brick or fire brick

[juliac121]

Re: brick or fire brick

In ovens normal bricks will heat up, retain heat, cook, bake, roast, re-fire, absorb conduct store and hold the heat from wood fire and perform the same way as fire bricks do, but normal bricks are not as hard and durable as fire bricks. Additionally, normal bricks do not conduct heat as well as fire brick and may take longer to reach adequate cooking temperatures.

[oblertone]

Re: brick or fire brick

Another vote for a red brick dome for domestic use, especially given the price differential. Spend the money on insulation and beer.

[david s]

Re: brick or fire brick

If these bricks of yours have been fired at 1100F you will have no problems with your oven.

I think you probably meant 1100 C.
1100 F is only just enough to make the clay permanent, ie. no longer turns back to mud when soaked with water. At 1100 F is not even enough to burn out the carbon if fired in a wood fired kiln.

[atb trev]

Just a bit of info on my 36inch clay brick oven.
I had loads of bricks lying around my property so decided to build a WFO. There are a mixture of types, but 90% are what's called Engineering brick in the UK - denser and stronger than normal bricks. The floor is made from storage heater bricks my dad was throwing out.

I've insulated, but not rendered yet so it's covered with a tarp. I've been happily using the oven for the last few months though and this is the typical performance I've been getting.

Insulation: - 4 inches of Calsil under the floor.
-4 inches of ceramic fibre over the dome.

Firing: From cold to dome clearance takes somewhere between 1hr and 1.5hrs.
The dome will get to somewhere just over 550C (my thermometer doesn't go beyond that).
The oven floor is often a bit less. I haven't been patient enough to wait for absolute full saturation yet!
This is plenty hot enough for pizza and they cook in a minute or two.

Heat retention:
I've not made a door yet, but have blocked the opening with bricks after firing and stuffing myself with pizza. I tend to lose 150C a day with this method.
When I wrapped some calsil board and put that in the door, this improved to 100C heat loss a day so I would expect slightly better performance when a door is finally fitted.

My aim was always to get a weekends cooking so it looks like my oven is performing well enough for that and I'll be aiming for
Day 1 (evening) - Pizza 500C
Day 2 - Baking/roasting at 350-300C
Day 3 - Baking/roasting at 200-250C

I'll let you know if I actually manage this, but the initial signs are that this is feasible.

I hope this info helps someone out there who is wondering about the performance of clay bricks.

[fremen325]

I chose to use firebrick. I was able to find light duty firebrick at USD $1.35/each. I ended buying 300 bricks total but have about 40 left over after building a 42 inch oven. While Red common brick is cheaper (I think it runs $0.95 at the home improvement stores), I figured it was better to use the right brick considering how much time the build was going to take. If you take into affect your hourly billing rate, the difference in material cost between common and firebrick is negligible in comparison to your time value in doing the build.

[oblertone]

G

I chose to use firebrick. I was able to find light duty firebrick at USD $1.35/each. I ended buying 300 bricks total but have about 40 left over after building a 42 inch oven. While Red common brick is cheaper (I think it runs $0.95 at the home improvement stores), I figured it was better to use the right brick considering how much time the build was going to take. If you take into affect your hourly billing rate, the difference in material cost between common and firebrick is negligible in comparison to your time value in doing the build.

You make a very good point regarding the relative costs of the two bricks, however most UK oven builders can source red clay bricks for little or no money as they are the 'standard' building material here. Mine came from a neighbour after they demolished a 200yr old chimney, free for the labour of cleaning them up.