Heating mantle conversion

I have this heating mantle that wasn't working properly, so tested it and noticed it wasn't getting up to temp or pulling the rated wattage at the wall outlet.

I popped the front cover off it and found the controller inside rated fro 220-250vac despite the plug attached being a US standard 3 prong. See photo.

Anyway, so I was reading through the forum here and seems i may be able to work around this issue and get the mantle working properly if I can find a suitable replacement for the controller. I saw some posts regarding 1000 watt dimmers but for some reason those dimmers are super expensive here in Canada. Like anywhere from $60-$100 and they are all slider type dimmers , cannot find any rotary ones. I thought the dimmer would be a cheap way to get up and running, but apparently not.

The mantle itself is rated 450 watts and holds 2000ml vessels.
http://www.ebay.ca/itm/110-V-2000-ML-Capacity-Heating-Mantle...
(of course it is not actually a 110vac as evident from the controller)
Anyone have any other suggestions?

Quote: Originally posted by wg48

I suggest you bypass the controller by connecting the mantle directly to the main supply then check to see if it uses the rated 450W say between 400W to 500W. If its a round 113W the problem is the mantle is designed to operate on 220V (assuming it is a 450W mantle). Note if the mantle is designed for 220V replacing the controller with a 110V one will not make it consumer the 450W. If with the 220V controller switched to maximum, it only consumes a round 113W, that strongly suggests it is a 220V mantle.

Quote: Originally posted by Sulaiman

is this what you are looking for ? http://www.ebay.ca/itm/2000W-220V-AC-SCR-Electric-Voltage-Re... or in an enclosure http://www.ebay.ca/itm/AC-110V-220V-SCR-Voltage-Regulator-ad...

Quote: Originally posted by burnteloi

Not following you sorry, the unit when plugged into a 110v outlet draws 195 watts regardless of knob position. The mantle itself is simply a heating element wrapped in fibreglass webbing and connected to the controller, like a hotplate. I was actually thinking of buy a $20 cheapo hotplate and gutting it. Not sure if you were actually suggesting I plug the element directly into a 110vac source, but um that doesnt seem like a great idea.

Quote: Originally posted by Praxichys

Just use a multimeter and check the resistance of the element. That will tell you exactly what it will draw at 110V, no need to plug it in directly.

Quote: Originally posted by burnteloi

Quote: Originally posted by Praxichys   Just use a multimeter and check the resistance of the element. That will tell you exactly what it will draw at 110V, no need to plug it in directly. I had an extra new element and just tested the resistance, came up as 138-140 ohms. I plugged the black into the com port on the multimeter and the red to the volt/ohm/amp, switched the dial to ohms and probed each end of the wire element. It has been awhile but I think I got it right:-) The element itself on its packaging is rated 450watts, but provides no other specs. As for the math...dunno, looks like 110v 13a 140ohm 1430 watts.?? [Edited on 14-2-2017 by burnteloi] [Edited on 14-2-2017 by burnteloi]

burnteloi

there are inconsistencies in your data;

if the resistance is 139 Ohms then using 110 V you should measure 87W
(110x110)/139 = 87 .... wg48 has a faulty calculator

120 Vac would give 103.6W

for 139 Ohms drawing 195W the voltage would need to be 164 Vac

not to worry, the figures give a ballpark guestimate .....
250 Vac would give 450W into a 139 Ohm load.

So unfortunately I suspect that you have a 240 Vac 450W 'nominal' element.

87W for a 2l flask is going to need lots of insulation and patience

The controller that I pointed to, and you bought, should cover WARM to SIMMER ... sorry , not

I had a quick look at the 110:220 adapter pointed to by JJay
I suspect that they are 50W (in an Antarctic wind tunnel, based on most cheap-Chinese specifications)
so not useful here.

There is a 'trick' to multiply the power using diodes and capacitors but I would not do that in this case.

Unfortunately you need a 500 VA, 220-240 Vac supply (transformer)
or a different element, or mantle,
or, as above, insulation and patience.

P.S. ... regarding insulation and patience ... since vapourising water requires 2257 kJ kg^-1,
https://en.wikipedia.org/wiki/Enthalpy_of_vaporization
with perfect heat insulation, 87W would vapourise 1l of water in 7.2 hours

[Edited on 14-2-2017 by Sulaiman]

I think that the adapters are designed for 50W when coverting to/from 110/220 Vac
but when just passing-through the power without changing the voltage, just the plug or socket gemetry, then 13A can pass
I read specifications with a cynical eye


P.S. I also consider things another way, heat.
With no ventilation, I doubt that more than about 5W could be dissipated by the enclosures before serious internal heating occurs,
and good commercial inverters are 90% efficient,
so 50W is about right, to me.
OR, at 240V x 13A output, 5W dissipation requires a 99.84% efficient inverter, unlikely to be anywhere near that.

[Edited on 14-2-2017 by Sulaiman]

Quote: Originally posted by JJay

Hmm... similar ones say that they can handle 13 amps... I don't really see any reason to believe that they are 50 watts....

[rquote=474664&tid=72284&author=Sulaiman


(110x110)/139 = 87 .... wg48 has a faulty calculator


[/rquote]

Apparently yes lol

Quote: Originally posted by wg48

Quote: Originally posted by JJay   Hmm... similar ones say that they can handle 13 amps... I don't really see any reason to believe that they are 50 watts.... Given the size and cost its probably just an adapter for connecting various plugs to various sockets. I strongly doubt it converts between 110V to 220V or 220V to 110V certainly not at 13A. Its too small and too cheap.

Quote: Originally posted by JJay

Quote: Originally posted by wg48   Quote: Originally posted by JJay   Hmm... similar ones say that they can handle 13 amps... I don't really see any reason to believe that they are 50 watts.... Given the size and cost its probably just an adapter for connecting various plugs to various sockets. I strongly doubt it converts between 110V to 220V or 220V to 110V certainly not at 13A. Its too small and too cheap. Right, but with one of those, he could plug his stirrer into a 220V outlet without modifying anything. Most U.S. households do have 220V current... it's just that they usually only use it for major appliances.

"Now if I increase that current variable to 4 amps I get about 440 watts which would be the elements rating. I am obviously missing something in regards to current. "

how would you increase the current to 4A ?

it could be by increasing the voltage by a ratio of 4 : 0.78571
so 110 x 4/0.78571 = 560V
your mantle would now be dissipating 560V x 4A = 2.2 kW
OR
you need to reduce the resistance.

If you have no alternative, then you may be able to modify your mantle element .......

IF you could connect a heat resistant wire half-way along the heating element, and connect that to Neutral (White),
connecting one end of the element to 110 Vac (Black) would heat half of the element with
Power = (110 x 110) / (139/2) .... (half of the resistance)
Power = 174W in one half of the element
If you now connect the other end to 110 Vac also, you get 348 W.

Basically you are putting 110 Vac across each half of the element which is equivalent to 220 Vac across the original element.

I have not tried this, I do not know how difficult it is to safely and reliably connect to the middle of the element,
but in theory it works

P.S. if you are off a little, say 60% and 40% along the element instead of 50:50, I think that would be OK
You should be able to 'probe' through the insulation with a needle to find the near-mid-point.

[Edited on 14-2-2017 by Sulaiman]

[Edited on 14-2-2017 by Sulaiman]

the one that he ordered is a phase-controlled triac 'dimmer'
it gives very steady heating.

A simple power controller like these gives a more constant boil-up rate than a mantle (or even an oil bath) with a PID controller
unless the PID is very well tuned and/or there are changes in the environment during operation.

EDIT: As of this morning's post, I now have three of these controllers,
one for my 1.5 kW 240 Vac hotplate, which works very well
(so far with this controller I have only done 6x 1.4 litre EtOH distillations, not at full power ... time will tell),
one for my in-progress diy 250 W mantle/stirrer, (still looking for 500ml-mantle-sized tin cans)
and now one for spare (they are cheap-Chinese)

P.S. I just realised, JJay is warning about any future purchase of a mantle, I think ... D'oh!

[Edited on 14-2-2017 by Sulaiman]

[Edited on 14-2-2017 by Sulaiman]

Quote: Originally posted by Sulaiman

P.S. I just realised, JJay is warning about any future purchase of a mantle, I think ... D'oh! [Edited on 14-2-2017 by Sulaiman] [Edited on 14-2-2017 by Sulaiman]

Quote: Originally posted by burnteloi

I am thinking my best best is to go back to plan A and just buy a cheap hotplate, gut it and mod it into the mantle housing. Not really elegant, but cheap and acceptably safe.

I can think of two options that might work.

Typical 110v houses are wired with a 220v split-phase connection. From the pole there is a "neutral" wire and two "hot" wires, each hot being about 120 Vrms above ground, but 180° out of phase with each other. Thus, you get 110V for appliances and such by connecting them across neutral and one of the phases, and the 220V appliances are simply connected across both phases, so the appliance gets + and - 110V for a total of 220V.

That said, if your house is fed with split-phase (and they most often are) you can run an extension cord from a 110V outlet connected to the A side of the panel to an outlet connected to the B side of the panel. Make a cheater cord to skip the neutral connections and instead wire both hots (and for Pete's sake, the safety ground) to the mantle. This will feed it 220V and it will operate as designed.

Alternatively, you can try to put a tap in the resistance wire within the mantle itself. If you connect to the heating element exactly halfway down its length (you can check where you are by measuring resistance, no need to disassemble), you can connect your tap to one side of the heating controller and both the original connections to the other side of the heating controller, effectively splitting one element into two parallel elements, thus halving the resistance and therefore doubling the wattage. It will then run at 110V with the same power as it was designed for at 220V.

EDIT: Whoops, Sulaiman has suggested idea #2 already.





To find whether you have both an A and a B side socket, use the multimeter and measure the voltage across both hots. If you're on the same side, it will show 0V, and if you have opposite sides, it will show 220V.

[Edited on 14-2-2017 by Praxichys]