Getting to cooking temp.

[mn8tr]

I have not had the opportunity to do a lot of cooking since our WFO has been finished. I have been able to hit 350 - 400 (on the cooking surface) within 20-30 minutes but it has taken as much as 2 hours to reach a floor temp of 550 and higher.

I have a 32" inside surface 16" high dome. the opening is 10 1/2 inches high,14" wide with a 16" deep tunnel

This is how I have been building my fire. Stacking newspaper and kindling (stacked in the center) followed by small split oak and then adding larger pieces as the fire builds. Once the large split logs (2-3) are burning I then push the burning logs aside and allow the fire to re-establish before adding any additional fuel.

What I have not yet done is build a real inferno from the very start... I wonder if I just answered my own question. Any suggestions ? ? ?

[RTflorida]

Re: Getting to cooking temp.

Have you gone through the entire curing process and are ready to go inferno?
If yes, you need more wood, 2 -3 splits is only good for a marshmallow roast.

There are many ways to build a good, big fire. your method is fine, just add more wood until you reach the scary fire level. I've read where a couple of members actually pack their ovens with wood at start up, I have not had much luck with that approach, seems to take twice as long and burns unevenly until about an hr has ellapsed.
I use the top down method, starting with 3 - 2-3" logs on bottom and progressively work upwards with smaller branches and kindling, with crumpled newspaper on top. I start my fire where the entry meets the dome, getting the flue hot then gradually push it back over the first 15 minutes. Then I start throwing in the big stuff. within 1/2 hr I usually have a raging fire and can burn the dome clean in about 50 minutes (from start to finish).

RT

[ThermoJax]

Re: Getting to cooking temp.

I have been done with my oven for a month or so. I think you should be oven drying your next batch of wood. That means get a door. I also think you should get a really small log stand/grate. Get some air under your fire. Also, get your wife's blowdryer. That really helps get you up to temp much quicker. And it is loads of fun. I show of with party guests showing how the oven roars and occassionally goes "woof" when I hit it with a blast of the blowdryer when I haven't messed with it for a couple of minutes, then blast it low down on the fire, but direct. The flame will leap out of the front arch and will hopefully make the "woof" sound.

All the above should do the trick. (be sure to have dry dry dry wood. Don't waste those BTU's boiling off water)

[mn8tr]

Re: Getting to cooking temp.

Thanks for the advise, I am going to have to try the top down method. This weekend there WILL be a 4 alarm dome fire, and I will have the garden hose on stand by.

[Lburou]

Re: Getting to cooking temp.

Looking at your beautiful oven pictures, (a little oven envy going on here ), I'm wondering where the opening to your flu is located?

How high is the opening of the flu and how high is your dome? Relative to other oven builds, it looks like your flu is further up the dome than the usual build here....That could let most of the heat out the chimney. Hope I'm wrong about this.

A Husker fan here....You have to be a cool guy to be a Husker fan in Texas

[DrakeRemoray]

Re: Getting to cooking temp.

Nice looking oven, but I think you may have a couple of fundamental issues, though it is a little hard to tell...
Please keep in mind, I am not trying to be a jerk, but point out issues only so that others might avoid them in the future....
First, it looks like you sort of made your own design, and did not follow the pompeii plans. A lot of trial and error has gone into those plans so we mostly suggest following those...that said, here are the two main problems that I would ask you about:
1) Do you have any insulation under the floor? it looks like you built the floor directly on the support slab in this picture but maybe this is just a mockup of the build...

If you do have insulation under the floor, what type and how much. Looks like you have a good insulation on the top of the dome, so that will help a lot.

2) Your chimney and flue appear to be inside your dome instead of in the entry way. You will lose a lot of heat out of the dome with this design.



These two issues make make it take longer to get up to temperature, but you will still get a lot of enjoyment out of your oven. Let us know about these questions and how it goes after you make a really big fire.

Drake

[mn8tr]

Re: Getting to cooking temp.

The bottom of the flue is 10 1/2" from the oven floor and the dome height is 16". It is a little deceiving but the fire brick arch has a half round opening for the flue. The total flue stack height is 16"

The floor is a 5" slab of vermiculite / concrete, I added a thin layer of utility sand for leveling the brick floor. I have been monitoring the underside temp and has never gotten above the ambient air temp.

I think you may be right about the flue placement. The 6" opening for the flue is half in the arch and half in the dome with the low point being 10 1/2". I do have a damper that I can experiment with to try and curb the heat loss. I recall seeing several ovens with the flue in the back and even in the top. I guess that they are having problems too. I refuse to panic until I have built the really booming fire to see where that leaves me.

Thanks for all of the input.

[fxpose]

Re: Getting to cooking temp.

I believe Primaveras are designed similarly, where the flue is somewhat 'within' the dome but its opening (flue intake) is much lower than the dome ceiling and that seem to work well there.
The only 'problem' with that design is that you can't really store residual heat with a door unless you find a way to isolate the flue intake from the dome. Capping the flue at the top will help and is probably the most practical solution for storing heat.

[Lburou]

Re: Getting to cooking temp.

The bottom of the flue is 10 1/2" from the oven floor and the dome height is 16". It is a little deceiving but the fire brick arch has a half round opening for the flue. The total flue stack height is 16"

The floor is a 5" slab of vermiculite / concrete, I added a thin layer of utility sand for leveling the brick floor. I have been monitoring the underside temp and has never gotten above the ambient air temp.

I think you may be right about the flue placement. The 6" opening for the flue is half in the arch and half in the dome with the low point being 10 1/2". I do have a damper that I can experiment with to try and curb the heat loss. I recall seeing several ovens with the flue in the back and even in the top. I guess that they are having problems too. I refuse to panic until I have built the really booming fire to see where that leaves me.

Thanks for all of the input.

Your statistics reassure me that there is hope! Don't panic until you build the mother of all fires and see how the temperature rises

[brickie in oz]

Re: Getting to cooking temp.

Wont you lose all you heat out of the flue being positioned the way it is?

[Lburou]

Re: Getting to cooking temp.

Wont you lose all you heat out of the flue being positioned the way it is?

He'll know when he builds that huge fire and lets it burn....

[mn8tr]

Re: Getting to cooking temp.

[I]Wont you lose all you heat out of the flue being positioned the way it is?[/I]

It is actually more isolated than it appears to be. The way that I framed the brick for the flue opening I can add a brick with a 6" half circle that will bring 100% of the flue opening at 10 1/2" height. I have hope.

[fxpose]

Re: Getting to cooking temp.

I believe that would do the trick. Your flue opening and inner arch should essentially be even in height in your particular situation.

[lwood]

Re: Getting to cooking temp.

Your door opening is 65% of your dome height. Combined with the flue placement, it seems that you are pouring all the heat out of your opening and up the flue. The first time I saw that oven it seemed that the opening was disproportionately large for the height of the oven and the strange flue placement. I think you did a beautiful job on the rock-work and finishing, just the dimensions are off a little IMHO, sorry to say. I believe you are just on the design edge of the oven not working. I could be wrong and I hope I am. If so, I think the remedy is to make a slightly shorter opening height and/or move the flue farther out-board of the dome.

Thought about this for a while before posting bc I have never seen a posting here that said it won't work and I certainly am no expert. However, I thought about if it were my oven, I would want someone to tell me if it weren't going to work or if I was going to pour tons of wood into it to keep it hot.

[mn8tr]

Re: Getting to cooking temp.

I do not have another oven to compare mine with but I am happy to report that all is well in Pearland. As it turns out I was not being aggressive enough with the fire. We build a real inferno yesterday and made it to a 700 degree cooking surface in 50 min. with no problem. I did however get my first crack, bummer. Not to worry the pizza was great, and the crack can be fixed.