# 12v heating element to help boil



## snails07 (27/1/17)

So my new 50L kettle was struggling to boil 35L using the Keg King 2200w element. It was boiling but it certainly wasn't a rolling boil and I ended up missing my OG by about 4 points.
I don't want to add another big element that would require using a different power point. But I've found a 12v 600w element on ebay and I am wondering if this would do the trick to give it a boost.
I'd assume this could run off the same powerpoint alongside the main element and a pump?

http://www.ebay.com.au/itm/Aiicioo-Water-Heating-Element-1-INCH-NPT-BSP-Flange-Immersion-Heater-12v-600w-/322197393493


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## MitchD (27/1/17)

No, i'd adjust your expected boil off to meet your actual boil off. Do a "Dry run" boil for an hour noting the pre then post boil volumes and adjust your software to suit.


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## Matplat (27/1/17)

Yeah, I wouldn't bother, I use a 2400w element and the boil isn't crazy, but the beer still tastes good!


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## snails07 (27/1/17)

MitchD said:


> No, i'd adjust your expected boil off to meet your actual boil off. Do a "Dry run" boil for an hour noting the pre then post boil volumes and adjust your software to suit.


Sounds like a much better solution!
My previous setup had a crazy boil so I was sort of disappointed not seeing it with this one.


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## snails07 (27/1/17)

On second thoughts, I think I will add the extra element.

I'd prefer a more vigorous boil and also the time it takes to heat up will be lessened, as it took quite a while to reach boiling.
But can it be run from the same circuit as main element and pump?


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## idzy (27/1/17)

snails07 said:


> On second thoughts, I think I will add the extra element.
> 
> I'd prefer a more vigorous boil and also the time it takes to heat up will be lessened, as it took quite a while to reach boiling.
> But can it be run from the same circuit as main element and pump?


No it can't, assuming it is a 10amp circuit, you would need 20amps.


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## TwoCrows (27/1/17)

Snails07 , You could run two elements. But, you will need too run them of separate breaker circuits. This is common practice if you don't have a 15 amp or higher GPO. 

Hope this helps.


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## ianh (27/1/17)

You will need a transformer to run a 12 volt heater from the Mains which will cost much more than the heater. Why not just get a 500 watt 230 volt heater for about the same price as the 12 volt one.


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## bevan (27/1/17)

You could get one of these and pull the element out and fit it to your pot. Very cheap option that a lot of people use.
https://www.bigw.com.au/product/smart-value-1-7-litre-cordless-plastic-kettle/p/WCC100000000372139/
Note: disclaimer, use a sparky to do it to make sure it's wired up right.

Edit: forgot the link


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## Lyrebird_Cycles (27/1/17)

Another option is to buy two cheap 240V heaters and run them in series. The combination will have a power output around half that of the rating of a single heater*. An additional benefit is the power output per unit area is reduced to one quarter of the rated value so the surface temperature is much reduced thereby avoiding scorching and making them easier to clean.

*As an example: for an experiment I bought two immersion heaters which were about $20 each. They each draw ~9 amps on 240V for about 2200W. In series they draw a little under 5 amps for a total of about 1200W. The difference is expected, the elements will have a small positive temperature coefficient of resistance.


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## snails07 (27/1/17)

Well that's a shame.
I thought because it was 12v, I could just wire it up to an old 12v power plug and away I went.

So the only way to really get more power is to run a second power point that is on a different circuit - is that right?


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## snails07 (27/1/17)

Well that's a shame.
I thought because it was 12v, I could just wire it up to an old 12v power plug and away I went.

So the only way to really get more power is to run a second power point that is on a different circuit - is that right?




Lyrebird_Cycles said:


> Another option is to buy two cheap 240V heaters and run them in series. The combination will have a power output around half that of the rating of a single heater*. An additional benefit is the power output per unit area is reduced to one quarter of the rated value so the surface temperature is much reduced thereby avoiding scorching and making them easier to clean.
> 
> *As an example: for an experiment I bought two immersion heaters which were about $20 each. They each draw ~9 amps on 240V for about 2200W. In series they draw a little under 5 amps for a total of about 1200W. The difference is expected, the elements will have a small positive temperature coefficient of resistance.


This has gone way over my head! Running 2 elements draws half the power?


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## Lyrebird_Cycles (27/1/17)

They are in series. If you run them in parallel they'll draw twice the power.


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## SBOB (27/1/17)

Lyrebird_Cycles said:


> Another option is to buy two cheap 240V heaters and run them in series. The combination will have a power output around half that of the rating of a single heater*. An additional benefit is the power output per unit area is reduced to one quarter of the rated value so the surface temperature is much reduced thereby avoiding scorching and making them easier to clean.
> 
> *As an example: for an experiment I bought two immersion heaters which were about $20 each. They each draw ~9 amps on 240V for about 2200W. In series they draw a little under 5 amps for a total of about 1200W. The difference is expected, the elements will have a small positive temperature coefficient of resistance.



to clarify this:
you're proposing this as a solution for someone who wants a way to cheaply add additional heat without adding a single '10 amp circuits worth' element (eg 2200-2400w)

So, wire up a couple of cheap 240v elements in series, and you're effectively adding a single '~1200W' element, just split across two elements with the added benefit of a lower heating density per element


just so people dont think they magically get more heat for less Amps/Watts


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## Camo6 (27/1/17)

Like mentioned, the easiest thing to do is just bung another element in and run an extension lead to a seperate circuit in your house. Easier still is to use an over-the-side element. Saves you drilling another hole but they cost a bit more than a KK element or similar.


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## Lyrebird_Cycles (27/1/17)

SBOB said:


> to clarify this:
> you're proposing this as a solution for someone who wants a way to cheaply add additional heat without adding a single '10 amp circuits worth' element (eg 2200-2400w)
> 
> So, wire up a couple of cheap 240v elements in series, and you're effectively adding a single '~1200W' element, just split across two elements with the added benefit of a lower heating density per element
> ...


Yep.

To be clear, the units I used have a resistance ~=26 ohms*.

If you run one unit on 240 V it draws 240 / 26 ~= 9 amps, 240V x 9 amps ~= 2200 watts.

If you run two units in series the combined resistance is ~= 52 ohms, 240 / 52 ~= 4.5 Amps. 240V x 4.5 amps ~= 1100 watts.


* this is the resistance at room temperature. I've left the effects of the increase in resistance with temperature out of this explanation for clarity.


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## micka80 (27/1/17)

I would think you have more than 10 amps to play with, I would have to check my switches but pretty sure they are rated for at least 20amps. Each connection for a gpo is 10amp, I use a double gpo with two 2200w Keg King elements and no issues on that circuit, what your pump uses will be the straw on the camels back though. I can give you a amp draw figure tomorrow as I am doing a brew. Go check your meter board and see what your circuits are rated for. A simple Kettle will draw 10amps, so I would be surprised if you were that restricted.


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## Camo6 (27/1/17)

micka80 said:


> I would think you have more than 10 amps to play with, I would have to check my switches but pretty sure they are rated for at least 20amps. Each connection for a gpo is 10amp, I use a double gpo with two 2200w Keg King elements and no issues on that circuit, what your pump uses will be the straw on the camels back though. I can give you a amp draw figure tomorrow as I am doing a brew. Go check your meter board and see what your circuits are rated for. A simple Kettle will draw 10amps, so I would be surprised if you were that restricted.


Depends on the circuit. I assume by switches you're referring to circuit protectors? You might have 20A breakers but I'd be confirming that. Since most power circuits use a 16A breaker you'll likely run into troubles trying to run 19A through them (2200W÷230V×2). What's more, 16A circuit breakers won't trip instantly at 19A of overload current. It could take up to an hour allowing excessive heat to generate in other parts of the circuit. If you're in an older home using old ceramic fuses and/or good old vulcanised india rubber cabling, I'd be making sure my insurance is up to date.
Unless you're certain your circuit is rated for the current draw, spread the load between them.


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## micka80 (28/1/17)

Just checked my current draw and circuit breakers, draws 18 amps and have 20amp breakers. It does seem that the 2.5mm cable we have running through our house is rated for 20amps only. 
I must apologize for giving bad advice, I am getting away with it but I think from a safety point of view, I would not do it, I wonder if the switches are oversized or the cable can handle over 20amps?


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## Camo6 (28/1/17)

micka80 said:


> Just checked my current draw and circuit breakers, draws 18 amps and have 20amp breakers. It does seem that the 2.5mm cable we have running through our house is rated for 20amps only.
> I must apologize for giving bad advice, I am getting away with it but I think from a safety point of view, I would not do it, I wonder if the switches are oversized or the cable can handle over 20amps?


2.5mm2 will handle 20A under most normal domestic conditions. If it was buried in insulation or running through conduit it may not. Nothing wrong with how yours is wired if derating factors were calculated correctly to begin with.


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