Thermal break between dome and chimney box

[mrchipster]

Re: Thermal break between dome and chimney box

The question is, how big a gap is too much? And, where does the thermal brake do the most good?

Not having a great deal of experience in thermal transfer I do not know but I believe you are on the right track and since your oven is built and you have experimented I will strongly consider your experience. Many thanks for your insights.

Chip

[david s]

Re: Thermal break between dome and chimney box

This is where I placed mine. I filled the bottom with 7:1 vermicrete which has some elasticity, did the same at the top, but didn"t worry about filling the sides. Because of the design of my floor, I couldn't put the gap at the inner end of the entry.

[mrchipster]

Re: Thermal break between dome and chimney box

Any thoughts?

One other important thought. an L shaped brick like you propose will induce significant stress at the corner I highly recommend a smoother transition for your corner. Cutting a near 45 degree angle and then smoothing the transition with a grinder might be the way to go.

Chip

[GianniFocaccia]

Re: Thermal break between dome and chimney box

an L shaped brick like you propose will induce significant stress at the corner

You may be right. My initial thoughts are that a hemispherical entryway will stand on its own weight, simply butted up against the oven inner arch. A workaround for the L-shaped tab might be the near-45degree cut brick with a shallow angle cut filled with high-temp silicone. Another option might be a stainless steel insert, an option for me because of a brother who is highly skilled at fabricating all kinds of steel.

I guess great minds think alike, yes? I have two designs in mind for the stainless steel entryway floor, again to be fabricated by my bro. I like the idea of sealing the door with ceramic rope. Here is my idea of incorporating it into the (FB designed) door instead of remaining exposed to elements.
John

[mrchipster]

Re: Thermal break between dome and chimney box

You may be right. My initial thoughts are that a hemispherical entryway will stand on its own weight, simply butted up against the oven inner arch. A workaround for the L-shaped tab might be the near-45degree cut brick with a shallow angle cut filled with high-temp silicone. Another option might be a stainless steel insert, an option for me because of a brother who is highly skilled at fabricating all kinds of steel.

I guess great minds think alike, yes? I have two designs in mind for the stainless steel entryway floor, again to be fabricated by my bro. I like the idea of sealing the door with ceramic rope. Here is my idea of incorporating it into the (FB designed) door instead of remaining exposed to elements.
John

I made a modification to the sketch in a couple of ways.

1) I believe the L shape is very strong just not a sharp corner at the 45.

2) hi temp silicone might be a good idea I do not know what it is heat rated for.

3) Take out the first metal flange from the door removing the U and leave the outer edge an L shape for the rope to sit in.

I like design 1 for the floor as it keeps the entry devoid of things that will catch the oven tools.

Chip

[david s]

Re: Thermal break between dome and chimney box

Stainless steel at the entry on the floor level is a good idea to prevent abrasion and many commercial ovens have this, but stainless is way more conductive than brick so is somewhat self defeating if the objective is to reduce heat conduction.

[mrchipster]

Re: Thermal break between dome and chimney box

Stainless steel at the entry on the floor level is a good idea to prevent abrasion and many commercial ovens have this, but stainless is way more conductive than brick so is somewhat self defeating if the objective is to reduce heat conduction.

A thin piece of stainless in contact with the brick floor will not transfer much heat because the contact point will be minimal less than 1/8 inch X length of steel. and I plan to hold it back with ash gap, which will further reduce the thermal transfer.

Chip