New guy with smoke and heat question...

[brickie in oz]

Re: New guy with smoke and heat question...

I'm not sure it works that way.

Me too, its not like a venturi in a carburetor that has a sucking force of an engine to draw the smoke.
The smoke will find the easiest way out which is the oven opening.

[Les]

Re: New guy with smoke and heat question...

Why do you find it amusing? Fill me in.

Stone age - like not understanding physics - Oklahoma, nuff said. (I am not slamming the good people from OK - it's just embedded in the American vernacular)

[brickie in oz]

Re: New guy with smoke and heat question...

Apart from remodeling the oven the exhaust fan you linked to may be the go.

As a rule of thumb the flue shouldnt be less than 10% of the oven/fireplace opening size to work efficiently, more than 10% is better.

Edit.
I just looked at your flue pic, how far from the top of the flue is the rain stopper?
Is it too close and stopping the smoke?

[NYC]

Re: New guy with smoke and heat question...

Why do you find it amusing? Fill me in.

[Les]

Re: New guy with smoke and heat question...

Although the 4" restriction is not helpful at start up, if it has an 8" flue beyond the 4" restriction.

I'm not sure it works that way. It's like feeding a 2 inch water pipe from 1/2 inch. Does nothing for the volume at the output. I would personally take off the flue and use an angle grinder to get it to a proper size. Remove the restrictor plate if you will (for you NASCAR fans). You still have the issues that David (Dmun) pointed out in regard to the location of the vent. I find it a little amusing that it was built by Stone Age manufacturing in Oklahoma (sorry).

[NYC]

Re: New guy with smoke and heat question...

Thanks for all the good feedback. Needless to say I am less than happy right now as I did spend a ton of money and right now this oven is a pretty paperweight.

I need to find a solution.

[david s]

Re: New guy with smoke and heat question...

Before you start pulling that oven apart, why not try firing it some more. If it is new and wet it will smoke more. Although the 4" restriction is not helpful at start up, if it has an 8" flue beyond the 4" restriction, the flue should draw pretty well once it has heated up. Keep the fire small enough so it won't smoke, for at least half an hour. This should be enough time to heat the flue which will create drawing power. Presumably the manufacturer has sold plenty of these ovens and they work. Contact them for assistance before jumping in to rebuild.

[dmun]

Re: New guy with smoke and heat question...

Can you integrate an exhaust fan into the 8" flue?

You could but you shouldn't need to. A through-the-ceiling run of 8" flue should draw like a locomotive. Exhaust fans are used in commercial locations where there needs to be a long horizontal run of flue.

As multiple posters have pointed out, it's the four inch hole. It's the wrong size and it's in the wrong place.

[Faith In Virginia]

Re: New guy with smoke and heat question...

I don't know if an exhaust fan in the flue would help much because your still dealing with the 4 " restrictive oven opening. I would also be concerned about heat issues on the fan it's self and would need to check the heat operating range of the fan.

As far as the vent hood goes I think you could get away with placing it higher then forehead height. I think if you went up some it would be fine. The pan shape of the covered area looks like a great place to trap smoke and in turn make the vinyl look dingy in short time so a vent hood would help even after the chimney is fixed.

I know this idea sucks but I would think that 4" hole needs to be fixed by taking down the chimney and cutting a larger hole then rebuild the chimney. I don't know if that is the right answer but it is what I would do.

[ebbro]

Re: New guy with smoke and heat question...

Can you integrate an exhaust fan into the 8" flue?

[dmun]

Re: New guy with smoke and heat question...

Flue at the top of dome: Really bad practice, impossible to reach heat with a reasonable amount of wood, impossible to do retained heat cooking, but shouldn't effect draw.

I am extremely suspicious of a four inch round flue for a 42 inch square oven. Even with that long a chimney, that's going to belch smoke on startup. FB recommends an eight inch flue, almost three times the area for a 42 inch round oven. Also there's no transition, just the four inch hole in the top.

What would I do? Well your options aren't great. I'd start by blocking up that useless little hole at the top of the dome. You could build out your oven floor and build a proper firebrick entry with an eight inch flue at the recommended 2/3 height of the cooking chamber. Faith's idea is a good one as well: Have a stainless hood fabricated, and vent with stainless flue units, which could be elbowed to go through your existing hole in the roof. This is less than ideal because it puts a blisteringly hot hood at forehead height while you're cooking. Perhaps the fabricators could make a double layer hood that could be filled with loose vermiculite.

You obviously spent a ton of money on this project. You would expect someone selling modular ovens would have at least some idea of how an oven works. If they don't know where and how an oven vents, I'm wondering if they know anything about insulation.

[lwood]

Re: New guy with smoke and heat question...

That is your problem. 4" is too small. Can you give us some pics of the transition area?

[NYC]

Re: New guy with smoke and heat question...

The top piece is one we added to use the cap and it has an 8" OD. The flue from the oven is indeed a 4" ID.

[Faith In Virginia]

Re: New guy with smoke and heat question...

I think David S has a great point. 4" flue is small for the oven size. I would agree that this is most likely the cause of your smoke issues coming out of the oven door. I would check that your oven has this small opening because you do have a sufficient chimney pipe coming out of the roof. If the opening is 4" do call the manufacturer.

[david s]

Re: New guy with smoke and heat question...

NYC,
Looking at the plans from the manufacturer, it appears that the flue diameter is only 4"
Even though this is an updraft design a 4" flue is way too small for an oven this size IMHO. Why don't you contact the manufacturer with your problem?