Bread Oven Chimney

You have overwhelmed us with information.

Yes, you need a chimney.

How'd that ice making machine work out?

A: Safe hood. B: Chimney. C: Flow regulator. D: Door. E:Thermometer. F: Tempered glass window. G: Hand grip. H:Base support.I: Fuel entrance (firewood chamber).J: Entrance for air and cleaning ashes. K:Grill. L: Heat-resistant clay.M:Fasten bolt for removable part.
https://energypedia.info/wiki/Baking_with_Improved_Ovens

If you intend to use the gas oven and burn gas then of course you need a chimney.

Its the same as the exhaust pipe on a car. Only you don't bake bread with the car...

When you say you design it and are about to construct it, did you take the time to learn about designing and constructing first?

I'd call it a design standard for an oven to have a chimney.

thanks all. Iyn d ice machine project is suspended for now.

Got me thinking. A domestic gas oven doesn't have a chimney as such. It must draw in combustion air and exhaust warm air, just into the room, not vented to outdoors as far as I know. So I'd say it depends how big your oven is and whether the heat input to the room you're putting it in would be a problem. Anybody comment?

I think you are wrong. While a gas stove does not have an exhaust the oven should have a connection to the chimney. Venting into a kitchen could become very dangerous.

At least the oven we had in the past was connected to the chimney.

And nowadays gas stoves come with a electric over for the exact reason.

But I am not OP so its worth walking into a shop to see or employ the WWW for quick answers. I might give it a shot later . . .

I could be wrong. The last gas oven I had I'm fairly sure did not have a flue to outdoors, but it was installed ~ 20 years ago and maybe regs (UK) have changed. Had a look on the web and not easy to find anything definitive but it doesn't seem to require it.

Of course it might be different with bigger commercial ovens (as I said in #5), as usual we need more information from the OP.

Are you willing to bet that it'll be adjusted properly. Not having it vented, there has to be contingencies to be met, because there are already compromises.

More information is needed, Look at NFPA 86. I don't have mine immediately available.

If you bake a few loaves of bread a week, you're probably right.

If this is a bakery that is just baking bread and cake every day, then yes, a vent/chimney is needed.

Granted the OP provides no useful information beyond, "baking bread and cake."

One has to keep in mind, that the exhaust may not be on the oven, but on the exhaust hood above the oven.

The cooker I referred to in #11 (gas oven plus 4-ring gas hob) didn't have a new-fangled contraption like an exhaust hood .

Domestic natural gas ovens do have a chimney, just not the type that is ordinarily though of. With the complete combustion of natural gas there is less heat and gases that need to be exhausted. Manufacturers disguise slots in the "splash panel" both front and back, to vent the combustion products and gases (look closely at your stove). Since there isn't much of it much smaller ones and easier to disguise ones can be used. These are more noticeable as slots/louvers in the front of "back splash" on older stoves. If you baked something and has an oxygen meter in the room the level would lower from the normal of 20.9% to a level lower than that as the oxygen is used up. The higher the heat of combustion, the faster the oxygen is depleted for internally vented appliances. This would happen quicker in a well closed off house with a small size interior. A house with many outside air leaks in and of a McMansion size would possibly have the change not noticeable. Most residential stoves put out between 7,000 to 12,000btu/hr. maximum. The ovens put out about 15,000 to 16,000btu/hr. A residential gas dryer has an input of about 30,000btu/hr and its combustion gases are vented through a chimney.

Large commercial stoves/ovens are vented with a hood and ducts to the exterior or a chimney directly of the stove to the exterior. Next time you buy a pizza pie from a shop with a gas fired oven look for the chimney!

Coal and wood stoves require a chimney since they produce much more combustion gases.

Good Luck, Old Salt

That's right, it's just that I don't think the warm air from the slots goes into the room with a normal domestic gas oven, not vented outdoors.

So I think the answer to the OP is - he might get away without a chimney, but it depends on oven size and various other details.

I checked 3 residential and one commercial ovens this evening. All the residential ones were vented through slots in the upper back panel. The commercial had a chimney as well as a hood which exhausted to the outside. On my residential natural gas stove oven it is at the bottom of the panel disguised as a hard to see slot between the stove base and the panel. The hot combustion gases have to go somewhere. Since there are so little of them they are exited to the room. With a self-cleaning gas oven the reason the room gets so hot is because of these ovens get hotter when cleaning than when using them in normal mode. The normal gases going through the vent into the room and not the body of the stove. The same from the cleaning mode. Some manufacturers also recommend venting the room by opening a window, (to get rid of the hotter than normal gases really), to cool the room.

Refer to: http://www.karg.com/pdf/Presentations/Gas_Range_Overview_Nat_Wx_2001.pdf

Slide # 58 illustrates the vent from inside the oven.

Slide #80 illustrates the exterior location of the vents (disregard the wording on this picture)

Slide #66 shows the outlet of the vent being the black line below the clock and knob on the panel:

These clearly illustrate how residential natural gas stove ovens are vented to the room and don't need a chimney.

Good Luck, Old Salt

The following are the pictures associated with post #22, from

http://www.karg.com/pdf/Presentations/Gas_Range_Overview_Nat_Wx_2001.pdf

Slide #58, the vent from inside the oven.

Slide #80, The exterior location of the vents (disregard the wording on this picture)

Slide #66 shows the outlet of the vent being the black line below the clock and knob on the panel:

These clearly illustrate how residential natural gas stove ovens are vented to the room and don't need a chimney.

Good Luck, Old Salt

see http://cr4.globalspec.com/comment/1068812/Re-BREAD-OVEN-CHIMNEY

While it might not need a Chimney it still will need an exhaust fan. One way or the other.

Why then do about half of the newer houses use a fan hood that recycles the exhaust through a metal mesh and back out to the room. Total distance of travel is 6 inches. Not my personal preference but that is ok with the building codes. Stove chimney and/or fan vent to outside ARE NOT REQUIRED for residential. Good Luck, Old Salt

That I never understand. As if the smell goes away from being filtered through a metal mesh and it does not take care at all of exhaust gases.

If possible have the kitchen in a room without window. You sure there will be a gas oven in there at all?

The new installations are usually gas stoves with electrical oven.

But then it all depends on the building code. Do we know where OP is?

I don't think we know where OP is. He hasn't said and he's only been back once since starting this thread.

Had another thought on it - a gas hob with up to 6 burners uses more gas than an oven. In a residential setting the combustion products go straight into the kitchen without obvious problems. In that case why worry about the oven? In principle, if the room is very well sealed there could be oxygen depletion, but it doesn't seem to be an issue in practice, and no more so for the oven than the hob.

I still think it depends on the details of the specific installation, and local regulations (if any).

OK thanks. I think that confirms what I've been saying.

see http://cr4.globalspec.com/comment/1068812/Re-BREAD-OVEN-CHIMNEY

While it might not need a Chimney it still will need an exhaust fan. One way or the other.

That is why all gas appliances are required to have a vent hood. Very stringent rules in commercial applications, still needed in residential construction. -- JHF

No. But most commercial ovens do. At least an exhaust hood above them. More to pay attention to is the size of the oven and how much gas it will consume. And the size of room it will be placed. Un-vented or with out a chimney the oven may consume too much oxygen from the room.

Is it not possible the oven loses heat from the vent/chimney?

Yes it is, a vent (chimney) will VENT everything. Heat and burned gasses and flames!

My home oven does not have any kind of venting to the outside air and neither does the vent hood, it recirculates the air and filters it (poorly at best). These home type ovens burn clean enough to not have to vent to the outside.

Now for your idea?

1. What type of fuel? Propane or Natural Gas?
2. How many BTU's?
3. Size of oven?
4. Have you designed or even had a chance to perform a repair on a gas fired oven?
5. What are your qualifications in this field?

Good luck and be careful!

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While it's true most modern gas ovens burn clean and use little gas and therefore don't require "chimneys", commercial ovens and home built type ovens do...I might add that any stove or oven should have a hood that is exhausted to the outdoors....Gas water heaters do require 'chimneys' by code here in the US, as do gas furnaces and dryers....Years ago gas heaters were mostly unvented, I lived in a home with an unvented gas furnace years ago and can still remember getting headaches from it....The CO levels can build up in an enclosed space...If the room is well ventilated and the stove is for residential use, then you probably don't need an exhaust vent, but it's not a bad idea to have one....If the stove is for continuous commercial use, then be aware that CO levels is a real threat in an enclosed space, and probably required by code...or at least common sense....

It depends upon the installation. The building's insurers may require it depending on the type of building, its size, the rating of the oven and its location. If you intend installing it in the UK, then your insurer may require its installation and testing by a CORGI-registered gas fitter. I'd pick up the phone and make some calls, then I'm funny that way.

A chimney is not necessarily needed.

My backyard oven that was used for bread, pizza, roasts etc was built as a fire-box and once at temperature the fire was snuffed and the retained heat used to cook.

The wood entry door was also the escape path for the combustion gasses. It had no chimney to create "draw" and was very successful.

There are plans available for "backyard ovens" that have no chimney, specifically for the reason to reduce heat loss while cooking.

If this is going to be inside a house/building, then a chimney is essential to get the combustion gasses away from the people or else really bad things can happen.

You are the designer, you MUST know such things, not ask here.

If we collaborated and all said "NO", and someone died of CO poisoning, would you come back and blame us?

Yes. -- JHF