Casa 2G100 losing heat

[Cinci-za]

Greetings Fellow Pizza Fan.

I built a casa2g100 almost two years ago, and i have had a problem retaining heat. I can get the dome to clear after some roaring fires, and with proper wood selection. I can't get the surface of the oven to get hot though. Even when i move the coals, the temperature will be around 350-400 under the coals. It seems like i am not getting good heat retention and maybe reflection off of the dome. thought this might be moisture, and maybe it is, but seems to happen even when i am using it frequently. It is a dome design covered in stucco with the fb insulating blanket underneath. My worry is that i didn't seal the pieces of the dome well enough at the seams, and am now losing heat through there. the stucco does seem to get warm there, around 140F. I was considering some sort of patch, or fire place caulk between the seams on the inside of the oven, but didn't know if this would adhere, and solve the problem.

Any advice out there?

[texassourdough]

Re: Casa 2G100 losing heat

Is the stucco hot? If it is then it is water OR a leak like you suggest. But???? I doubt it. You cite the temp of 350 to 400 as though it is the dome temp. What is the temp of the dome? If it clears the dome is at least at 700. How are you measuring the temp? Only an infrared is of any real value for measuring the hearth and dome temp.

If the temp of the hearth is 350 or 400 you are letting ashes accumulate and insulate the hearth OR you have a leaky hearth.

Without more information no one can answer your question with any confidence.

[Cinci-za]

Re: Casa 2G100 losing heat

Thanks for the reply texassourdough!

I am using an infared gun to measure the heat. The dome clears and exceeds the max on the gun. 900 i think? The hearth floor will maybe get 500 for a bit, and loose heat, even if i have a good flame going around it. Even if i move the hot coals, the surface will be around 400.

I usually don't brush the hearth until the oven is hot and i am ready to bake. Would residual ash cause that much insulation of the hearth.

It is constructed based on the instructions. hearth is on the provided insulated board, and that is on a concrete slab. The whole thing is encased in stucco concrete and insulating blanket.

Thoughts?

[david s]

Re: Casa 2G100 losing heat

If the outside of your oven is hot to the touch and the floor not getting up to temp I would be suspecting a wet oven. If your oven is outside in the weather it can pick up a lot of moisture which will accumulate in the bottom part of the oven. If the under floor insulation is wet it will not insulate properly. Try feeling the supporting slab from the underneath to feel if heat is going through to there. If this is the problem you can fix it by just firing it more. Also inspect around the base of the dome to ensure there are no cracks there where water flowing off the dome can enter under it and collect under the floor. Another common entry point is around the flue pipe. If this doesn"t help call FB directly and get some advice from them.

[texassourdough]

Re: Casa 2G100 losing heat

It is hard to believe that ash is the problem but...ash is a superb insulator so if there is a bed of ash it will contribute to the problem. Wet is more likely (as David suggests) given you have the insulation board. (I missed that somehow on the first read!)

Dome issues would not affect the hearth temp. If you are clearing the dome you are fine. I would go with some long burns to insure the hearth is reasonably dry. By long I mean three or four hours minimum to make sure the heat is pushed deep into the hearth and to dry it out. That should also resolve any questions about the dome. If the hearth is wet it can heat the dome. I would also second David's suggestion of going over the dome and key weak points (flue and any horizontal surfaces) to make sure they are sealed.

Good luck!
Jay

[Cinci-za]

Re: Casa 2G100 losing heat

Thank you both for the advice.

I will build some long fires this weekend, and see if I can dry it out.

I might also build a door that covers the entrance way a little more. Figure that will protect the hearth from the elements.

[Neil2]

Re: Casa 2G100 losing heat

"If the outside of your oven is hot to the touch and the floor not getting up to temp I would be suspecting a wet oven"

I think David and Jay have identified the most likely problem. Water sitting under your hearth in the insulation layer on top of your structural slab can take a long, long time to drive out.

Try the steps that David suggests. One thing to consider is that a "bathtub" type depression exists in your structural slab that is holding in the water. If all else fails to solve your problem, you can consider drilling a few small (3/8 inch or so) holes up through the slab into the insulation layer to provide drainage.

[Cinci-za]

Re: Casa 2G100 losing heat

Interesting, i had never considered that. Everything looks tightly sealed around the base of my oven. It sits on a slab of concrete underlined with concrete board. I can't imagine how water would pool underneath the hearth.

[Neil2]

Re: Casa 2G100 losing heat

As concrete initially cures, it shrinks. This will tend to leave a slight depression in the middle and a slightly raised "edge". Even a 1/4 inch depression will trap a lot of water.

This should be checked for (by flooding the slab) prior to placing the insulation.

I'm not saying this has happened, it is just one more thing to consider if you continue to have problems.

[Laurentius]

Re: Casa 2G100 losing heat

Hi Cinci-za,

If your landing is of fire bricks, which are very porous, soaks up rain which leaches into your ceramic fiber board. You will encounter a heat management problem.

[david s]

Re: Casa 2G100 losing heat

Obviously too late now, but when laying the supporting slab it is a good idea to make it slope slightly down to the corners so that water will not drain towards the centre of the oven and then under the floor. Also a water barrier under the slab between it and the stand will prevent water wicking up through the stand. Do this for your next build.

[Neil2]

Re: Casa 2G100 losing heat

This is more of a far out, less likely possibility;

Capillary rise in concrete can reach 5 to 6 feet. If your footings/slab are below the local water table (do you water the lawn near the oven ?) you can get moisture migrating up into the oven.

The solution is to ensure you have positive drainage at the bottom of your footing/slab.