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-   -   Help! Trying to make the best of a bad situation (http://www.fornobravo.com/forum/f8/help-trying-make-best-bad-situation-4864.html)

Sam 08-21-2008 07:55 PM

Help! Trying to make the best of a bad situation
 
My Father had someone build him a WFO. After some investigating I came to the conclusion that it was created with a major flaw - no insulation.

Thanks to this forum, I have been reading as much as I can over the last couple of days and I am trying to make improvement to the current design. I know there are few options but I hope this is not a lost cause.

Any recommendations would be appreciated.

First the design...

The Oven was created on a cement slab of about 5-6 inches thick. The fire brick was laid with mortar directly on the slab. The bricks were joined with a high temp premixed glue. The dome was constructed directly on the fire brick bed. Once again the joints on the inside of the dome are being held together with the high temp glue, the larger gaps to the outside of the dome are filled with mortar.

Once the dome was completed it was covered with 2" of mortar.

Currently the dome is exposed (phew!) and this will allow me to insulate the dome. I purchased locally in Toronto a 1" ceramic blanket that I plan on placing directly on top of the dome. I also bought 1 bag (4 cubic feet) of vermiculite (I will probably need more) that I plan on placing on top of the blanket. I am not sure if I can place it as is or if I should use some type of mix configuration. Once this is done, I will ask them to continue to close off the oven.


As for the oven floor, I realize that the floor will not maintain heat in its current state. I am trying to figure out the best solution.

I can think of two options....

1) insulate under the concrete slab. This may help a little but my limited research suggests that this might not be that helpful.

2) purchase 2" insulating board and place it above the current firebrick and then place another course of fire brick on top. Cutting the firebrick to fit perfectly might be a problem but I think I will be able to manage. I also realize that I will be eliminating aprox. 4-5 inches of height. I think the oven can easily accommodate this without causing a problem.

Any suggestions would be greatly appreciated.

Oh, I almost forgot... What is the best way to secure the insulating blanket to the dome? I see some people use chicken wire. What other methods are there?

dmun 08-21-2008 08:30 PM

Re: Help! Trying to make the best of a bad situation
 
Insulation under your slab will only help slightly, if you have a high dome oven the raised floor with the cal-sil board is the way to go. Cutting firebricks is not that hard with a wet saw. A combination of blanket and vermiculite is the standard dome covering, and yes, chicken wire helps keep the blanket in place, and gives the vermiculite concrete something more to grab on to.

Good luck, keep us posted.

mfiore 08-21-2008 08:33 PM

Re: Help! Trying to make the best of a bad situation
 
Sam, how much height within the oven do you have to work with? I agree, raising the floor is likely your best option. Cutting the fire brick to fit precisely should not be too difficult.

Les 08-21-2008 08:40 PM

Re: Help! Trying to make the best of a bad situation
 
Sam,

It sounds like insulating the dome is not a problem - I used baling wire to hold the blanket in place, then covered the dome with chicken wire for the vermiculite. The floor is your ugly. If you can go vertical, option 2 sounds best to me. If it's a squeeze - you may get away with splits for the brick.

Also, I would try and sue the dude for being and idiot or for trying to impersonate someone that knows what the hell they are doing! You are in Canada so I have no clue as to what the law is all a boot. :)

Les...

Sam 08-21-2008 08:41 PM

Re: Help! Trying to make the best of a bad situation
 
I am not sure of the dome height. I will try to visit my parents in the morning to measure and take some pictures. If I were to guess...about 24 inches.

I was leaning towards loose vermiculite. Should I change this to a vermiculite and portland mix?

Thanks

Les 08-21-2008 08:42 PM

Re: Help! Trying to make the best of a bad situation
 
WOW! While I was composing - 2 others chimed in, you are in good hands.

Les...

maver 08-21-2008 08:46 PM

Re: Help! Trying to make the best of a bad situation
 
Just for a point of reference for what you are trying to avoid, my father also has an uninsulated floor placed on a concrete slab with an uninsulated dome. His oven is able to be heated to pizza temps, but it take 2-3 hours vs about an hour for mine. During those 2-3 hours he has to feed the oven quite a bit of wood. Incidentally, his vent is from the top of the dome rather than over the opening as most use here. His dome is (I think) 46" and he needs the extra room because he has to keep a very big fire. All that said, his pizza is very good and was enough to inspire me to build my oven. I believe the dome insulation (and avoiding a vent in the dome) are the most important steps. If you can also insulate under the floor bricks as well you are golden.

CajunKnight 08-21-2008 10:35 PM

Re: Help! Trying to make the best of a bad situation
 
onething to keep in mind when adding board and brick to floor... is door going to be high enough? and if dome isnt covered yet would it be possible to relocated vent to arch opening?

toddj 08-21-2008 10:50 PM

Re: Help! Trying to make the best of a bad situation
 
Can you lift the slab/oven off the stand with a forklift, then pour a new concrete slab, insulate it with some ceramic board, then set the old slab/oven on top. It would give you a lot of mass to heat but it would work.. Then you would insulate the dome like normal..

Sam 08-21-2008 10:59 PM

Re: Help! Trying to make the best of a bad situation
 
Quote:

Originally Posted by CajunKnight (Post 39673)
onething to keep in mind when adding board and brick to floor... is door going to be high enough? and if dome isnt covered yet would it be possible to relocated vent to arch opening?

My Dads vent is located at the arch opening. That they got right (Mavers Dad had the vent issue). As for the door opening... It should be fine...


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