New to wood burning...want to DIY Osburn 2400 insert some info neeeded

[Capetownkg]

Hi everyone. First off I love all the great info on the site and all the help people seem to lend. That being said I am very close to buying my supplies for a DIY osburn 2400 insert install. I have read a lot of info and have the basics down (or so i think). First off let me describe the house 2100 sq ft colonial,chimney is on exterior wall, 20ft tall, terracotta tile lined. That all being said I know i am going to install an insulated 6" flexible chimney liner. My first set of questions is how do I know where to cut the opening and what size to cut it to in my fire box. My damper is fairly large but I know I will have to open more up. Then I have heard talk about a backplate and having to customize them. What is the best way to seal the opening and how do i go about doing it properly? I just dont want to open up to large of a hole or way bigger then i need to. Thanks for the help, I know I have lots to learn and i look forward to it.

 

[begreen]

Welcome to the forums. Have you checked to see if the damper is removable? If it is, I would think that would give you the clearances you need. Otherwise, measure twice and cut once. Make a template or cardboard mockup of the insert if it helps get an accurate position for the flue outlet. If there are complications, can you post some pictures of the issues and the fireplace? Here is a link on damper sealing block off plates:

https://www.hearth.com/econtent/index.php/wiki/Why_damper_seal_is_needed/

 

[Capetownkg]

Looks like I can remove the damper but the measurements for the damper plate are 27" long by 5 3/4". Is it possible to squeeze the flex liner through that or would squeezing it affect performance? Not sure how much those pictures help out. If i take the damper plate off i would have a lot of room to the sides of the liner that would need a good sized back plate for both sides.

 

[wh401]

I'm new as well and currently working on installing the liner for my new insert. I have the same issue, a damper opening that's too small for the flex. IMO, cutting the damper to provide enough opening for the liner would be the best option. Pinching it through the opening is going to cause a large kink in the flex and will most likely effect the air flow a good bit. I'd opt for a cutting wheel on a 4" angle grinder, (with all necessary safety equipment), and cut enough of a "V" on the front and back of the opening to cleanly run the flex, (with insulation) through it. The 2400 is fairly large insert and I believe it goes back in the fireplace by a fair bit. As mentioned above, the location of the cuts may need to be more to the front or back of the damper to allow for a good angled connection to the insert. Best of luck.

 

[Capetownkg]

Thanks begreen that link for the block off plate is stellar!

 

[begreen]

Looks like you may want to take an angle grinder or sawzall to the center area to make passage for the liner.