some reason (usually the chimney being to small to fit a liner plus blanket, or excessively crooked, etc.) where it isn't practical to do the blanket.

Gooserider

 

[BrotherBart]

The vermiculite approach is mostly used only when there is some reason (usually the chimney being to small to fit a liner plus blanket, or excessively crooked, etc.) where it isn't practical to do the blanket.

Or when you happen to be pretty much anywhere in Europe.