I'm getting closer to my Dome!

[Aegis]

Re: I'm getting closer to my Dome!

Where, might I ask, did you find your thermocouples? I would love to plan on using as many as you, but they are so darn expensive. Are you using the thermocouples sold by FB?
Looking forward to seeing the results and progress of your build, as well as how the foamglass shapes up!!
Happy Bricklaying!
-Simon

Hi Simon, I purchased the thermocouples and hook ups through Omega.com.
Meter # DP7005 Price $83.00 (I would recommend DP7002 it is centigrade and runs on 115Vac-centigrade expands the top temp. You can read)
Thermocouple 5TC-GG-K-20_72 Price for 5 is $49.00
Extension Wire PR-K-24-SLE-50 Price is $32.00 for fifty feet

As for the oven build, it is still awaiting the finishing of the upper patio arae around the hot tub before I get back to full time oven. Hopefully by May 1st or sooner! Darn family functions get in the way along with a wet spring in N.E.
Hope this helps
John

[SableSprings]

Re: I'm getting closer to my Dome!

Hi Mike,
I will definitely use the percrete mix, once I find perlite. Great photos!!!!!!!!!!!! THANKS!
John

I used two sources for perlite. One was the local Cement Block & Brick company. It had good sized bags (4 cu ft - 25#) for under $13 each. It was marked as masonry fill and consequently has a smaller average particle size with a light, silicone coating. I only noticed that silicone coating during the initial mix with cement, the cement powder washed off the perlite when I added water. (Remember to use a breathing mask, as when you are working with both the perlite and cement they both produce a lot of fine dust.) It quickly mixed back together and cured with all the strength I'd hoped for, so I didn't consider it a problem.

The other source was my local gardening supply. Their 25# bags were more expensive (at just under $20/bag). The particle size on the gardening stuff was probably 2-3 times larger and it doesn't have the coating. The cement did not wash off the perlite as easily and it mixed up easily (and seems to be equal to the smaller size perlite in cured strength). I mixed a wheel barrow full at a time, using a bucket to measure out 5:1 volumes of the perlite and cement. (Use a breathing mask!) Go slow on the water addition and don't make it too dry...I thought of it as along the lines of cookie dough. You've got to give it enough water to hydrate the cement fully.

[Aegis]

Re: I'm getting closer to my Dome!

Mike, Thanks for the info and Helpful tips! I will attempt to incorporate them into the hearth for leveling. I am finishing up some back staircase from my deck to the patio/oven area. As soon as that is completed I will start on the oven.

I have a thought on heat breaking the chimney/flue area - Please everyone comment on the feasibility of this idea. I thought at the point of arch to flue transition, to install a 4" piece of foamglas for a thermal break between the arch and the chimney brick ascending. Can foamglas take this amount of heat? Otherwise I will go the insulating brick route like brikie did with his build.
Thanks
John

[Aegis]

Re: I'm getting closer to my Dome!

I guess no thoughts on the foamglas heat break?????
Well I will be starting work on the hearth tomorrow!!!!!! Yippie!!!!!!!!! First I will draw the outline of the hearth onto the bricks from my template. Number and cut the bricks to allow the walls to be on the outside of the hearth bricks. Then I will be laying a sand/fireclay base to allow leveling of the foamglas. Then on the foamglas another layer of sand/fireclay to allow leveling of the hearth bricks! I'm shooting for the hearth bricks cut and repositioned for the oven as the immediate goal. I'll post some pics as I go along.....

[dmun]

Re: I'm getting closer to my Dome!

I guess no thoughts on the foamglas heat break?????

I haven't worked with it myself, but I don't think it's up to direct flame/flue gas contact.

[Aegis]

Re: I'm getting closer to my Dome!

I haven't worked with it myself, but I don't think it's up to direct flame/flue gas contact.

Thanks for the input, it sounds like you are correct given the following:

I looked up the spec sheet and it gives a maximum service temperature of +900 degrees F or 480 degrees C.
Since I have absolutely no fireplace/chimney experience, I guess my question is: does anyone know how hot the chimney bricks get? If it is over 900 degrees F then It is insulating firebrick for sure!
dmun, are you saying it gets that hot? It sounds like it could!
Thanks in advance
John

[brickie in oz]

Re: I'm getting closer to my Dome!

does anyone know how hot the chimney bricks get?

Ive clocked the flue gasses through the slot for my damper in the chimney and they get to over 600c.

The bricks dont get this hot though, but I would imagine closer to the oven exit they may.

[Aegis]

Re: I'm getting closer to my Dome!

Ive clocked the flue gasses through the slot for my damper in the chimney and they get to over 600c.

The bricks dont get this hot though, but I would imagine closer to the oven exit they may.

OH NO!!!!!!!! Brikie, you sparked a bad thought! Brick temperature!!!!!!!!
Hearth Brick temperature for sure!!!!!!!!!!!!!!!!! If the temperature of the flue bricks exceed the foamglas working temp of 900 degrees F then the hearth bricks under the fire will also???? so much for putting the hearth bricks on the foamglas.... Does anyone have their hearth bricks directly on the foamglas??? Is it ok???? I am going to be doing my hearth today, or so I thought! Help!!!!!!!!
Thanks in Advance
John

[Aegis]

Re: I'm getting closer to my Dome!

Here are a couple of pics so far of the hearth layout. Hope it isn't too bad, and I especially hope putting the hearth bricks on the foamglas is ok!

[SableSprings]

Re: I'm getting closer to my Dome!

.... Then I will be laying a sand/fireclay base to allow leveling of the foamglas. Then on the foamglas another layer of sand/fireclay to allow leveling of the hearth bricks! .....

It's hard for me to imagine that if you are putting 1"-2" of builders sand/fireclay on top of the foamglas (to level the hearth bricks) that you'll ever bring that insulating foamglas board up to 900?F with your normal use of the oven. Wing & Scott (The Bread Builders book) have some deep probe figures on heat loading that are pertinent here. The thermographs showed two oven's temp profiles (pgs 204-205) at various depths into the firebrick. At 2" & 3" down into the brick, max temps ranged between 550? to 825?. The high (825? at 2" deep) in a commercial bread oven had 1" temps that stayed above 900? for 6 hrs during their firing and deep masonry heat loading cycle.

This data tells me that for "our home use" a 3-4 hr firing for "casual pizza" just isn't going to bring that base insulating board to its max temps...especially with a layer of leveling sand on top. Relax...

[Aegis]

Re: I'm getting closer to my Dome!

This data tells me that for "our home use" a 3-4 hr firing for "casual pizza" just isn't going to bring that base insulating board to its max temps...especially with a layer of leveling sand on top. Relax...

Thanks Mike!!!!!!!!!! I'll take your advice and open a bottle of Merlot and now I can relax! Again thanks for the info!
John

[Aegis]

Re: I'm getting closer to my Dome!

Thanks Doug for the info! I wish there was a sticky thread with this kind of real data so we can use the best materials for our particular application.

Again THANKS
John

[Aegis]

Re: I'm getting closer to my Dome!

Here are some progress or not so progressive pictures of the build. Having a little trouble with the reveal/arch/hearth interface. I may have it under control and just might lay the inner arch foundation on top of some hearth bricks. I'll dry stack my solution when I get some more time from work. Till then here is what I have so far....

[Mike D]

Re: I'm getting closer to my Dome!

Looks super clean, keep it going.

Mike

[Aegis]

Re: I'm getting closer to my Dome!

Looks super clean, keep it going.

Mike

Thanks Mike for the compliment, although I hope you can say that when the mud starts to fly! No mud = no mess!