Oven Door? Insulated or not. Pros & Cons

[schallert]

Hello all,

Looking for feedback on insulated door vs a plain steel door like sold on FB?

Any and all thoughts appreciated.

Dan

[Les]

Re: Oven Door? Insulated or not. Pros & Cons

Although the opening is small compared to the whole volume of the dome, you will lose heat. Insulation is your friend. My door 2.5 inches thick and filled with loose vermiculite, and it gets hot on the outside, when the inside temp is up there.

Les...

[david s]

Re: Oven Door? Insulated or not. Pros & Cons

Steel is also a great conductor of heat and will suck heat from the inside to the outside quite readily, so any insulation added to the door should improve the oven efficiency. A steel door is also dangerous to handle when hot.

[Ageo308]

Re: Oven Door? Insulated or not. Pros & Cons

Get some insulating blanket (kaowool etc...) cut it to size of the door and then weld 2 pieces of aluminium (lighter) around it and you will have an insulated door.

[dmun]

Re: Oven Door? Insulated or not. Pros & Cons

It all depends on what you want your door for. If you want your oven to be hot enough to cook the day after the fire, you need a well insulated door. For ordinary retained heat cooking a piece of plywood does fine by me. Remember: your heat is retained in the brick dome, only a little in the air inside.

[lwalper]

Re: Oven Door? Insulated or not. Pros & Cons

My build is a bit more utilitarian than some of these beautiful ovens I've seen here. What just struck me was, is there a prefab insulated door, on hinges, for ceramic kilns? It seems like I've seen, somewhere, a door about 2 inches thick, which would close securely, with a latch? I'm really just looking for something to close the hole. My wife will be the one using the oven and is concerned about having to physically lift and place a heavy, insulated plug in the hot opening.

Or, how about putting wheels on the bottom of the door so it will just roll to the side without having to lift it? A little ceramic rope around the inner edge would compress slightly giving a good closure. There should not be much heat on the outside of the door so even some small rubber wheels would work?

[RTflorida]

Re: Oven Door? Insulated or not. Pros & Cons

An insulated door does not have to be a "heavy plug" as you mention.
I made both - a heavy steel door (1/4" boiler plate, solid steel handles, and heavy steel support legs) and a lightweight insulated plug (sheet aluminum over a frame of aluminum angle "iron", then filled with perlite, with aluminum handles). Both were painted black with high heat paint 3 yrs ago and still look great. Since I have no welder of any kind, both are assembed with stainless screws or bolts.
The steel door looks great, rugged, heavy duty.....but it weights 15 lbs, I have chipped so many bricks I've lost count.
The insulated door only weights 4 lbs 2 oz. and is self supporting and does not need legs. (2 1/2" thick).

I think your wife could easily handle a 4 lb door....based on feel, I thought it was only 2-3 lbs....put it on a scale to confirm. Really works well in comparison to the steel, if you are looking to retain heat for a long period.

RT

[david s]

Re: Oven Door? Insulated or not. Pros & Cons

Hinged doors on kilns are usually the fist thing to fail as the kiln ages. They just don't give a positive seal when old and the steel usually rusts badly due to the heat. The bigger the oven the bigger and heavier the door.

[Stan]

Re: Oven Door? Insulated or not. Pros & Cons

I've wondered about door insulation myself. I have a Primavera oven with a steel door. No matter how long or how hot I fire the thing, I CANNOT cook with retained heat the next day. I know the insulation in the oven is working, and all I can figure is that I'm losing massive amounts of heat out of the steel door via conduction. We're talking a 900+ degree oven dropping to 150 in 12 hours. I'm going to do some door insulating experiments this summer and see what kind of improvement I get. I was thinking of just sawing some FB insulation board to size and sandwiching it between the original steel door and a piece of cut aluminum.

Stan

[RTflorida]

Re: Oven Door? Insulated or not. Pros & Cons

Stan,
Thats quite a drop in 12 hrs. If I put my steel door in place shortly after pizza (say, 8-9 pm), at 10-11 am the next morning I will be somewhere in the 350 degree range.

With the insulated door and the same scenario, the oven will be at 450-475 the next morning.
Just curious, how much insulation does a Primavera have?

RT

[Stan]

Re: Oven Door? Insulated or not. Pros & Cons

RT,

I'm not sure how much insulation it has. I know it's those high density FB blankets, and I know the outside of the oven gets warm but never hot. The door, on the other hand, reads around 400+ degrees sometimes.

Stan

[david s]

Re: Oven Door? Insulated or not. Pros & Cons

Check out the kind of fiber in the FB board. You don't want nasties floating around there, or you can encapsulate the board completely.

[dmun]

Re: Oven Door? Insulated or not. Pros & Cons

I think the quick cool-down time on the primavera is a matter of mass. It's small in diameter, and may have half a ton less heat-sink material surrounding the chamber than some of our 4 1/2 inch thick pompeiis.

[lwalper]

Re: Oven Door? Insulated or not. Pros & Cons

I've seen a couple of doors fabricated from expanded steel (or aluminum?) formed into a bit of a cage sort of thing to fit the opening, stuffed with hi-temp insulation. Seems like that combo would weigh very little (maybe in the 3-4 pound range) and be durable. I'm insulating the oven with 8# FiberFRAX blanket and am certain I'll have enough "left over" to build a door. I'll just need to plan on that feature when I develop the entry opening to give myself something flat to seat and seal to. Initially I was thinking about a flush mounted door stuck to the face of the oven, but, I'm not really stuck on any one design so things change from day to day.

[Stan]

Re: Oven Door? Insulated or not. Pros & Cons

dmun,

I'm not sure that it's only a matter of mass, but I admit that mass matters.

I had a large party last week with the oven at pizza temp (900+) for well over 3 hours. The outside of the oven was warm to the touch for around an hour while the inside was screaming along. The next morning, probably 13 hours later, I was at 250 with the door on. There's no way the masonry wasn't completely saturated with heat, and to my eyes the Primavera's walls and floor are just as thick as the FB Casa.

I would think that fully saturating any amount of masonry, regardless of oven size, would result in that heat being radiated back at a consistent rate. If I'm not losing heat through the insulation layer, and my IR says I'm probably not, what else is left but the door? My insulation will be the ambient outdoor temp while my door is over 500 degrees. That heat's gotta go somewhere. To me, the door seems like the weak point in the system.

Or, I'm completely out to lunch...
Stan