Fireplace Insert

[Raspy]

Kenny,

That's pretty much how I see it too. Plus the new pipe has to be slid down the available opening. So 6" might fit easier than 8".

The insert that was already in my old house when I bought it had no new liner pipe up the chimney. It had a 6' round opening on top of the insert and just vented into the masonry chimney. It worked fine, but wasn't really right.

 

[dieselscout80]

Sorry, I missed the size and age in your original post. Most modern inserts have round outlets sized to use chimney pipe. I'm at a loss to know exactly how to size it but most wood stoves up to 100,000 BTU or over today have 6 inch pipe so I know it has a lot of capacity. I can't guarantee anything, but I can't imagine building a fire in an insert that 6 inch won't handle.

Kenny or Others,

I think I'm going to go with 6" for this reason. The exit of the insert is larger, but the opening to the exit is blocked by a plate that is mounted to back wall of the chamber at a 45ｰ to the top of the chamber (closer to the front of the chamber on the top). This plate prevents looking straight out the top of the insert and creates two opening to the exit that are triangular shaped 4"x7", so the two openings when combined equal a 4"x7" rectangle with a area of 28square inch just like six inch round pipe.

Would you insulate a liner in South Carolina note the existing masonry chimney is an exterior chimney see attached pic.

 

[Raspy]

No need to insulate the inner pipe or run double wall pipe. I've seen some flexible stainless steel stuff that can be snaked down the existing masonry chimney and past the damper assembly/smoke shelf. Then an adapter sits on top of the fire box to adapt the new pipe to the square opening. This can be crude, but must not interfere with the insert's damper.

At the top there is another plate the closes off the opening around the new liner and has a rigid pipe extending up a ways to accept the new cap. This can telescope over the flexible pipe. Finally a top goes on. You might need to seal around the top plate with concrete. The top can be round with a spark screen or it can turn in the wind to help the draft. The simple round ones are better if there is no draft issue, and I don't think you'll have any trouble with yours.

 

[dieselscout80]

Here is some measurements of the insert and pics.

Door opening 13"x20"
Firebox width 23" minus firebrick
Firebox height 20.5" minus firebrick
Firebox depth 18" (front to back) minus firebrick
Firebrick thickness 1.25"

First pic is looking down through the insert's flue opening.

 

[dieselscout80]

Here are a couple of pics of the inside of the chimney from top looking down and up through the damper.

 

[Yellowhair42]

I have a similar set up.First,I made an adapter out of stainless.Angle frame with plate top.My insert damper is just a sliding plate on top of the unit.I built the adapter to go around this and to go over it.Then I drilled and tapped holes every inch apart and bolted it on top of the insert sealing with furnace cement in between.So now I have a functional unit with a round tube coming up to recieve the liner.My original fireplace had a heatilator style with steel lining that had rusted badly due to no cap being on top of the chimney.This damage mostly occured before I bought the house.I totally gutted the inside of the fireplace and had nothing but brick left inside.My chimney is on the outside of the siding just like yours.My house was built sometime in mid 1800.I think the fireplace was built in the 60's.Anyway,I went to my local fireplace shop and bought a liner kit.I got the 8" but if you think about how much air is actually flowing through the unit I probably could have got the 6".My kit had a 20' roll of stainless flex pipe,a round to round adapter for the stove side,a cap plate for the top and a round slotted cap.Since my fireplace was already functional and the clay lined was OK all I basically was doing was making a route for the smoke to go through.If the stainless lined ever failed there was no worry of burning the house down.I put the liner down the chimney(very difficult)then connected to the stove.Then I went up on top and cut off about 5' extra liner.They actually let me return this and gave me back full value.Then I put the cap plate on and sealed it with red high temp RTV silicone.Lastly was just to put the cap on.

 

[lockhaven]

I cannot say enough good about Rockford. I recently had to replace my heatform fire place with a stove. The heatform had rusted out in the back and could not be repaired. I put a 6" flexible liner inside of my chimney, was easy to install and the directions were spot on. Being impatient to check the draw I lit a ball of news paper in front of the pipe, it burned like it had bellows pumping air to it. The people at Rockford were perfect in their support and information. I highly recommend them. Smoothwall Chimney Liner Kit - Smooth Wall Stainless Steel Flue Liner | Rockford Chimney Supply