Heating element confusion - Page 1
Forum section: electronics / projects

author: 8086
author_rank: Super Contributor
timestamp: January 04, 2014, 05:21:23 pm
content: Hi allI've got one of these ovens as a 'base' for some hackery.http://www.comparestoreprices.co.uk/mini-ovens/logik-l25mov10.aspI'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...

author: Unknown
author_rank: Unknown
timestamp: January 04, 2014, 05:35:51 pm
content: Quote from: 8086 on January 04, 2014, 05:21:23 pmSo 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.

author: 8086
author_rank: Super Contributor
timestamp: January 04, 2014, 05:39:41 pm
content: Quote from: Lurch on January 04, 2014, 05:35:51 pmNot 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.

author: calexanian
author_rank: Super Contributor
timestamp: January 04, 2014, 05:46:33 pm
content: No. They will not survive double voltage. That will be 4 times the power dissipation. They will heat and crack very fast.

author: 8086
author_rank: Super Contributor
timestamp: January 04, 2014, 05:48:41 pm
content: Right, thanks.Time for plan B then - more elements!Cheers.

author: Unknown
author_rank: Unknown
timestamp: January 04, 2014, 05:49:16 pm
content: Quote from: 8086 on January 04, 2014, 05:39:41 pmThen how would anyone else?Quote from: 8086 on January 04, 2014, 05:39:41 pmExactly, you can see why I was confused.Quote from: 8086 on January 04, 2014, 05:39:41 pmEr, no. Probably best you stay away from the mains.What are you actually trying to do?

author: 8086
author_rank: Super Contributor
timestamp: January 04, 2014, 05:56:56 pm
content: Quote from: Lurch on January 04, 2014, 05:49:16 pmI 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.QuoteWell, I just repeated what I said in my first post, really.QuoteI 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.

author: Unknown
author_rank: Unknown
timestamp: January 04, 2014, 05:59:28 pm
content: Quote from: 8086 on January 04, 2014, 05:56:56 pmIf 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...

author: DakLak
author_rank: Contributor
timestamp: January 07, 2014, 06:07:30 am
content: How about a single diode in the supply line so the voltage is reduced by approximately half?OR you could get a0-110-220 transformerOR atravel adapter for hair dryers?

author: nuhamind2
author_rank: Regular Contributor
timestamp: January 07, 2014, 10:20:38 am
content: 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.

author: nuhamind2
author_rank: Regular Contributor
timestamp: January 07, 2014, 10:27:02 am
content: Quote from: Lurch on January 04, 2014, 05:59:28 pmI doubt it even have any electronic inside

author: Unknown
author_rank: Unknown
timestamp: January 07, 2014, 05:04:54 pm
content: Quote from: nuhamind2 on January 07, 2014, 10:27:02 amBy electronics, I mean cheap electrical goods.