Pizza History in the Hammer Continues

[MarkJerling]

david,

I've never had a fire so intense that flames have gone up the chimney. Heck, I don't recall ever see flames rolling out of the dome arch. Across the ceiling of the dome, yes, but coming out the arch, never.
I've shot all sorts of temps over the years, and have never come close to seeing temps in the throat high enough where the silicon could suffer degradation. Next time I fire it up I'll try to remember to take and post some temps.

Ours have the flames roll out of the dome and up into the chimney throat when I have a decent (olive wood) fire going, most recently last night. Of course, with my curved (firebrick) flue, I doubt the flames get all the way to the start of the metal flue. It's quite pretty watching the flames curve through the door opening and up into the flue gather. I should shoot a short video when I fire it again. As a bonus, not only the dome burns white, but the top of the door arch too.

[mongota]

Another problem can be the type of fixings used. I don’t trust the longevity of plated or galvanised fixings and would only trust stainless ones.

Fully agree there.
For the amount of time, thought, money, love, and effort put in to these builds? I'd encourage everyone to spend an extra $15 to get SS over galvanized.

[david s]

Ok, maybe it will work then. My wife fired the oven once(usually my job) and overcharged the chamber, which caused too much flame in the gallery. This destroyed the seal between the pipe and the terracotta weather cap. It was no big deal because it was easy to redo being exposed from the outside, but had it been at the base of the pipe which is not accessible, being covered with vermicrete and render layers it would not be an easy fix. It is one of the reasons I don’t use an anchor plate. Another problem can be the type of fixings used. I don’t trust the longevity of plated or galvanised fixings and would only trust stainless ones.

[mongota]

david,

I've never had a fire so intense that flames have gone up the chimney. Heck, I don't recall ever see flames rolling out of the dome arch. Across the ceiling of the dome, yes, but coming out the arch, never.
I've shot all sorts of temps over the years, and have never come close to seeing temps in the throat high enough where the silicon could suffer degradation. Next time I fire it up I'll try to remember to take and post some temps.

[david s]

What kind of fixings are in the holes?
From my experience the High temp silicon at that point is quite vulnerable. In my design I use it higher up where it deals between the flue pipe and a terrscotta rain cap. If flames are allowed up the flue pipe it will destroy the silicon. Under normal operation where a little flame is licking out the oven door and into the flue gallery it’s ok, but if the oven chamber is overloaded with fuel and flames are allowed up the chimney, it will destroy the silicon. Yours could be different, try it and see. The highest rated silicon I can find is Permatex Ultra Copper which I use.

[mongota]

Good points. I drilled slightly over-sized holes and bedded the anchor plate to the brick with beads of RTV silicone. If the plate thermally expands and contracts a bit, the RTV can absorb that movement. If the anchor bolts deflect any with of that thermal movement, the oversized upper part of the holes can allow for that movement without excessively stressing the brick. Regardless, no cracks in the bricks or in the mortar joints.

I ran some numbers way back when...for my 8"D chimney, the anchor plate I used was about 12" square, the anchor holes were about 10" apart. So from the centerline of the plate, the holes were roughly 5" from centerline. Using a roughly 700F delta-T, I figured the plate would expand just over 1/20th of an inch in each direction from center. Going worst case, with one corner anchor held tight and the plate as a whole expanding only AWAY from that single anchor point (10" instead of 5"), and with a 900F Delta-T instead of 700F, the expected expansion was about 1/8th of an inch.

My oven had held up fine. No anchor plate issues.

Plan for the worst, hope for the best.

[Baza]

P3 Stoaker - WOW, THAT'S HOT!!!
Wondering if there aren't limitations on the use of your mortar under such conditions!? WOW!

Yep! Bought and got the Duravent Chimney and it is waiting for Spring ... like me and my withdrawal!! Well noted!
Looking at the assembly - the base plate and how you put it into your chimney system is the main "challenge" - there are lots of incarnations of that approach here - Check out Dino Pizza's version of crafting a mortared down base plate; Utahbeehiver and Mongota have brick assemblies they created to level a space over the arch so the plate can be screwed down (lots of talk on the forum re: being wary of this given the propensity for the brick to crack when screwing in to them).

The chimney then fits OVER the lip sticking up from the baseplate - a turn and it snaps in place - very solid and snug.
The only concern for moisture getting past the plate will come from how you seal the space around it (and the above builders all have their own unique approaches to this). And, of course, the top of the chimney - but everyone puts some kind of cap on it. Any moisture getting through after these considerations is nominal at best.

Expansion is a good question on it too - some have drilled holes slightly larger and let the enclosure of their oven provide the stability that the larger holes may complicate.
Those who have mortared or tight screwed their plates down claim to not have expansion issues (well, some cracking) that compromise either the integrity of the structure or the cook.

Yep - plenty of time to research what is considered the most complicated aspect of the build: vent and chimney!
But what plonker on this site who started to build a wood-fired oven from scratch - digging holes, throwing concrete and brick around - isn't up for a bit of challenge!!??

All the best Greg!
Stay cool!
Barry

[P3 Stoaker]

G'day Barry,
How goes things, are you suffering from with-drawl symptoms yet?
Things have slowed a little here at the moment, forecast today and tomorrow 44 deg (111 F). It was 36 (97 F) by 9am this morning.
I've been searching lots on flue's and base plates. Did you order a 'Durachimney 2' product?
Are you aware if the flue sits 'in' or 'over' the base plate? My thoughts are that if it fits 'inside' then water (rain) will also go inside and and up on the oven floor??
Additionally after searching I didn't find a lot on the expansion difference between the base plate and brick-work it will be mounted to? I wonder if simply having bigger mount plate holes is the answer? Seems too simple to me.
Plenty of time for your planning now things are all covered up.
Take care.
Greg

[Baza]

P3 Stoaker - and a G'day to you too!
Great to read that you are back at it - but WOW - that is HOT! You in Northern Oz? Seems you don't need an oven with those temps! Definitely looking forward to your build pics! It is interesting to watch builds and commentary change as the excitement of beginning makes way for the challenges of closing! The steeper parts and the clever and innovative ways to accomplish the dome closure are fantastic! Like you said, Greg, the informative answers here get you through!

Despite the encouragements to keep going under a tent (I actually have been building the whole thing under a tent) ... and I DO appreciate them! - I closed up because of work and other pressures getting in the way (and only JUST picked up my chimney assembly yesterday!) ... so shut it down until, likely, April - pending weather. Bummed - but ok with it. Seemed a bit of a cruel joke by nature that I tarped and lowered the tent on a cold 4 degree Celsius day ... and the for the next two week saw temps in the teens! (Celsius!) - I could have kept going! Damn!

Oh well - something to look forward to in the Spring!!
In the meantime - I will live vacariously through yours and others' builds!!

Good luck mate!
Barry

[P3 Stoaker]

G'day Barry,
Impressive progress, your build looks great. How long until the weather will allow you to continue? I've completed my work trip and 2 weeks hotel isolation post overseas travel and just back into it yesterday. I'm about 4 rows from the plug and realising just how steep it's getting, as I'm sure you experienced, what just worked for the last row isn't so good any more. I'm starting to think more about the entry and have enjoyed reading your questions, and of course the informative answers.
I have the opposite problem here in that it's very hot, often 38 deg plus (100 deg F) and will soon cycle probably weekly past 42-43 deg c ( pushing 110 F). So it's a case of pick the cooler days and start early, especially when nights are cool , 20 deg c(70 F). I'll get some picks up soon.
Regards
Greg

[MarkJerling]

ARG ... I know ... but the weather is colder and unpredictable (look at me tell you that living in UK!).
With all that is left to do - hitting it fresh with time to finish the vent landing, chimney (not in yet), blanket, enclosure, curing ... I'll just wait till the Spring and have a Summer of Pizza in 2021!!
Appreciate the encouragement to keep it going, though!

Will certainly be jealously watching the wonderous next steps of the builds you all have!!

I bought a big gazebo and erected that over the top of my build. Allowed me to keep going right through winter! That way I was done by spring.

[Baza]

Barry, you can't leave it now.
I feel like me, you and John all started our builds together and all build the same size...build a temporary shelter and continue on our journey.

ARG ... I know ... but the weather is colder and unpredictable (look at me tell you that living in UK!).
With all that is left to do - hitting it fresh with time to finish the vent landing, chimney (not in yet), blanket, enclosure, curing ... I'll just wait till the Spring and have a Summer of Pizza in 2021!!
Appreciate the encouragement to keep it going, though!

Will certainly be jealously watching the wonderous next steps of the builds you all have!!

[Neil.B]

Barry, you can't leave it now.
I feel like me, you and John all started our builds together and all build the same size...build a temporary shelter and continue on our journey.

[Baza]

Hey John ... thanks for the support and kind words - like saying farewell to my kid going off to school ... "see you in the Spring my love!"

Ope-dog - wow! AWESOME to read that you are moving forward. I just know the weekends and weather will be too much here. It's ok - something to look forward to!
As for YOU - really exciting to read that you are getting your brick and fireclay (I guess you are doing the home-brew from here - I hear it is excellent!). That first cut into brick is a special moment - and all the ones in-between towards that plug at the end ... excited to know your canopy and enthusiasm will not allow your spirits to be dampened by NW weather!! Good on you and looking forward to following your build!

As for your question: I cut the Cal-Si board with a simple jigsaw! Went through it like butter!
But BE SURE TO WEAR A MASK (not that we need such encouragement these days) ... it has some nasty stuff in it and you don't want to break this as it produces particles in the cut!

Good luck mate!
Barry

[CapePizza]

Good haul on the fire wood! Sorry to hear about the "hibernating" issue.... was looking forward to seeing your progress.... but will see it when we all emerge out from winter. TakeCare......