Cover fabricated vent or not?

[TommyTongue]

Hi .. So I have decided to get the vent fabricated rather than build it from brick or cast it.

Firstly is thin stainless steel appropriate? i.e the stuff used in residential homes for heating vents. If not what material should be used. I can get an HVAC guy to knock 1 up quickly and quite cheaply.

Secodly do I have to insulate it and cover it with render or can it be left "un insulated" as it will look quite nice. But thin metal and heat loss im not sure about.......

I have attached pictures of the build with a model of the vent and with out, for refference.

Also I have used the draw spread sheet and based on that I should be using 8 inch chimney pipe to get a good draw. However the oven is only 30 inch inside diameter. The opening is 18 inch wide and 12 inch tall... The vent opening is 10 inch deep. As per the photographs

Would 6 inch be better again Im thinking heat retention........... but is it better to go bigger diameter? Hope this all makes sense.

Any advice would be appreciated.

Thanks....

P.S sorry about the dog. He was inspecting the work done!

[david s]

The fabricated metal hood is fine, but for a 31” oven a 6” diameter pipe is adequate, you could probably get away with 5”, no need to go to 8”.
The smaller diameter pipe means you can make the entry shallower and easier to work the oven.

[TommyTongue]

Does the metal hood have to be insulated and covered. Or is it fine to leave it as is?

[UtahBeehiver]

An uninsulated hood is fine. Just to be sure, most all HVAC duct work in the US is galvanized steel not stainless steel. Galv. steel is not recommended.for WFO

[TommyTongue]

An uninsulated hood is fine. Just to be sure, most all HVAC duct work in the US is galvanized steel not stainless steel. Galv. steel is not recommended.for WFO

Why is that?

The quotes im getting are insane in price for ironand stainless steel. Like over $1000 buks....Brick is way way cheaper.....

[UtahBeehiver]

Maximum temperature for galv. is around 400 f. If you look at any chimneys made for wood fuel operation the inner wall at a min is ss and most times both walls are ss. Also galv will give off toxic fumes if it gets hot enougn.

[TommyTongue]

Maximum temperature for galv. is around 400 f. If you look at any chimneys made for wood fuel operation the inner wall at a min is ss and most times both walls are ss. Also galv will give off toxic fumes if it gets hot enougn.

Toxic fumes doesnt sound good. I assume the vent is going to get hotter than that next to the oven.

Well think its brick then.
I really wanted the clean look of a fabricated vent and the efficiency. Never mind. Cost wins again!...lol