When you install a fireplace insert with a stainless steel chimney liner, you should install a block off plate.  The block off plate is a horizontal plate that blocks off the opening where normally a damper is in a fireplace.  This opening will vary in size, but generally you will be installing a 6″ or 8″ chimney liner.  When you have such a large opening around the liner, a large amount of the hot air generated from the wood stove will be rising up into the chimney cavity.

To prevent this from happening install a block off plate.  They are almost always best to be fabricated on site.  This is because the block off plate will be different for almost every fireplace.  The block off plate will have a hole in the center of it that is slightly larger than the flue liner you are using.

To build a block off plate follow these instructions.  Basically made a cardboard template, to get the proper angles and perfect size, cut enough extra for the flanges to mount the block off plate and transfer the template to sheet metal.

block off plate








    *Note: If you have a terra cotta clay chimney
    flue lining, be sure to measure the true length and width of the
    inside of your chimney flue space.

    *If there is a terra cotta clay flue liner, does it protrude out of
    the top of the chimney at least 2 inches? If there are at least 2
    inches and the terra cotta clay is in good condition, you will use
    our stainless steel, terra cotta top plate that has a 1 1⁄2inch edge
    that goes all the way around (like a shoebox lid).

    *If your terra cotta clay flue is in bad shape at the top, you may
    need to just take a hammer and tap all around that terra cotta,
    taking it away to make the surface flat at the top of your chimney.
    In that case, you will simply use the flat top plate that comes with
    our liner kit.



    *Note: If you have a terra cotta clay chimney
    flue lining, be sure to measure the true length and width of the
    inside of your chimney flue space.

    *If it is on the back of the stove, is it parallel with the back of the stove or is it at an angle, like 45 degrees?

    *If it is at an angle you will use an insert stove adaptor (an insert liner kit) rather than a two-part tee with cleanout cap.


    Usually pellet stoves have an exhaust hole id of 3 inches. However, if you are going up more than 15 feet to the top of your chimney you need to use a pipe and/or flex liner that is 4 inches diameter.





    If you are only venting a hot water heater then the exhaust hole diameter is probably 3 inch diameter. If it is 3 inch diameter and you are going up more than 15 feet to the top of your chimney, you must use a 4 inch diameter flexible liner or ridged pipe for proper draft. We also suggest to go ahead and use a 4 inch diameter flexible liner or ridged pipe even if the total length is 15 feet or less.


    Not the depth or any other dimension inside your fireplace.

    Most gas log fireplaces require an 8 inch liner kit or rigid kit. But do not assume that is the case for the gas log fireplace kit you are installing. Obey the requirements for that specific unit that are in your installation/instruction manual.

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