Newbie -- How to connect stove to cast-in-place liner?

[foxfield]

We are installing a Jotul F500 Oslo woodstove in a 170-year old masonry fireplace. The chimney has a 7-inch round cast-in-place Supaflu liner already installed. The base of the liner is about 80 inches above the top of the stove and is offset about 20 inches from where the stovepipe will connect to the stove.

Thanks to this forum, we have had most of our questions about the chimney, clearances, and floor protection resolved. However, we still have questions about the best way to connect to the cast-in-place liner.

Here are some of the options we have considered:

1. Insert a piece of 7-inch stovepipe into the liner opening. Seal it with appropriate sealant. Attach a 6-to-7 inch adapter. Run the stovepipe from the stove up to the adapter using appropriate elbows for the offset.

2. Insert a piece of 7-inch rigid stainless steel flue liner into the Supaflu opening. Seal it with appropriate sealant. Attach a 6-to-7 inch adapter. Continue downward with 6-inch rigid stainless steel flue liner using elbows for the offset to a point that it is out-of-sight behind the lintel (about 30 inches). Then continue straight down with stovepipe to the stove.

3. Insert a piece of 7-inch rigid stainless steel flue liner into the Supaflu opening. Seal it with appropriate sealant. Attach a 6-to-7 inch adapter. Continue downward with 6-inch flexible stainless steel flue liner to a point that it is out-of-sight behind the lintel (about 30 inches). Then continue straight down with stovepipe to the stove.

We would appreciate your opinions and advice.

Thanks.

 

[branchburner]

I'll take Door #3.
I'm wondering about ease of cleaning - would it make sense to continue right down to the lintel with 7" ss liner, then the adapter, then the 6" stove pipe? That way you could sweep the whole liner with a 7" brush and remove the short length of 6" pipe at the lintel to clean seperately.
Have you consulted Supaflu (or other cast-in-place) literature for best connection scenarios, or called Jotul?

 

[BJ64]

My turn!

Greetings and welcome! Congrats, you have a nice stove.

Here are my expert qualifications : None - but I read a lot on here.

How about dropping a 6 inch liner down the 7" stack? That way the stove has the 6 inch vent system it was made for.

I have learned that bigger is not always better concerning chimney. I am wondering if the old 7 inch would cut down on the stove's draft force. On the Oslo it may not make much difference but I don't know off hand.

 

[begreen]

I'm confused, why would they stop the casting 80" above the fireplace opening? Is it just raw bricks in the chimney throat below the SupaFlu? Maybe a picture will help.