Oven not heating

[JD07]

Hey guys I built my oven in 2010 and have done many sessions in it including whole lambs however of late I am not able to get the dome or floor hot enough. I did a slow cook lamb shoulder today but after 2 hrs the dome was still black and was only 170 - 180 degrees??? The floor was less than this?? Given pressure from the wife I just threw the shoulder in and it went ok but she is just not on form like she used to be.

I really am not sure where I am going wrong as I am following the same routine. We have had many months of rain here and the dome has no roof over it so I am thinking porous brick and cement could become water logged but I am not seeing any telltale steam coming from the dome pipe that I put through the render into the insulation?

She is made from refractory half bricks with a layer of insulation and then render then tile? The dome height to door height follows the right size although the door is a touch wide.


I know that if the dome is not white I am not getting the temp and will take a night later in the week just to see if I could get it to go white. But I was hoping that perhaps people had run across a problem similar to this.

[david s]

Re: Oven not heating

You are correct, your oven has water in it. Just fire it more and it will dry out. You don't need to go right back to square one, just keep a gentle fire going all day if you can. After a few firings it will be back to top performance again.
We live in the tropics and although the oven is well waterproofed moisture still gets in, probably some down the flue from driving rain, some in the mouth and the rest from absorption from 100% humidity. Ours was actually mouldy inside, but some fire fixed that.

[Neil2]

Re: Oven not heating

If you are not seeing any steam coming out of your vent, it may be because the insulation hasn't gotten hot enough yet.

As David says, just keep at it with curing fires.

[brickie in oz]

Re: Oven not heating

I can see in the pic that the oven is wet, the bricks below the fire bricks in the hearth are drenched.

[JD07]

Re: Oven not heating

Thanks guys

Buy the way that photo is years old from the build photos it doesn't look like that today.

[brickie in oz]

Re: Oven not heating

So show us some modern pics....

[david s]

Re: Oven not heating

One place where water can enter is where the base of the dome meets the supporting slab on the outside. Often because of the movement, a small crack develops there. With water running down the dome to that point, a fair amount can enter there. Seal around this spot. It would be too late now, but a slight slope to the outside also helps in draining this water away from the base of the oven.

[JD07]

Re: Oven not heating

After I finished last night I left a good fire going and went out around 10pm and the dome was warm to the touch. I am going to fill her up tomorrow night and let it burn through the night

[C5dad]

Re: Oven not heating

Just keep a low to moderate heat on. I suffer through the same thing since I cannot decide on how to enclose. I just fire the oven and forget about it. Sucks, but works.

At least now I have a plan - collect stone and start enclosing next week!

[cobblerdave]

Re: Oven not heating

Gudday
If you don't want to go to the bother of building an enclosure or overhead cover or like me like the dome look, there are a number of things to minimise this happening again.
"Bondall" sealer is easy to abtain and will seal the dome and entrance brickwork ..its clear and will not change the colour or make the finish shiney.
Chimney cover... if its not covered in some manner the water drops on your hearth bricks and those are pretty porous.
Check the tiles around your dome if the water pools here it will get in your base and insulation. If this is good you can also seal the grout inbetween the tile with bondall sealer.
Check for any cracks in the dome particularly where the dome meets the chimney/ entrance. Any cracks here can be widdened with a angle grinder and filled with paintable silastic and refinished.
And finally consider a cover at the entrance where any rain can be blown in.

Hope something here helps

Regards Dave

[Mike D]

Re: Oven not heating

-I would say the same thing as the guys above. Dry out your oven and at least put a tarp over the oven in the rain.
-You could of gotten rain inside the oven, under the floor in the insulation. Give it a long slow fire and see if that helps.

Mike

[Neil2]

Re: Oven not heating

"It would be too late now, but a slight slope to the outside also helps in draining this water away from the base of the oven."

David has a good point. Concrete is very porous and hard to keep sealed. If possible, grind the flat exposed part of your suspended slab so that you have positive drainage away from the dome.