Electric hot plate for small table-top still

[Magicbean]

I have been using this as a heater for my 5L copper alembic:

https://www.amazon.co.uk/VonShef-Premiu ... B0140XX8E2

It's cheap (£18) but seems to do the job OK; it had better reviews on Amazon than the other cheap ones.

It does get hot underneath but my standard kitchen laminated worktop seems OK with it; (obviously) make sure that no distillate can spill on the same surface.

When you first use it, the instructions say to run it on maximum heat for a period (15 mins) and that it will burn off the manufacturing solvents etc. inside. I strongly recommend you do this over a heatproof surface and not in your house unless you have a good extractor fan. It's quite alarming the way the smoke rolls out from every hole, behind the heat control knob .... it gets very hot and looks as though it's about to catch fire (but it doesn't). Well... mine didn't, even though I could just about see the hotplate glowing a dull red in patches.

The continuously variable rotary knob without click stops seems quite controllable and the hob is just about strong enough (a bit flimsy but adequate). It keeps my output dripping gently on about power level 3 and runs faster than I need on max. Certainly convenient for a small still as it packs away easily after use.

I was planning to use a heat controller and threaded thermocouple to control it but the walls of the hotplate are too thin to tap; so I haven't bothered and it seems OK without it.

[Bushman]

The continuously variable rotary knob without click stops

For anyone thinking of this as a heat source continuous heat is a must, do not consider one that cycles on and off.

[der wo]

It's thermostate controlled. So it switches on and off all the time. No way to get for this cheap price something without cycling. Only very old used hotplates are perhaps available on ebay which doesn't cycle.
And without sandwich bottom the hotplate will "think" it's very hot inside the pot and shut off very early. All in all it will run very slow.
But it seems to work for the OP. Perhaps because copper is such a good heat conducter? With a ss pot without thick bottom I am relative sure it won't work.

[Bushman]

It's thermostate controlled. So it switches on and off all the time. No way to get for this cheap price something without cycling. Only very old used hotplates are perhaps available on ebay which doesn't cycle.
And without sandwich bottom the hotplate will "think" it's very hot inside the pot and shut off very early. All in all it will run very slow.
But it seems to work for the OP. Perhaps because copper is such a good heat conducter? With a ss pot without thick bottom I am relative sure it won't work.

So there you have it. While reading this post my mind wandered to a retired owner of a restaurant. After retiring he opened a craft distillery in our state and for a heat source he used a gas stainless steel grill and set his 100 gallon still on top of the grill.

[Magicbean]

It's thermostate controlled. So it switches on and off all the time. No way to get for this cheap price something without cycling. Only very old used hotplates are perhaps available on ebay which doesn't cycle.
And without sandwich bottom the hotplate will "think" it's very hot inside the pot and shut off very early. All in all it will run very slow.
But it seems to work for the OP. Perhaps because copper is such a good heat conducter? With a ss pot without thick bottom I am relative sure it won't work.

Yes, it has a sensor. I think the regulation only works well enough because it's in contact with a copper pot containing liquid in.

[der wo]

The switching on and off should produce a little "click"-sound. It's probably easy to hear next run.
1500W is way enough for a 5l still. So even if you only have 1000W in average because of the cycling, it should be fine. And if the output doesn't change much during the run, everything is fine. The only thing is, that you don't know exactly how much wattage you use.

The worst thing you can have with hotplates is a dancing pot. The bottom curves convex during heat up and then the heat isn't transfered right to the pot, and now either the hotplate starts to glow (and the pot starts to dance or roll and you are wasting most of the energy) or the overheat switch shuts it down... I had this problem with a cheap thin walled ss pot. I had to by one with a thicker bottom.

[Magicbean]

The switching on and off should produce a little "click"-sound. It's probably easy to hear next run.

Yes, it does that. I knew it was a on/off cycling one when I bought it but I thought it might work OK and it does (for me).

1500W is way enough for a 5l still. So even if you only have 1000W in average because of the cycling, it should be fine. And if the output doesn't change much during the run, everything is fine. The only thing is, that you don't know exactly how much wattage you use.

Given the heat up time and the power input I think about 40-45% of the energy is transferred to the pot. As the power is on for 10% of the time when it's up to temperature I suspect it's only taking about 150W to keep it hot and delivering about half that into the wash.

The worst thing you can have with hotplates is a dancing pot. The bottom curves convex during heat up and then the heat isn't transfered right to the pot, and now either the hotplate starts to glow (and the pot starts to dance or roll and you are wasting most of the energy) or the overheat switch shuts it down... I had this problem with a cheap thin walled ss pot. I had to by one with a thicker bottom.

I don't seem to have any problems like that.