oven Not hot enough

[david s]

Re: oven Not hot enough

If your oven is new and still contains lots of moisture it won't be getting hot on the bottom. One hour of fire is not particularly long, without seeing the design and knowing the insulation it is hard to make a judgement, but it may be ok and you might just need more and longer fires to get operating ok.

[Neil2]

Re: oven Not hot enough

I think wotavidone has hit on your only viable option.

Block the existing chimney flush at the bottom. Try for a door to dome height ratio of 63%.

Try it that way. If it seems to be working, then add an external vent as per wotavidone' sketch.

What sort of insulation do you have under the hearth and covering the dome ?

[texman]

Re: oven Not hot enough

David
Is your oven built without brick and using heatstop only as the oven material?

Tex

[wotavidone]

Re: oven Not hot enough

David,
First off, see Davids's reply on page 2. Is it dry yet? It takes quite few fires to get the residual moisture out. And he's right - even perfectly proportioned ovens often require more than an hour of flames to get hot enough for pizza.
Another poster asked a very relevant question - what exactly is this baby made of?
The other thing I notice about your oven is that it is very high inside if you want to cook pizza in it.
If I read your door and internal dome heights correctly, it is 14 inches for the door and 19 inches for the dome, for a ratio of 0.74, and your dome ceiling is a long way from the floor, so not much heating of the floor.
In an ideal world, the dome height is only about half the oven diameter for a general pupose oven and something less than half if your main dream is hardcore pizza cooking.
If you can get some insulation and bricks, even just borrow them for a try out, or use ordinary house bricks to see if it works before buying proper fire bricks, try this.
If you were to put a 2 inch layer of insulation on the floor of your oven, then a 2 inch layer of bricks, you would end up with a 10 inch door height and a 15 inch dome height.
Ratio of door to dome is then 0.66, much closer to the 0.63 considered optimum.
My theory is most of the floor heating comes from radiated heat from the ceiling of the dome, so if you want a hot floor it has to be reasonably close to the dome.
Regards,
Mick

[david s]

Re: oven Not hot enough

If you used 13 bags of heat stop mortar to make the oven, then you have added a very large quantity of water and as your walls are 4" thick it will take a long time to eliminate all the water. The remedy IMO is not to make drastic changes, but to just continue firing and the oven will come good when it is finally dry. Without the addition of fibres designed to melt and burn away at low temp, in the mix you risk steam exploding your walls so be careful.
The second two ovens I built were of the same design that you have and I was surprised that they did not operate as well as my first design which had its flue in the centre of the dome. I've found the best design is one with the flue at the front, but independent of the oven chamber. Don't give up or drastically change your design, I'm sure the main problem is that your oven is not properly dry. I bet it is still smokey, that's another sign of a wet oven.

[david s]

Re: oven Not hot enough

You can also simply control the draft by placing a tile on top of your chimney to partially or completely close it. This is how we control the atmosphere when firing kilns.

[wotavidone]

Re: oven Not hot enough

The remedy IMO is not to make drastic changes, but to just continue firing and the oven will come good when it is finally dry. Without the addition of fibres designed to melt and burn away at low temp, in the mix you risk steam exploding your walls so be careful.
The second two ovens I built were of the same design that you have and I was surprised that they did not operate as well as my first design which had its flue in the centre of the dome. I've found the best design is one with the flue at the front, but independent of the oven chamber. Don't give up or drastically change your design, I'm sure the main problem is that your oven is not properly dry. I bet it is still smokey, that's another sign of a wet oven.

Very good advice - definitely pursue this before making any structural/design changes.

[deejayoh]

Re: oven Not hot enough

Very good advice - definitely pursue this before making any structural/design changes.

+1 on more fire. Dry it out slowly, and then get that baby stoked up. Tear down and rebuild is a last resort.

[firecapt]

Re: oven Not hot enough

Really really new to all of this, but could his wood also be an issue? I was thinking that wood that wasn't totally seasoned could contribute to the large amount of soot present, and lower temps. I might be way off...just a thought. Good luck

m

[texman]

Re: oven Not hot enough

I am thinking his oven is cast from heatstop mortar only. While the water is definitely and issue, I don't think mortar has the properties to store heat anywhere like a dense firebrick. I think we need his response to know exactly what this thing is.
David S and Wotavidone or right on if he has some brick in there. Really like to know.

Tracy