EEVblog Electronics Community Forum

General => General Chat => Topic started by: rvalente on March 24, 2020, 01:03:06 am

Title: Modify a gas oven to add convection fan fuctionality
Post by: rvalente on March 24, 2020, 01:03:06 am
Hello Mates,

among other things, I like cooking, convection ovens are pretty rare here, only used they once and found amazing.

I would like to mod my gas oven (natural gas) do add this functionality. Is just a fan in a chamber? How the bearing and shaft are assembled?

Anyone has seen a hack like this?

Here a patent: https://patentimages.storage.googleapis.com/82/24/a7/3a4d727ab88255/US6615819.pdf (https://patentimages.storage.googleapis.com/82/24/a7/3a4d727ab88255/US6615819.pdf)

Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: floobydust on March 24, 2020, 01:55:16 am
Are you sure you want to do this?
If the fan snuffs out the flame, you don't want the gas staying on or kaboom will happen.
If the fan is on before the burner is lit, it may never light up and kaboom will happen.

You have to make sure your burner and controller can deal with a flame out, that there is flame detection sensor in the oven. Electronic controllers have this safety built in.

Convection oven fan I think is an ordinary shaded-pole motor with high temperature oil in the bearings, and a long shaft with a second (inside) fan for the motor. They get pretty hot.

The patent says the fan in a convection gas oven causes carbon monoxide to spike until the oven metal is warmed up, after several minutes.
Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: Zero999 on March 24, 2020, 12:11:09 pm
A modern gas oven which complies with all of the relevant safety standards will have a flame out sensor, which cuts off the gas.

If you modify it and it blows your house up, then your insurance won't cover you and the police will come after you, if anyone is killed or injured.
Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: rvalente on March 24, 2020, 12:48:24 pm
The oven is equipped with the shut-off valve, I could also add myselft a thermocoupler and an additional NC solenoid valve.

Even the CO and methane levels can be monitored, although I don't think is necessary, my kitchen is very well ventilated.

I'm thinking about the motor and shaft, how to handle such a high temperature and, how big is this propeller?
Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: Ampera on March 24, 2020, 12:50:53 pm
Buy an air fryer. Same concept, but it won't asphyxiate you.
Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: rvalente on March 24, 2020, 12:54:44 pm
Buy an air fryer. Same concept, but it won't asphyxiate you.

I can't bake a nice cake in air fryer :(
Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: floobydust on March 24, 2020, 09:48:00 pm
Search for images "convection oven fan motor".  Note there are two sets of fan blades. You could use a light dimmer to vary the speed.
I wasn't sure what a gas oven in Brazil is like, if they have electronic controls or not.
Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: NiHaoMike on March 24, 2020, 10:12:41 pm
I wonder if by using a high speed BLDC motor the blades and shaft can be made smaller thus reducing the heat lost.
Title: Re: Modify a gas oven to add convection fan fuctionality
Post by: rvalente on March 24, 2020, 11:18:21 pm
Search for images "convection oven fan motor".  Note there are two sets of fan blades. You could use a light dimmer to vary the speed.
I wasn't sure what a gas oven in Brazil is like, if they have electronic controls or not.

Yes, since 2006 its mandatory to all ovens to have this safety valve, to light up the oven you turn the knob and keep it press, push the igniter button and let the flame go on, them you need to hold the knob on for 5 to 10s. There is a thermocoupler over the burner which keeps an very small electromagnetic pilot valve open, if the flame extinguishes the valve will cut the gas flow.

The fan is just a shadded pole with a heat shield, thats all? Hum, easier them tought.