First Post - A Few Questions

[mpholland]

I've been reading through many of the threads in the Pompeii Oven Construction section and the information has been invaluable. I am ready to build and think that I have a reasonable understanding of what's required. A few questions before I take the plunge:

1. I live in NW South Carolina and have had trouble locating a local source for firebrick. I was able to find one size of Whitacre-Greer bricks (mentioned in the forum) that are buff color, 2.125" X 4" X 9" which weigh 6.25#. I am assuming that these are the low duty (27.6% alumina) firebricks that WG shows on their website. If I do the math, the density looks about right vs the 2.5" X 4.5" X 9" brick people are using that weigh 8#. My only other find was from Carolina Ceramics, "light duty," buff, 2.25" X 4" X 9" which only weighed 5.5#. I think the WG firebricks will work only I'll just need more of them due to the smaller size. Agree?

2. Are there any huge advantages/disdvantages to using the concrete/vermiculite mix vs Kaowool or Super Isol insulating board? If the latter is significantly better, where do you find it?

3. If you go with the concrete/vermiculite layer, why do the Pompeii plans call for it going on top of the concrete slab while the Alan Scott plans call for the concrete slab on top of the concrete vermiculite slab? Just curious as I'd think that the approach would be the same whether it was a dome or vault design.

4. Once you've laid your hearth bricks on the concrete/vermiculite, do you fill in the gap (the brick height) around the hearth with more concrete vermiculite to make it flush with the hearth height (to the edge of the slab) or do you just leave it as is to be filled later by loose vermiculite when you make the dome enclosure?

5. Is it worth making provisions during construction for thermocouples or do most people use a handheld IR unit? If the former, any advice of where to buy them and where to put them?

I'm sure I'll have more questions but could use some help on these so I get started right. Thanks.

Mark

[Breven]

Re: First Post - A Few Questions

Hey Mark-
Welcome aboard. I'll see if I can cover some of these for you- the forum has discussed most of thse many times, so if you search around you may find other opinions.

1. I used an 8lb fire brick. I think most people seem to use something that weighs in betwen 7 & 8 lbs. I think your first choice will probably work fine. I would go a little heavier rather than lighter.

2. I'm not sure about the board vs. the vermiculite layer- except that the vermiculite layer is dirt cheap compared to the board. I think the board probably insulates better, but I'm not sure its that much better to warrant the expense. Really, I think its just a cost issue here.

3. I don't know the Allen Scott plans, but I do know that a vermiculite layer is not a support layer, its an insulating layer. It makes sense for the concrete base (with rebar) to be under the insulating layer- so the insulation keep heat from escaping in to the concrete support. It would be like putting carpet under your floor instead of on top.

4. Not sure I understand this question...I'll skip it

5. I think most of the forum agrees that thermocouplers are a waste of time an money. You just don't need them. I bought a laser thermometer, works great- but as soon as you figure out how your oven heats up- you never really need to check the temp. Don't waste your time and $ on thermocouplers.