New guy with smoke and heat question...

[brickie in oz]

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

Sounds like you have been dealt a dud with no insulation.

The outside of my oven gets 10 degrees above ambient temperature when its 600c inside.

[NYC]

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

The oven "kit" has I believe a 3" thick rebar reinforced high heat concrete shell and the floor has the same type of slab underneath the firebrick for a total of about 5-6". The dome has just the natural stone cemented to it with high heat mortar. I shot the dome with an IR during use which only goes up to 560 deg and the dome was def higher. The floor would go to about 500-550 in some spots and higher in the spot directly under the fire. The outside stone on top of the dome was at about 140deg as was the outside part of the stone on the chimney stack just above the dome.

[DrakeRemoray]

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

Before you worry too much about retained heat cooking or pizza temps, we should ask about insulation. Do you know if they put insulation directly under the floor of the oven and over the dome? If not, I would focus on knocking down your chimney (sorry) and putting in an 8" flue as recommended. You will be able to cook pizza but may have trouble getting to 700 degrees without the proper insulation and with that vent(less) design.

If the oven is properly insulated underneath and in the dome, it is probably worth the effort to knock down the existing chimney (sorry again) seal up your existing flue hole then build out a vent and landing in front of the existing oven. Then put in a properly sized (8") flue on that and angle the chimney back so it goes out the same hole in the roof.

That said, if you let the oven dry more with smaller fires, you will probably find that it only smokes for the first 10 minutes or so once it is properly dry...

Do tell us about the insulation though...

Sorry for your troubles.

[david s]

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

If you explain that the oven is unusable in the present configuration, they should replace it with an 8" flue, but will you have room to install the wider pipe?

Having had experience in building both updraft kilns and ovens I have found that they work quite adequately. They draw beautifully, much better than a crossdraft (FB Pompeii style) provided the flue is an adequate diameter. It is the column of rising hot air that gives the flue its power and a smaller restriction at the bottom is not as important as the total volume in the flue itself. A great advantage of the updraft design is that you don't have a deep entry to have to work past when putting stuff in and out of the oven. There were a number of updraft ovens at Pompeii (usually smaller) The downside is that they do use a bit more fuel. You can still achieve pizza cooking temps. with ease and if you have a system of shutting the flue you can also do plenty of retained heat cooking.

[NYC]

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

Yes that is my exact oven make and model.

[shuboyje]

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

Maybe I should look at a link again before posting it. If your oven is indeed the same model there may be some hope. That thread shows the flu opening insert in a larger square opening. If you opened up that square you could probably run a masonry chimney that would do the trick using square clay flue liners. That wouldn't fix the other issues but it would fix the smoke problem. Outside the smoke problem and huge wood consumption this oven does work according to the user in the other thread.

[shuboyje]

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

You might be interested in this link:

The Big Guy! Precast Barrel oven

Personally I would open the enclosure back up, fill the current vent with castable refratory, install an entry and a proper 8" flu, and then going after the manufacturer to cover the cost. They supplied the whole flu, so they knew the application and should have known you would have smoke issues, this is glaring issue with this oven.

[NYC]

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

That's what I was afraid of. You buy a prefab kit to take the guesswork out of it and it turns out to be all wrong. What a major disappointment.

[lwood]

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

NYC, the hole in the top of the dome is a show-stopper. The 4" flue could be replaced easily enough, if it were in the right place. Who ever built this oven for you, obviously never made it work. There is no way you will ever get it up to 700F to cook pizza. A exhaust fan will just pull the heat out of the oven. Bring the guy back and ask him to make it work or....just rebuild.

[david s]

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

If you explain that the oven is unusable in the present configuration, they should replace it with an 8" flue, but will you have room to install the wider pipe?

[NYC]

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

Entire flue is 4" ID and manufacturer supplied.

[david s]

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

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?

[Les]

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

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]

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.

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.

[NYC]

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

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?