potential boo boo

[spinal tap]

I've been lighting the last curing fires. Today I had a fire going in the mid 600s. Two days ago, a crack appeared in the very front of the arch where it recieved the least heat. I figure it was the warm oven expanding and that area was not warm and not expanding and the crack was the "give". It was less than hairline in width, but I notice it getting to almost 1/8" as the oven got hotter. I couldn't leave well enough alone and tried to squeeze some mortar into that bitty crack. I wasn't successful in getting it into the entire crack, then I had to leave the house. Well, came home and the crack stayed the 1/8' because of the little bit of mortar I squeezed in (acting like a wedge). I'm wondering now if that crack will only get wider as I fire the oven up.

The top of the storage (just under the fire) up to today was always just slightly warmer than all the rest of the concrete averaging from 70-80degrees. I came home and just checked and it's 118 while the oven floor is just under 200 (fire has been out for 10hrs). Does this mean moisture is being pushed out of the bottom and slab?

thanks,
Nate

[brickie in oz]

Re: potential boo boo

I came home and just checked and it's 118 while the oven floor is just under 200 (fire has been out for 10hrs). Does this mean moisture is being pushed out of the bottom and slab?

Could be moisture, did you insulate underneath your oven floor?

[spinal tap]

Re: potential boo boo

Could be moisture, did you insulate underneath your oven floor?

yes, 2" ceramic FB.

[jab49]

Re: potential boo boo

Hi Nate
I'm thinking that the crack will have relieved whatever pressure caused it to happen. Unless it keeps expanding, maybe just leave it alone? Perhaps a photo could help in the diagnosis too?

[deejayoh]

Re: potential boo boo

Just about every oven on this site has cracks. You can post pix, but it is probably nothing to worry about. You might pick out the mortar next time you heat up the oven. It's not going to stay secure anyway.

[GreenBldr]

Re: potential boo boo

I have that same crack in my arch. It appeared when the curing fires got up to 600F or so. Because my oven is indoors, I contracted with a local fireplace installer to put an insulated stainless chimney on the oven. Once the chimney was installed, I was eager to get those fires going again and that's when the crack appeared. It seemed as if the newly installed chimney was bearing down on the oven arch and causing the crack to spread. Upon consultation with the installer, he said I could just loosen a clamp at the top and redistribute the weight of the tube if it was bothering me. When I got up there, I found that the clamp had never been tightened in the first place and the arch was, in fact, bearing the full weight of the entire chimney assembly during several heat/cool cycles.

So, I had someone fabricate some clamps that would suspend the weight of the chimney from surrounding structure instead of putting it on the arch. After that, the crack did not appear to spread any further. It goes from a hairline crack when the oven is cool to about 1/8" when it is hot.

I did show it to the mason who will be building the decorative arch out front and he said a couple things;
1) Once you cover it with something you get the benefit of not seeing it any more. Sort of along the lines of "out of sight, out of mind....."
2) He felt the act of putting the decorative masonry arch out front would support the oven arch so our worst fears would never be realized (that it would simply fall apart)

[spinal tap]

Re: potential boo boo

Thanks for replying to this old thread. After I posted this thread, I ordered some high heat caulk and squeezed it in the crack while it was warm. The front has since been covered by stucco so I don't see it anymore. I have peaked in there when I'm cooking with the oven and don't see it expanding.

I'd actually forgotten about it till this thread was bumped.

[Bravo]

Re: potential boo boo

Instead of starting another thread, I was hoping to add/bump this one with my own headache.

Attached is a photo of the door of my oven. As you can see, the crack near the door "frame" has removed a piece of the "frame" and prevents the door from fully enclosing the cooking area. I am not a mason and I don't have any idea of the feasibility of repairing this. Are there any ideas to consider or is this just hard luck?

This is not a FB oven.