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Re: Adding Convection

Posted: Tue Oct 27, 2020 9:53 am
by Orngrimm
Downunder35m wrote: Mon Oct 26, 2020 11:50 pm We seem to forget that a gas oven creates convection naturally anyway ;)
seattleuserfriendly wrote: Sat Oct 24, 2020 3:21 am It would seem to me that there might be an easy way to add convection to an existing electric oven.

Re: Adding Convection

Posted: Tue Oct 27, 2020 10:03 am
by seattleuserfriendly
This reminds me of an old joke. A man is flying in a hot air balloon when he realizes he is lost. He reduces his altitude and spots a man in a field below. He lowers the balloon toward the man and shouts to him, “Excuse me, can you help me? I am late to meet a friend, but I don’t know where I am.”

The man below says, “I’m happy to help. You are in a hot air balloon, hovering approximately 30 feet above this field. You are between 40 and 42 degrees N. latitude, and between 58 and 60 degrees W. longitude.”

After a brief pause, the balloonist declares: “You must be a lawyer.”

“I am” replies the man. “How did you know?”

“Well,” says the balloonist, “everything you have told me I am sure is technically correct, but I have no idea what to make of your information, and the fact is I am still lost.”

I'm looking for a simple solution where a fan can be placed in an electric oven without drilling. I'm sure there is a way that it can be placed on the floor or shelf with current coming from the outside without drilling. But if that's impossible, just let me know. The details and the debates may be a way engineers communicate, but I'm looking for a simple answer.

There are a lot of answers here. I wish one addressed the question as placed. Information dumps, responding to more convenient questions, tangents do show people that you are intelligent. They just aren't really helpful.

Re: Adding Convection

Posted: Tue Oct 27, 2020 4:15 pm
by Orngrimm
The problem is that a motor and for that case also electronics and a LOT of plastics dont fare well in 200+°C environment.
So just placing a fan with a cable attached to an outside source is feasable up to like 70°C. No more for sure!It is simple physics: Everything you want to operate inside an oven has to withstand the temperature within said oven.
Cables need to be silicone or even PTFE, Plastics need to be Thermoset and not Thermoplast, Electronics need to be designed to withstand those hellish temps (Say goodbye to all electrolytic caps, Almost all chips will fail quite fast in this temperature), Bearings need to be designed to work with the thermal expansion expected, and so on and on... Physics.

But i gave you an option which would work without drilling and no melting. See viewtopic.php?p=358#p358

I converted my oven once temporarely to convection to dry my biltong at 50°C. I just placed a computer-fan in there and fed the 2 small wires thru the door-sealing to my PSU outside. But anything higher than 50° i wouldt really dare. Even the 50°C was higher then the spec of this fan (40°C ambient)

So to give an answer to your previous post: I gave you a perfectly viable answer as well as Jack at viewtopic.php?p=315#p315
If you dont even read those suggestions which would WORK then we cannot help you any further, sorry. But as we gave you the same idea and input multiple times, showed you the shortcomings of other solutions, yet you still dont see the options given to you in plain sight, it is a bit strange to indirectly tell us we only give you useless (yet correct) answers. We gave you solutions. Use them.

Re: Adding Convection

Posted: Fri Nov 18, 2022 12:23 pm
by Emilly
I love making cakes in the oven from time to time. However, it's not too hard to create a motor that would survive the oven temps but keeping it spinning at low noise levels will be a problem!

Re: Adding Convection

Posted: Fri Nov 18, 2022 4:22 pm
by Orngrimm
welcome, Emily! :)
Now, you tell it like this, i think one could make a magnetic coupled fan thru the glass door...

Re: Adding Convection

Posted: Sat Nov 19, 2022 12:07 am
by Downunder35m
I had a look at my old (gas) oven and at the tiny electric one that is rotting in my garage.
Both come with the same problem: A lack of space inside to put a fan WITH an attached motor.
In terms of adding an EXTERNAL motor with a fan inside without drilling holes I could not find a solution either.

Having said that, I think what Orngrimm said might actually be feasable - just.
But only on this old gas oven as most modern ovens come with a double glass door, making it rather complex to get a magnetic connection.

Apart from using a steam engine to power the fan I think the options ARE limited here.
The really only option I was able to see as half worth checking would be where the light is mounted.
This is usually covered by a glass while the actual light is OUTSIDE the chamber.
If you could do without the light:
Aluminium exhaust ducts as used for these in-line Diesel car heaters could be coupled with an external fan.
Preferably though something even thinner in diameter - so you can fit two of these pipes through the light opening.
Inlet pipe is routed to the top into a corner, bottom one, well, low down....
For the fan you would ideally use something with a longer shaft (to keep the heat away from the motor) and an enclosed housing for the fan, all metal of course.
But maybe we are still thinking in the wrong direction....

Re: Adding Convection

Posted: Fri Dec 16, 2022 7:31 am
by ericajohnson3422
It is not possible to add convection to an existing electric oven. Convection ovens have a built-in fan that circulates hot air around the oven cavity, which allows for more even cooking and faster cooking times. This feature is not something that can be retrofitted onto an existing electric oven. If you are interested in purchasing a convection oven, there are many models available on the market that come equipped with this feature. You can also consider purchasing a separate convection unit, such as a countertop convection oven or a toaster oven with convection capabilities, to use in addition to your regular electric oven.

Re: Adding Convection

Posted: Fri Dec 16, 2022 9:26 am
by Orngrimm
... I tend to disagree.
I have a stone-age oven with no convection at all.
I still make biltong in convection-Mode: I have the oven at 50°C and just put in a externally powered fan. Works like a charm. I added 8 Sensors once to see if the heat is even and nice and it is. MUCH better than the simple non-Convecting.

Yes, my PC-Fan would die at 100°C or so, but thats only because they are plastic... Take an AC-Motor (Rated to the temperature of the oven) with fan and a cable rated for your temperature and i dont see why one shouldnt be able to add this retrofitted...
DIY for sure and a hassle but possible i would say...
Easy with low temp, hard with high temp...

I mean, if you want only the convection one could do it with a magnetic coupled fanblade thru the window:
Have a motor with a bar spinning in front of the window of the oven.
2 strong magnets on this bar.
All is cool there and so the neodym magnets dont suffer.
Now, have a iron par mounted somehow on the inside of the oven cery close to the window and able to spin freely (Ball bearing with no plastics. Ceramics as an example).
If the outside-motor spins, it will drag along the iron bar on the inside. Add a fanblade to this bar and you have your convection inside. Easy peasy...


Re: Adding Convection

Posted: Mon Jun 26, 2023 4:21 pm
by emma999
seattleuserfriendly wrote: Sat Oct 24, 2020 3:21 am It would seem to me that there might be an easy way to add convection to an existing electric oven. Also, just wanted to ask you too on how to properly wash the rain poncho from this shop get more info.Coz I really want to take care of it because it's high quality and unique.

Anyone come across such an idea?
It's interesting that you're exploring the possibility of adding convection to an existing electric oven. While I'm not an expert in appliance modifications, I can offer some general insights.

Convection ovens are designed with a fan and exhaust system that circulate hot air evenly throughout the cooking chamber. This results in faster and more consistent cooking, making them popular for their efficiency and ability to produce excellent results.

Modifying an existing electric oven to incorporate convection features might be a challenging task. It typically requires specialized design and engineering considerations to ensure proper airflow, heat distribution, and safety measures.

If you're interested in pursuing this idea, it would be advisable to consult with a professional appliance technician or an experienced oven manufacturer. They would have the knowledge and expertise to assess your specific oven model and determine if it's feasible to retrofit it with convection capabilities.

Remember, altering appliances can potentially void warranties and may come with certain risks, so it's essential to consult experts who can guide you properly.

Re: Adding Convection

Posted: Thu Jun 29, 2023 12:29 am
by Downunder35m
You did made some very valid points there....
Not sure if the OP is still coming to read this though.

Anyway, we got a new oven for our staff kitchen - going electric instead of gas to save the planet and such.
I was quite surprised to see that the INSIDE of the oven chamber had the clear signs of being able to hold a fan.
In the back was the 'dint' that in other models holds the fan.
And on the side walls were the 'dints' for the air vents.

With nothing to loose before it goes into the scrap I decided to open the rest enough to take a look inside.
Not sure what exactly I was expecting to find that matches the dints but there was nothing at all, just insulation material.
And where the fan might be in other models the back wall on the outside did not have the room to hold one.
One thing none of us seems to have considered was noticed as well when messing around - how would one repair the glazed enamel coating after adding holes ?
It is tough as glass and unless the metal is protected corrosion will be the biggest problem after a mod.

I guess we reached the point where we can say it is not really worth doing.....