Using sheet metal to close fireplace opening

[mossycup]

I have seen this done on a few installs and we are planning on doing the same in our house.
A couple threads that show an example of what I'm talking about are here: https://www.hearth.com/econtent/index.php/forums/viewthread/42480/
https://www.hearth.com/econtent/index.php/forums/viewthread/43709/

We will be rear venting a Jotul F 500 Oslo into the opening of a solid masonry fireplace and chimney into the flue T. Aside from needing to provide an appropriate floor hearth, any combustible surfaces are well away from the rear vent connector and stove. We want to cover the opening with sheet metal until we remodel the room and reface everything with stone or tile.

We are planning on adding the Jotul rear heat shield to the stove for reduced rear clearances, but since it will be in front of a hollow, metal faced cavity, it seems moot. Anyway, I am on track with the chimney but the connection between the stove and the T are my concern. If I just use single wall pipe as the rear connector, my assumption is that I can just pass it right through the sheet metal with minimal play and apply a sealant and a decorative cover if needed. Basically, I've been eyeing the same procedure that the NFPA 211 requires for the damper opening to be sealed with sheet metal...it doesn't seem any different.
-Would a gap around the pipe be necessary?
-Am I better off to use a double wall rear vent connector?
It seems that no matter what, the sheet metal is going to nice and hot.

 

[mossycup]

Just a bump so this doesn't get buried.

I am hoping to visit the dealer this weekend and lock into one of the matte black F 500s that they still have, but I want to have my shopping list fine tuned.

My wife wants the Majolica Brown floor model and I want to put the debate behind us;-)

 

[wkpoor]

Well I don't have any advice but I'm thinking of doing the identical thing only I've got a pre mfg fireplace with a double wall air cooled pipe to plumb into. I have the same concerns as you. One thing I would mention is the serviceability of the install. I wouldn't think anything needs to be sealed. My thoughts are to install a thimble in the plate to connect the stove pipe to. The fireplace side of the plate will have an insert type fitting to allow a tight connection when the plate is installed.

 

[begreen]

I have seen this done on a few installs and we are planning on doing the same in our house.
A couple threads that show an example of what I'm talking about are here: https://www.hearth.com/econtent/index.php/forums/viewthread/42480/
https://www.hearth.com/econtent/index.php/forums/viewthread/43709/

We will be rear venting a Jotul F 500 Oslo into the opening of a solid masonry fireplace and chimney into the flue T. Aside from needing to provide an appropriate floor hearth, any combustible surfaces are well away from the rear vent connector and stove. We want to cover the opening with sheet metal until we remodel the room and reface everything with stone or tile.

We are planning on adding the Jotul rear heat shield to the stove for reduced rear clearances, but since it will be in front of a hollow, metal faced cavity, it seems moot. Anyway, I am on track with the chimney but the connection between the stove and the T are my concern. If I just use single wall pipe as the rear connector, my assumption is that I can just pass it right through the sheet metal with minimal play and apply a sealant and a decorative cover if needed. Basically, I've been eyeing the same procedure that the NFPA 211 requires for the damper opening to be sealed with sheet metal...it doesn't seem any different.
-Would a gap around the pipe be necessary?
-Am I better off to use a double wall rear vent connector?
It seems that no matter what, the sheet metal is going to nice and hot.

Clearance requirements are from combustibles. I can't see any need for the rear heat shield or other concerns with a masonry fireplace behind the stove. Adding a metal cover for the fireplace opening doesn't change that. The mantel might be the only thing to check.

The pipe opening can be tight to the pipe. Sheet metal is thin and doesn't have the mass to store much heat.

 

[ecocavalier02]

i just cut the piece at my shop then 2 coats of high heat spray paint

 

[mossycup]

So if I have this straight, single wall connector is fine-I can make the hole snug to the pipe-sealant just be cosmetic and firm up any sheet metal flex , and decorative ring as desired?

Mantle is concrete, so we're good to go!

This is how I summed it up in reading the codes, no combustibles are involved. It just wasn't clear, thank you.

 

[ecocavalier02]

Sounds good to me

 

[mossycup]

BTW, is plain steel sheet metal preferred or is it safe to use HVAC grade, zinc (galv.) sheet metal as long as no vent gasses contact it?

 

[Milton Findley]

I would recommend against the zinc due to the possibility it might get hot next to the pipe. I used a 24 x 36 inch sheet of 24 gauge aluminum, cut up the center, with half circles cut out at the location of the stove pipe. I pop riveted a sheet of decorative aluminum screen, with gold anodizing on it, to the front of the aluminum. The old fireplace opening was 24 x 35.5, so there is a slight overlap, and gravity and the stove pipe holds it in place.

This looks pretty good in my opinion, of course. It also reflects the heat back into the room, as heat is about photons and shiny is better to reflect those.