Steam Vent Idea - comments please

[cnegrelli]

Where were the Breather Vent Caps sourced from? I'm having trouble finding these and thought this would be as good a place as any to post this info.
The other great idea on this is david s breathable flue design, but seems to require some custom work with pottery materials. I'm thinking of casting something like that with the castable refractory - if David has any comment on that. It looks like two pieces with the top being essentially a collar to divert rain and the bottom piece used to mate the chimney to the flue. There must be some venting between these to allow the steam to escape, which may just be a function of not having an airtight fit?

[Man Food]

Hi Tommo

Yes I could see some whisks of vapour coming out which was a good sign it was working.

[tommo21]

Great idea and i will utilize one too i think.
Was steam visible during curing?

[Man Food]

Fired the oven to 400c for the first time yesterday and the steam vent worked a treat! No cracks so far either....

[Gulf]

Just uncap it when you do your initial drying and at any time you fire the oven after it has been out of use for some time, or you feel that the oven has taken on a lot of moisture. You should be able cap it securly most of the time. A simple gooseneck fitting will allow you to vent even while it is raining. There are lots of ways to do this.

[Man Food]

that breather vent cap idea of Gulfs is great, I missed that! I will need to manually open mine or leave it slightly unscrewed to allow any steam out. Hey ho...

[UtahBeehiver]

I used a breather vent cap, which was Gulf's idea.

[cnegrelli]

What was the vent that others used that automatically would open under pressure?

[Man Food]

I installed the steam vent tonight - see the attached pics. I hope it works!

[Man Food]

Thanks Gulf, that makes sense - I will try to fit it over the next couple of days and post a pic of it in place

[Gulf]

Imo it will work. However, I would skip the cutoff blades. Same idea to lock it between the threads. But, get a piece of mesh cut in a circle. I used 1/4" hardware cloth. You only need one to embed it securely in the render. Also, you can use pvc to save $$$ .

[Man Food]

Some more info - This vent idea is not designed to go through the ovens brick dome into the actual oven, but rather simply vent between the render coat and the C/f insulation layer - will this work to disperse any steam created and help prevent the dome cracking? Lots of self doubt here....

[Man Food]

Hi I'm a Wood Oven and forum virgin and have read this thread with interest. Currently I am building a 110cm diameter oven in my back garden - Big learning curve!

I have also thought about the build up of steam in my oven as it will never be completely waterproof, so I have come up with a simple vent made from some 15mm brass plumbing fittings and two 125mm grinder discs. The idea is to embed the whole fitting in the top of the oven forming a sandwich with the cutting discs to make it secure.

Here are are a couple of photos to show you what I am thinking of doing - what do you more experienced oven builders think? Is this a stupid waste of time?

[david s]

Yes, by press moulding them. The trick is for the lower one to have some clearance from the flue pipe so it can expand without damaging anything, while the upper one has some high temp siliconbetween it and the pipe.Steam can escape between the two caps because there's always some gap with the less than perfect fit.

[cnegrelli]

This is my solution. I make two terra cotta collars that go around the flue pipe. Moisture does not go up the flue but beside and outside the pipe.The bottom one has a larger internal diameter than the flue pipe so moisture in the insulation layer can find its way out. The top one has a hole a few mm larger than the flue pipe and that gap is filed with high temperature silicon. The moisture finds its way out of the porous terracotta and the less than perfect gap between the two collars. I can't see that the vent has to be placed at the top of the dome as steam should find its way out wherever it is, although the top gets hottest fastest so it should probably go in at least the top half of the dome.There is a fair bit of mucking around fabricating with clay because of shrinkage calculations on drying and firing etc. but for a one off something fabricated in stainless would work as well. This system also prevents the render/stucco from cracking around the expanding flue pipe, which is often also a problem area for water entry.

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Are these terra cotta collars of your own making?