First course

[benguilford]

Re: First course

I have been trying to track down your build post for a while now, that is looking like a brilliant oven! I have attached a sketch to illustrate what everyone here is talking about - you really want to 'cocoon' the whole oven in good insulation, it makes a HUGE difference to the performance of your oven as a whole.

Also, the refractory slab that you are going to pour, this is basically just a dry mixed refractory brick - when you pour this slab it will have very similar properties to the refractory brick floor (dense, fairly thermally conductive) so it will act as additional thermal mass under the floor. Is this what you were intending? 4" of additional thermal mass is significant, it will take a lot longer to heat up, but will also hold its heat for a long time (providing it's well insulated ) Unless I have the wrong end of the stick entirely and you've got your hands on a premixed insulating castable...

[shuboyje]

Re: First course

Although I agree with what everyone else is saying here, the important question I haven't seen asked here is what were you trying to achieve with your alternative design? It's pretty complex so I have to assume there was a certain goal in mind.

Your work looks really nice, take a step back and get this part right and you should end up with a great oven.

[Omaharosario]

Re: First course

First I wanted to start by saying Thank You!
If the soldier course is floating on insulation board, does your soldier course get a good enough bond to the Refractory Castable Layer and each other to be structurally sound? Also I have already poured the Refractory Castable Layer. I have been talking with a gentlemen who has been involved with a couple of commercial oven in the area and this is where a lot of my ideas are coming from. Hope I did not go to far off the path, But I know the help from everyone will help me get there. Thanks again!!

[benguilford]

Re: First course

From your description the refractory castable layer is only bonded to the inside face of the solider course, and it really doesn't need to be bonded to the soldier course at all for your oven to be structurally sound - most of the ovens here on this forum cut the floor to fit inside the soldier course, which means the soldier course is self-supporting.

Do you have a layer of insulation under the refractory castable slab? If so, you could just lay your firebrick floor directly onto your refractory slab (with a thin layer of fireclay to level the floor bricks).

A sketch would help (I think I must be one of those darn 'visual learners' that my English teacher wife talks about)

[shuboyje]

Re: First course

I think the refractory castable layer is what has us all thrown off. As you have it now it is doing little to nothing other then mayber stealing heat away from the oven and keeping it there. In commercial bread ovens they generally do something to increase the mass in the floor to retain heat for many loads of bread after one firing. The way you have this constructed won't even do that because it has insulation above and bellow. It's only contact to anything conductive is on the sides.

As for bonding to the castable layer, that's a moot point IMHO. The soldier and the castable will expand at different rates and the bond will probably be broken by themal expansion anyway.

[Mike D]

Re: First course

I know this sounds lame, but I would pull off what you have now and start it over again. Your not that far into the dome. And the amount of time you have already put into it (the stand an foundation), and the amount of time you have left would be a shame if you were to build an oven that you knew to be flawed.
-The insulation under all the bricks serves as a heat break. You soldiers will be moving your heat into your slab not back up into the dome.

Mike

[jcsites]

Re: First course

I admire your views and ideas about building ovens. You're a great help. Thanks for the info. Good job.

[benguilford]

Re: First course

So what did you decide to do in the end Omaharosario?

[Omaharosario]

Re: First course

So what did you decide to do in the end Omaharosario?

I think we are going to cut out 2" of the fire brick soldier course and the stuff all the insulation we can fit in and around the fire brick soldier course. then all will be floating on insulation. does this sound like a comparable change to fix things?

[Les]

Re: First course

Oma,

I may have jumped the gun on my first post (using a smart phone, not much detail with the pic's) You have 50% of the soldier course above the floor. It's hard to believe that the brick can wick that much heat to ruin your build. It's does conduct heat but it's not like it's a solid bar of copper. It's not an ideal situation but may not be a disaster either. JMT

Les...

[christo]

Re: First course

I tend to think like Les (scary, huh ) - 50% is better than 100% and most of us are just trying to make a few pizzas in the evening and don't care too much about retaining heat for baking bread the next morning.

If you fit into this category - I think you'll burn a bit more wood but you'll be fine with the changes you are making.

Can't wait to see more pics!!

Christo

[Neil2]

Re: First course

"I think we are going to cut out 2" of the fire brick soldier course and the stuff all the insulation we can fit in"

Just pull them up and relay them. This might tale less time and trouble.

[Omaharosario]

Re: First course

"I think we are going to cut out 2" of the fire brick soldier course and the stuff all the insulation we can fit in"

Just pull them up and relay them. This might tale less time and trouble.

I am a little worried about not being able to use the FB after we pull them off. I am thinking they are going to be all gumed up with mortar?

[GianniFocaccia]

Re: First course

When I pulled my soldiers apart most of the mortar came off easily. The stubborn pieces were easily removed with an angle grinder.