New guy with smoke and heat question...

[NYC]

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.

[Les]

Originally Posted by david s

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]

Why do you find it amusing? Fill me in.

[brickie in oz]

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?

[Les]

Originally Posted by NYC

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]

Originally Posted by Les

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.

[NYC]

Do you guys feel that a larger chimney diameter would work or would it cause too much heat loss? Do I need to modify the chimney or completely change the design to an igloo with the chimney over an extended opening?

[david s]

Originally Posted by david s

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.

Victorian era fireplaces often had an adjustable entry into the chimneys so that not too much heat got lost once the fire and chimney were hot. You could reduce the enry adjustment and the fire still drew well, but at start up you had to have it wide open to prevent smoking the room. I think this is the situation with this oven, although it has no adjustment for start. Presumably the manufacturers designed it this way so not so much heat gets lost up the chimney.

[Les]

Originally Posted by NYC

Do you guys feel that a larger chimney diameter would work or would it cause too much heat loss? Do I need to modify the chimney or completely change the design to an igloo with the chimney over an extended opening?

Thats a significant modification. Opening up the hole size should be fairly straight forward. If you could install some type of damper to retain the heat, it would help. Although not ideal, it should allow the oven function.

[david s]

NYC,
Is the whole chimney length 8" with just the restriction at the entry to it? Or is the 8" bit only at the top?
If the major length of the chimney is the 4" diam. you'll have to go bigger.
Call the manufacturer of the oven. Did they specify a 4" flue pipe?