Steam Vent Idea - comments please

[david s]

I don’t tie down the blanket with chicken wire because it’s too time consuming and the vermicrete layer applied over it holds it in place. Placing a conductive material in an insulation layer is also counterproductive.

[snipe97]

Thanks David S. Been doing a lot of reading and figuring out the best approach. Planning a stucco finish so was thinking insulation -> chicken wire -> stucco (i.e. no vermicrete). Just trying to figrue wgat's best if I go the stucco route.

[fox]

You just have to be carful not to pile on to much cement in one go as this will squash down the insulation.
Best to apply several very thin coats of cement mix until you have a firm base to lay a decent coat, using a vermiculite coat is good option as it is much lighter but ... is not as quick or easy to apply.

[skulessa]

Hi All,

The idea of a vent for steam makes a lot of sense to me. I don't think it matters where on the dome the vent is placed and I don't think it needs to be at the top. If the moisture has turned to steam it will be under pressure and will exit through the vent no matter where the vent is placed.

I was thinking of creating a hole that communicates from the insulation layer into the flue of the chimney. It would always be open. Is this a reasonable idea or a bad one? If this is an okay way to go I'd rather do this than embed a metal pipe through the render layer. I'm assuming the pipe heats up?

Thank you for the advice.

[david s]

Yes you could certainly allow it to vent into the base of the flue pipe. Just drill a few holes in the appropriate position below where the stucco will meet the pipe. My solution is a little different in that moisture escapes between two terra cotta collars that support and seal around the pipe.
Some holes through the supporting slab also provide an escape for moisture in the underfloor insulation and do a great job keeping it dry.

[Mark1986]

Hi, I read this thread and I want to add the a steam vent to my dome. I don't have any idea on how much pressure 1 bar is, but would a configurable vent cap with a rating between 1 and 4 bar, open when I use it to vent the insulation layer? Or is there no pressure build up like that? Thanks!

[CapePizza]

If you do a search for breather caps on the forum you'll find plenty of info. I'll share what I did. We live in a very moist environment so I felt a breather cap would make sense for my build. I bought a hydraulic breather cap at Napa. They are not expensive. Mine was $13. Another member suggested this mounting method, as shown in one of the attached photos. I mounted it on top of my oven, resting the PVC connecting pipe right on top of the insulation. The PVC connector is held to the wire mesh with electrical locking nuts. I had used metal lathe to hold the insulation in place which also provided a good surface to embed the perlcrete layer. See attached.

[mongota]

The vent caps do work. I use a black iron pipe nipple. The last time I fired my oven up after several weeks of inactivity, a few hours in to the burn I uncapped it and the inside of the pipe was wet with condensation and the cap had a little puddle of condensate in it. I left the cap off for the remainder of the fire.