Author Topic: Reducing heat loss when opening door  (Read 3538 times)

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Offline Oberon

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Reducing heat loss when opening door
« on: August 04, 2009, 01:01:08 PM »
Greetings all,

So if you cook at high heat in a conventional home oven you know the woosh of searing heat that rushes out when you open the oven door.  Also, notice how brick ovens commonly oven space ABOVE the top of the oven door...hmmm...so I am thinking about (and just starting to devise some plans for) creating a 'heat dam' or a lip across the top of the front of the oven interior, speculating that it might prevent at least some of the hot air at the top of the oven rushing out when opening the door.

Has this been addressed before (please point me to the thread)?  Anyone try something like this out?  Recommendations?

Thanks much...


Offline pacoast

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Re: Reducing heat loss when opening door
« Reply #1 on: August 04, 2009, 06:58:11 PM »
It's a good idea & while it won't be a panacea, it should help. It is important for both heat retention and drafting in brick ovens. Heat rises, with the hottest air typically being at the top (dome) of the oven. So if you build the "heat dam", not only is your effective door size reduced but you are mostly losing the (somewhat) cooler air at the bottom of the oven.

A conventional home oven doesn't have the thermal mass to make to achieve the thermal dampening seen in brick ovens, so the effect won't be as large. But at a guess I'd say it's significant enough to be worthwhile. Don't let your dam interfere with the door gasket though or you will probably negate the improvement.

.

Offline Oberon

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Re: Reducing heat loss when opening door
« Reply #2 on: August 04, 2009, 07:14:52 PM »
Nice feedback on the rationale...and thanks for reminding me of the concept of "effective door size" - I'd forgotten that since I haven't read "The Breadbuilders" in a while...

Now about the design...I'm think pretty cheap and low-tech at the moment: using very heavy gauge wire (no coating) to build a frame that fits inside the perimeter of the top/front of the oven, and that fits tightly enough to remain in place when set (or else I'll rest it on one of the racks in the top slot), then I would use good old foil to wrap around that frame and fit it in place.

Other thoughts?
« Last Edit: August 04, 2009, 07:54:48 PM by Oberon »

Offline pacoast

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Re: Reducing heat loss when opening door
« Reply #3 on: August 04, 2009, 07:42:13 PM »
If it were me, I'd just take a piece of sheet metal and install it with clips, so that it's removable. Or possibly with a hinge if there isn't a broiler element on the roof of the oven to interfere. If you have access to a mil or university surplus store, you might be able to get a metal curtain that slides up & down. Lots of ways to implement an idea like this.

.

Offline Jack

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Re: Reducing heat loss when opening door
« Reply #4 on: August 05, 2009, 04:10:03 PM »
How about just using more oven mass to speed up the temperature recovery?  I use two Fibrament stones in the oven when I need to cook more than three pies in quick succession.

Jack

Offline ThunderStik

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Re: Reducing heat loss when opening door
« Reply #5 on: August 05, 2009, 06:10:03 PM »
Jack has the right idea. I dont think any sheild or anything like that will hgelp the cause. I throw in a big cast iron skillet and another stone.
I KNOW MORE ABOUT PIZZA THAN ANYBODY!!!!!!!

(in my house)

Offline Oberon

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Re: Reducing heat loss when opening door
« Reply #6 on: August 06, 2009, 01:57:35 PM »
I actually like to sheet metal option and will borrow my friends tin snips soon.

I tried a foil wrapped around the front of a rack on the top level and fitted around the opening last night.  I didn't have the capacity to track the temp, and didn't notice much difference in cooking, but I didn't get the same blast of hot air coming out when I opened the door.

Offline ThunderStik

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Re: Reducing heat loss when opening door
« Reply #7 on: August 06, 2009, 03:47:34 PM »
If you are trying to hold the heat in its not going to happen. If you are trying to divert it from your face then that is possible with a sheild of some type.
I KNOW MORE ABOUT PIZZA THAN ANYBODY!!!!!!!

(in my house)

Offline barryvabeach

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Re: Reducing heat loss when opening door
« Reply #8 on: March 14, 2011, 08:58:30 PM »
I didn't want to start a new post, since this is right on topic

So I had a similar idea, and have tried it twice, though due to technical difficulties, I don't have all the data yet.  I am using a regular home oven, on bake at 550, and put the stone on the top rack.  I used a sheet of aluminum foil and wrapped it around the supports for the racks ( I have separate metal supports that the racks ride in, it isn't just a ridge like on many ovens ) and wrapped it so that I covered the part of the oven below the stone. The stone is rectangular and just fits front to back, and has several inches clearance on each side. After heating the oven to 550,  I opened the door 2/3 way to simulate loading a pizza, and then closed the door 15 seconds later.  I have a temperature probe for a multimeter, and it showed a 100 degree drop in the area  adjacent to the stone as soon as the door was closed, but it regained to 525 in 10 to 20 seconds. My assumption was that without the aluminum foil, most of the air would have reached the 450 level and it would have taken a few minutes to restore that. I was cooking 2 pies and I decided to take a second set of measurements after the second pie, then take off the foil, and repeat the test to see how long it would take to recover -  unfortunately, the second pie had a blowout on the stone, and the only way I can get it off was to pull the tray out so I messed up the temps, but will try again this weekend.