Heating element confusion

[8086]

Hi all

I've got one of these ovens as a 'base' for some hackery. http://www.comparestoreprices.co.uk/mini-ovens/logik-l25mov10.asp

I've opened it up and while I was expecting to find the four heating elements wired in parallel, they are actually wired in two series pairs. They're forming a voltage divider and I can measure 120V across each individual element.

I've measured one of the elements resistance (disconnected) and I'm getting about 41ohms.

What I am wondering is if I am able to rewire these to be in parallel, so 240V across each one, instead of across two. I don't really usually 'do' high power stuff so I'm really at a bit of a loss as to whether that would work and result in faster heating or whether it would simply blow the element...

[Lurch]

What I am wondering is if I am able to rewire these to be in parallel, so 240V across each one, instead of across two. I don't really usually 'do' high power stuff so I'm really at a bit of a loss as to whether that would work and result in faster heating or whether it would simply blow the element...

So just to recap, you want to put 230V across a 115v rated element, and you're asking how? I think the main question has to be why? Either use them in pairs or run the whole device from a 110V source. There is going to be a lot of wasted energy somewhere.

[8086]

What I am wondering is if I am able to rewire these to be in parallel, so 240V across each one, instead of across two. I don't really usually 'do' high power stuff so I'm really at a bit of a loss as to whether that would work and result in faster heating or whether it would simply blow the element...

So just to recap, you want to put 230V across a 115v rated element, and you're asking how? I think the main question has to be why? Either use them in pairs or run the whole device from a 110V source. There is going to be a lot of wasted energy somewhere.

Not asking how.

Why? For faster heating. I don't even know that it's a 115V rated element. I don't gain anything by using a 110V source since it would be exactly the same having 4 parallel elements @110V as it would be having 2 pairs of series elements @ 220V.

My question is essentially whether elements like these will withstand double voltage or if they will simply fail. And if they will withstand it, whether doubling the voltage will actually result in higher heat output.

[calexanian]

No. They will not survive double voltage. That will be 4 times the power dissipation. They will heat and crack very fast.

[8086]

Right, thanks.

Time for plan B then - more elements!

Cheers.

[Lurch]

Why? For faster heating. I don't even know that it's a 115V rated element.

Then how would anyone else?

I don't gain anything by using a 110V source since it would be exactly the same having 4 parallel elements @110V as it would be having 2 pairs of series elements @ 220V.

Exactly, you can see why I was confused.

My question is essentially whether elements like these will withstand double voltage or if they will simply fail. And if they will withstand it, whether doubling the voltage will actually result in higher heat output.

Er, no. Probably best you stay away from the mains.

What are you actually trying to do?

[8086]

Then how would anyone else?

I never suggested they would. Like I said, I don't usually deal with heaters so for all I knew it might be possible to run them at double voltage.

Exactly, you can see why I was confused.

Well, I just repeated what I said in my first post, really.

Er, no. Probably best you stay away from the mains.

What are you actually trying to do?

I appreciate the concern, granted there are many people who shouldn't mess with mains, but I think you'll find I said I don't usually deal with high power heaters, not that I don't deal with the mains.

I'm trying to get some extra performance from this oven. I've measured the temperature rate of change and I want to improve it. So I've got two options, more elements (which was my original plan) or run the elements that exist already at higher voltage. I figured it was worth asking since it would save me some money, but if it's not going to work I'm okay with that.

[Lurch]

I'm trying to get some extra performance from this oven. I've measured the temperature rate of change and I want to improve it. So I've got two options, more elements (which was my original plan) or run the elements that exist already at higher voltage. I figured it was worth asking since it would save me some money, but if it's not going to work I'm okay with that.

If you do add more elements you may want to make sure that they are only on for the warm up period. Cheap electronics are usually built with little additional overheads for heat dissipation etc...

[DakLak]

How about a single diode in the supply line so the voltage is reduced by approximately half?

OR you could get a 0-110-220 transformer OR a travel adapter for hair dryers?

[nuhamind2]

I thought it's just a matter of power rating, like resistor you can put any voltage as long the power dissipated less than it's maximum power rating.

Each element of your oven dissipated 120^2/41 = 351 watt if you put 240 on it it will dissipated four times of power whether your element can withstand that power I don't know.

[nuhamind2]

If you do add more elements you may want to make sure that they are only on for the warm up period. Cheap electronics are usually built with little additional overheads for heat dissipation etc...

I doubt it even have any electronic inside

[Lurch]

I doubt it even have any electronic inside

By electronics, I mean cheap electrical goods.