Wet Oven Floor

[brickie in oz]

Re: Wet Oven Floor

Gudday
I don't see how a drain hole will allow water held in air spaces in the firebrick and insulation to escape. But I have been wrong before so its only a hole and I pull out the hammer drill this weekend.

Its so simple to add it to any oven that it make my brain hurt thinking about it.

[cobblerdave]

Re: Wet Oven Floor

Gudday
Ok it's on this weekend.... Who will win ...capillary action or gravity.
If gravity wins that slab is going to look like Swiss cheese.
Regards dave

[david s]

Re: Wet Oven Floor

If you placed a large sponge into a bucket, then drilled a hole in the bottom of it, excess water would have a chance to escape, although the sponge is likely to block the hole. It won't stop the wet sponge from holding water into itself. I think a drain at the bottom of an oven with a vermicrete slab is something similar. A vent hole at the top of the oven is a more effective way of removing excess moisture IMO.

I have a 100L woven plastic bag of 50/50 vermiculite, perlite that I left, with the top sewn up, out in the rain. It has sucked water up into itself and is about 50% heavier than a dry full bag. It has not rained for around two weeks. The capacity of this stuff to hold water is the reason it is used as asoil conditioner and hydroponic medium.

[ShuttleAU]

Re: Wet Oven Floor

Gudday
I don't see how a drain hole will allow water held in air spaces in the firebrick and insulation to escape. But I have been wrong before so its only a hole and I pull out the hammer drill this weekend. Lets hope I can beat the odds and miss the steel!
BC I wish it was as simple as a piece of plywood. Problem is around here we get regular summer storms so any thing like that would have to be solidly fixed. The chimney cap is 750mm x 250 mm opprox and was taken by one storm over the fence into the neighbors... It made of tin ,truly scary if that hit anyone. It now has the 3 firebricks on it.
Now the problem really is how to fix something vertically to the mouth of the oven..... And non ugly ?
Regards dave

Yep, we have had a few good storms recently and the tornado near Kiama. I will try and take a photo of the plywood. It is shaped like a "D" and fits just into the arch entrance. It does need a coat of paint. The one that got my oven was 70mm overnight from the North which is largely unheard of in Sydney.

BC

[Kurtloup]

Re: Wet Oven Floor

This discussion on wet insulation has me wondering if I should stick with the perlite board I have Sproule-WR-1200 as it is non-wicking. It isn't as efficient as the Calsil board I planned to swap it for today, but is that a good trade off? I can double up to 4" if needed.

[Laurentius]

Re: Wet Oven Floor

No. Go with Calsil or ceramic fiber.

[Kurtloup]

Re: Wet Oven Floor

Well, I went by the insulation supplier and bought 1.5" Calsil board to go on top of the 2" Perlite board. The 2" Calsil had grooves cut in it for wrapping around pipes. This will give me 3.5" of insulation. Maybe the Perlite board will prevent moisture wicking up from the concrete hearth into the Calsil?

[Laurentius]

Re: Wet Oven Floor

The perlite board is probably more prone to wicking than the Calsil.

[Kurtloup]

Re: Wet Oven Floor

You may be right, but all I have to go on is the information from the supplier and the manufacturer. The supplier told me that the product will not absorb water. The same manufacturer, IIG, also makes the calsil board I purchased and doesn't mention the calsil board being non-wicking, but it does say that about the perlite product:

Sproule WR-1200? is a pre-formed, high temperature, non-wicking
pipe and block insulation composed of expanded perlite uniformly
reinforced with a high strength fiber for use on systems operating up to
1200?F(650?C).

[brickie in oz]

Re: Wet Oven Floor

Sproule WR-1200? is a pre-formed, high temperature, non-wicking

Maybe they mean non heat wicking?

[david s]

Re: Wet Oven Floor

Some perlite gets treated with silicon which makes it non absorbant. This is probably what the manufacturer uses. I wish I had access to some.

[rosewood]

Re: Wet Oven Floor

I in Ohio, Youngstown, and have noticed the same mositure problem in my casa2G90. I followed the forno bravo instructions for construction and also have decorative stone over the entire oven. I see no way moisture getting in other than through the chimney and possiblly the front from rain or moisture in the air.

I also have noticed that if I don't clean out the dry ash after a burn that the ash is like mud the next day. I'm thinkng this may just be from humidity in the air. In fact I just discovered today that if I leave the door to the oven tightly closed, mold will begin to develop. I'm not sure how to prevent this. Here are my questions.

1. Is it better to leave the opening to the oven open, partialy open, or closed when not in use?
2. Would it be a good idea to keep a natural drying agent like rice in the oven when not in use?

I'm going to do a burn to clean it out, but not sure what else to do to prevent this or if this is normal.

Hope to hear from anyone on this topic.

Joe

[cobblerdave]

Re: Wet Oven Floor

If you placed a large sponge into a bucket, then drilled a hole in the bottom of it, excess water would have a chance to escape, although the sponge is likely to block the hole. It won't stop the wet sponge from holding water into itself. I think a drain at the bottom of an oven with a vermicrete slab is something similar. A vent hole at the top of the oven is a more effective way of removing excess moisture IMO.

I have a 100L woven plastic bag of 50/50 vermiculite, perlite that I left, with the top sewn up, out in the rain. It has sucked water up into itself and is about 50% heavier than a dry full bag. It has not rained for around two weeks. The capacity of this stuff to hold water is the reason it is used as asoil conditioner and hydroponic medium.

Gudday Dave
I have drilled a few holes in the bottom of my slab and at first .....nothing. Couple of light firings later the water pissed out. So I think I'd change the discription. Take a bucket place a wet sponge at the bottom seal the top then take to it with a blow torch and the water will come out the bottom. It certainly goes to show how long it takes for the heat to get through.
Still agree that the vent at the top is a must especially if you have ceramic and rockwool like myself.
Have added a a wheather door to the front entrance and it certainly keeps the water of the hearth. Prevention is better than cure I suppose
Regards dave

[rosewood]

Re: Wet Oven Floor

This is just a thought for once the unit is built, but has anyone thought about keeping a natural absorbant like rice in the oven when not in use ust to keep the moisture out. Obviously this wouldn't work for large amounts of water, but It may work for general dampness in the air. Right now the air in Ohio is very humid. Even with little to no rain in a few days, the inside gets damp if I keep the door tightly closed.



Joe

[david s]

Re: Wet Oven Floor

yes, I have a hole in the bottom of my supporting slab for this reason too. When installing a new kiln at our school the installation requires firing up the empty kiln slowly to operating temp. When the kiln reached 400 C water was dripping from the bottom of the kiln making a puddle on the floor. I guess the pressure will force the water out wherever there is a hole. It generally travels in a direction away from the heat source, then when it strikes an impervious cooler layer it condenses if it can't escape.