pompeii oven construction began today

[david s]

The floor insulation is something that has obviously changed. The plans when I build this oven called for a concrete hearth directly beneath the floor bricks, with pcrete under that. If you look through my thread you'll see where I suggested flipping that, with the floor bricks being the only thermal mass in the bottom. Glad to see that is the norm now.

It all depends on what you want your oven to do. For a bread oven a very thick dense floor is good because high temperature wicks away into the cooler part of the floor. This results in more heat storage and a reduced tendency to burn the bottoms of bread loaves. You can do multiple loads of bread without the temp dropping off so fast. The downside is that it is really difficult to keep the heat high enough in the floor for continuous pizza cooking and the oven takes longer to heat up initially.

[paulages]

2. What do you consider slow heat-up? 2-3 hours for a white dome is not uncommon. Insulation has changed over ten years, recent rule of thumb is that CaSi board or blanket is twice as efficient as P or Vcrete. So most recently, a min of 2" CaSi is recommended under the floor with 3-4" better. This mean 4" min P or Vcrete or 6-8" optimal under the fire brick floor. Maybe the 2.75" of Pcrete (1.375" equiv. CaSi) under the old oven was not enough floor insulation so the concrete base acted as a heat sink which I guess in a sense too much thermal mass. My oven has 3.5" of CaSi and FoamGlas under the 3" thick firebrick floor, 3" of ceramic blanket and 3" of Pcete on the dome. IMHO, insulation is a key component to a high efficient oven. The new generation ovens are getting 4-5 days of workable cooking heat. One recent oven builder is saying they are getting 10 days.

The floor insulation is something that has obviously changed. The plans when I build this oven called for a concrete hearth directly beneath the floor bricks, with pcrete under that. If you look through my thread you'll see where I suggested flipping that, with the floor bricks being the only thermal mass in the bottom. Glad to see that is the norm now.

[RandyJ]

I would also say that it is pretty much a stick and move process. And if you have the mortar just right and the bricks properly wet you can make it a little farther up the dome. I was either lucky or dumb but I did mine like that all the way to the top. As soon as I had 3 bricks in it seamed to hold ok.

As for insulation the Moro the better. I used 4" of ceramic board from McGills warehouse under the oven. Then I did 3" of ceramic blanket over the top of the dome and filled the enclosure with 36 cf of vermiculite over the top of the insulation. I also did heat breaks at the dome to vent ant floor to vent. AlSo I put paver stones under everything that acts as drainage if it should get wet.

I am seeing temps around 700F floor and 750F dome the next day the next day will be mid 600F range somewhere. With the insulating door in place it will take up to 10 days to cool to under 100F I normally do a batch of bread on day 2 or 3 but nothing past that yet. Note this is with outdoor temps below freezing and sometimes well below 0. I am very happy with how it turned out.

Randy

[UtahBeehiver]

Maybe 10 days is a stretch for "cooking" heat but here is the link of claim to fame by Randy J.

http://www.fornobravo.com/community/...?r=5539921&p=2

[oasiscdm]

Hey Russell who is getting 10 days?. Best I have done was 5 days having heated it to 550c after a pizza cook. Keep it going until I get outside brick temp of 400 and inside of 480 or more, take fire out seal and it equalises at 440, from there drops about 40 - 50c deg per day. A little faster if the door is taken off to much. I tend not to use it if it drops below 100c. would love to get next one to maintain for 7 days then it would heat up quicker for pizza on Friday nights.

My next oven I am going to double the insulation I used on this one. around and under.

[UtahBeehiver]

Here a few comments.

1. I would venture to say at least 2/3s of the dome you can move the IT after you set the brick assuming your mortar is right consistency. The upper third of the dome, where gravity takes over goes a little slower, I had to set the brick with the IT for angle and orientation then placed a stick under it and moved to the next one. Slower but not as bad as one thinks. Somebody did a dual arm, not sure how it work out but it has been tried. If you can make a support ring, go for it. I guess it would be similar to jack and a plywood panel or a exercise ball. I tried the plywood method and did not like the alignment results on the inside.

2. What do you consider slow heat-up? 2-3 hours for a white dome is not uncommon. Insulation has changed over ten years, recent rule of thumb is that CaSi board or blanket is twice as efficient as P or Vcrete. So most recently, a min of 2" CaSi is recommended under the floor with 3-4" better. This mean 4" min P or Vcrete or 6-8" optimal under the fire brick floor. Maybe the 2.75" of Pcrete (1.375" equiv. CaSi) under the old oven was not enough floor insulation so the concrete base acted as a heat sink which I guess in a sense too much thermal mass. My oven has 3.5" of CaSi and FoamGlas under the 3" thick firebrick floor, 3" of ceramic blanket and 3" of Pcete on the dome. IMHO, insulation is a key component to a high efficient oven. The new generation ovens are getting 4-5 days of workable cooking heat. One recent oven builder is saying they are getting 10 days.

3. Deejayoh has a spread sheet to help with calculating number of bricks based on size of dome. That would get you a rough number on brick weight, too many variable on the other materials, enclosed or not, finish materials, type of insulation, SS chimney or masonry, etc. to be able to quantify a weight of an oven.

[paulages]

Ok, new house, new oven! I moved a year ago and hauled all of my bricks with me. After poring through the past 10 years of builds since I built this one, I see you guys have improved a few things! I think rather than re-build this one, I'll build a new one salvaging the bricks from the first. I still need to design the deck it will sit above, so I won't start for a bit. I'll start a new thread once I do, and I'm sure I'll have many questions.

I'll start with a few:

1) I think I'll build and use an indispensable tool this time instead of a Styrofoam form like I did before. It worked fine and I don't care so much how it looks on the inside, but I want absolute heat performance. I think with the bricks fit tighter it will reflect heat better than before. That said, how are guys using the tool as I've seen it done here without having to wait for each brick to set up on the upper courses? It seems inefficient to set one, wait for it to support itself, and then move on. Thus, I'm thinking of making a support ring for each course rather than a single arm. instead of one adjustable arm, it would be three arms with an adjustable support loop on top. then the whole course could be set at once and the tool removed once the course it self supporting. Am I missing anything here?

2) One of my biggest complaints was slow heat-up time and too much heat mass in the floor, as you'll see if you read through my thread. I built according the the plans at the time (with the exception of a lower dome, tapered bricks for the top three courses, an integrated arch doorway rather than an angle-iron lintel, and castable insulation rather than a blanket. The hearth was built with 2.75" of pearlcrete beneath 2.75" of regular concrete, which I believe created too much thermal mass in the floor. In retrospect I would do it the reverse, or at least have an insulated pad that the floor actually sits on so that the heat stays only in the firebrick floor. Not good for building thermal mass for bread baking later, but pizza is my priority, and temps dropping below 750?F aren't good. This was discussed some then in this thread and others, but again...that was 10 years ago. Is there a consensus now as to the right amount of thermal mass?

3) Back then there were weight guesstimates for the dome section. Has anyone done a somewhat accurate measurement there? I need to elevate mine quite a bit, and I need an idea of the load I'll be putting on footings and posts.

Can't wait to get started again!

[paulages]

Re: pompeii oven construction began today

Wait until you have to move and leave that behind. There will be tears aplenty then.

[QUOTE=Gulf;175548]Staaaaay!....................... single?....................... .[/QUOTE



Hahaha...too late for that one! Happily married.

[Gulf]

Re: pompeii oven construction began today

Well Jim, that day came.

When I built this oven, I always had in mind that I could forklift the hearth right off of the stand. I arranged with the ex to come pick the oven up, and reserved a flatbed and boom lift to move my baby to it's new house. Kim and I were not on good terms, so she was not there when I arrived. Her camper was however, and was completely blocking access. This was a one-shot to get it kind of deal, so I had to break out the sledges.

I have photos of the carnage, but I'm in Europe at the moment. Loose perlite everywhere, smashed housing walls...it was ugly. I had to be quick though, and take the valuable components.

I now have a numbered pile of fire brick and chimney pipe sitting in my new garage. I think I'll be rebuilding it on a trailer this time.

Sooooo! What have you all learned in the last 9 years that can help me make this one better?

Staaaaay!....................... single?....................... .

[paulages]

Re: pompeii oven construction began today

Wait until you have to move and leave that behind. There will be tears aplenty then.

Well Jim, that day came.

When I built this oven, I always had in mind that I could forklift the hearth right off of the stand. I arranged with the ex to come pick the oven up, and reserved a flatbed and boom lift to move my baby to it's new house. Kim and I were not on good terms, so she was not there when I arrived. Her camper was however, and was completely blocking access. This was a one-shot to get it kind of deal, so I had to break out the sledges.

I have photos of the carnage, but I'm in Europe at the moment. Loose perlite everywhere, smashed housing walls...it was ugly. I had to be quick though, and take the valuable components.

I now have a numbered pile of fire brick and chimney pipe sitting in my new garage. I think I'll be rebuilding it on a trailer this time.

Sooooo! What have you all learned in the last 9 years that can help me make this one better?

[Laurentius]

Re: pompeii oven construction began today

I apologize, terrible, tasteless, joke.

[cobblerdave]

Re: pompeii oven construction began today

Gudday
Read through your post ,very interesting. How are you getting your oven back ?
Brought back the property or fork lift the oven off its stand?
Regards dave

[paulages]

Re: pompeii oven construction began today

Haven't been here for a while, and haven't used my oven either, but today I finally get to go get it back! In one way or another...

[paulages]

Re: pompeii oven construction began today

Been a while, guys... I lost the house in the split with the ex, and may need to build a new oven. If so, it'll be better than ever! I'm hoping to take the old one though, as the slip plane between the hearth and the base means I could possibly forklift the entire thing heart-up...

[james]

Re: pompeii oven construction began today

Hey all,

I'm back in the saddle -- and I am pretty sure Paul is still available and using his oven often. I will contact him and see what we can do to host all of his photos here. As David says, Paul was early and did a wonderful job -- both the oven and pizza dough. :-)

How are you doing Nick? Have you fired the beast yet?

James