The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Does an oven like this exist?

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nicodvb's picture
nicodvb

Does an oven like this exist?

The oven of my dreams has

-lower resistence

-turntable

-mid-height fan usable in convection or fan-assisted mode (although this last one is much less exciting)

-eventually a quartz grill

-35-40 liters

Essentially it's a convection oven with a lower resistence. Does a beast like that exist for sale?

davidg618's picture
davidg618

I'm certain I won't have an answer for you even with clarification, but I'm curious and I don't understand most your specifications:

what is oven resistence?

What is mid-height? (I guessed centered in the oven's back wall.)

What is a quartz grill?

I think I know what a liter is, but I don't understand how 35-40 liters relates to an oven.

Please?

David G

 

nicodvb's picture
nicodvb

Hi David. By resistence I mean the heating coil. As you guessed the fan should be centered in the oven's back wall. A quartz grill is a source of infrared rays implemented with a quartz lamp; it's frequently used in microwave ovens to brown the surface of food. 35-40 liters should be the volume of the oven cavity.

 

davidg618's picture
davidg618

Resistance lower than what? I calculate my three elements are:

14.4 ohms, 4000 watts; Broil element (top)

19.2 ohms, 3000 watts; Bake element (bottom)

23 ohms, 25oo watts; Convection element (fan compartment)

If all three operate, on occassion, in convection mode the total current would be near the limit imposed by the circuit breakers, so for 240 volts, (2 phase) 40 amp breakers that can theoretically deliver 9600 watts it appears its operating at its lowest practical resistance.

My oven doesn't have a turntable, but three of the drawer move on ball-bearing, full extension slide-outs. They slide with practically no effort.

I'm assuming the quartz grill is the same technology as quartz space heaters: a high-temperature metallic heater, emitting far infrared, and surrounded by an insulating quartz tube that inhibits convection heat loss? What benefit does a quartz grill bring to a conventionally heated oven?

I'm not used to talking about volume in liters; I'm more comfortable with linear dimensions cubed: Height x Width x Depth. My oven is 6.4 cubic feet (.18 cubic meters).

David G

 

 

nicodvb's picture
nicodvb

David, I used a wrong term. I should have written "bottom heating element". In pure convection ovens there aren't top and bottom heating elements, there's only a heating element behind the fan. It's not an ideal setup when baking bread because the bottom of the loaf doesn't brown as well as the top.

I don't know if quartz grills used in microwave ovens are the same as you wrote. As far as I know they use tungsten and halogen gases to reach extremely high temperatures in very short time. The advantage they bring is a very quick and efficient energy transmission. When I used an oven that simulated convection mode using a fan and a quartz grill (alternating on and off periods) I observed huge and uncomparable oven springs.

davidg618's picture
davidg618

Hi, Nico

I've done a little online reasearch re quartz grills. They are a bit pricey, but I'm going to keep my eye on the technology and variations on designs. Competitiion, brought about by an expired patent will eventually bring the prices down. Thanks for tipping me to the technology. I wasn't familiar with it.

Hope you find your dream oven.

David G

nicodvb's picture
nicodvb

-price apart- is that they desperately need a turntable. They radiate extremely intense energy in tubular form due to how they are built (in cylindrical form). Uhm... now that I think of it ... do you believe that a circular quartz tube located around the oven's back fan (to replace the fan's heating element) would make the best of both worlds? 

davidg618's picture
davidg618

What I learned is:

Quartz is in the names Quartz Grill and Quartz Heater primarily for marketing. There is quartz in both items, but in different forms, and perform different functions. However, both units release primarily infrared radiant heat.

Convection ovens simply stirs the heated air in an effort to make its convected heat delivery homogenious throughout the oven for more even heating, and efficiency. There are convection heated ovens that merely have a fan without a dedicated heating element, relying entirely on the base and top elements as the heat source. (My recently replaced 10 year-old Kenmore Elite had such an oven.)

Quartz Grills are constructed from ceramic plates (Quartz sand is part of the ceramic mix) that are  perforated with many tiny holes, (I suspect the holes are "tuned" to far infrared wavelength). They are heated, often with natural gas or propane, and their heat reradiated (infrared) to crisp, or sear food. 

Quartz Heaters heat source is electrically stimulated gases that are contained  with quartz glass tubing--quartz glass is chosen for its insulting ability. The gas'es heat is transferred essentially entirely by radiation.

I couldn't find any online diagrams that show the construction of a microwave oven's infrared heating element, but I'm guessing it's likely a hybrid of both where in wide spectrum radiant energy from the excited gas is converted to narrowband far infrared in the ceramic grill.

A convection dedicated heater simply adds more heat energy to the oven's air. I believe the oven's air is heated primarily by conduction, i.e., air molecules colliding with the convential heating element. Obviously, because exposed oven heating elements glow red, some heat energy is transferred by radiation, however I think its less than the energy transmitted by conduction. I think it would come down to the efficiency of the various heaters to transport heat by conduction, convection, or radiation that would most influence the choice.

David G