Sciencemadness Discussion Board

Are hotplate stirrers unreliable?

Chemgineer - 15-7-2022 at 07:44

Are hotplate stirrers unreliable and temperamental or am I just abusing them too much?

I've had a Chinese one that the element burns out on because I used it to boil something dry.

I have had another Chinese one which works but the magnets keep losing strength presumably because of the heat and their curie point.

I have also invested in some better ones as a result of the above, I have an IKA RCT Basic which was working fine until I left it on too long and now it gives me a warning of err 25 which I think means something in the safety circuit has failed.

I've also got a slightly older IKA RCT Basic, an older one without the digital display, it's in good condition but i'm scared to use it in case it breaks! lol

I know a couple of these issues are due to me leaving it on too long but I thought the likes of the IKA ones would be rated for continuous use.

greenlight - 15-7-2022 at 10:17

I wouldn't say they are unreliable. I have never brought Chinese hotplate/stirrers though. Only a Chinese heating mantle.

I have a Corning 420 that has never given me an issue at all, but at the price they are it shouldn't.

I had an IEC brand hotplate/stirrer that had lasted about 10 years and the stirring motor only broke a few months ago. Heating plate still works fine. Stirring motor is not completed broken, just doesn't engage anymore from the dial.
That plate has put some hours in over the years though I tell ya.

They are so good I brought another with a Teflon top plate that will probably see me through the next ten years.

I have not paid less than 450 dollars for a hotplate/stirrer and at the extra cost of buying a non Chinese brand, they are worth every dollar in quality and efficiency.

I don't know why you're IKA plate has broken like that. That is a decent brand and it should be able to heat and stir continuously as all medium to high range plates should.


[Edited on 15-7-2022 by greenlight]

B(a)P - 15-7-2022 at 14:55

Have a look at my post here you can see just how fine the element is on a cheap stirrer. Having never dismantled a more reputable brand hotplate I have no idea what their elements look like, but I would be very curious to see one.

valeg96 - 20-8-2022 at 05:21

IKA RCT Basic hotplates are only good for showing off your money at 800€ each and stirring under mild temperature.

They are too slim and highly packed with microelectronics inside, so the PCBs are very close to the heating element. Granted, they won't burn and catch on fire, but being so close to heat they can be easily fucked up by harsh use.
They are also impossible to repair, your only chance is to find 2-3 faulty ones and try to combine the different pieces until you make one that works. An awful purchase overall. And if you need assistance from IKA, expect a 200€ bill for a new PCB or a new heating element.

With hotplates you should look for things that are thick and solid, maybe with an older simpler circuit inside. The best ones I've ever used are the Heidolph 2002 and 3002. They are indestructible and very common on the market, so if one breaks you can easily find some spares and even a kid could work on them.

[Edited on 20-8-2022 by valeg96]

Dr.Bob - 20-8-2022 at 15:25

If in the US, I would go for a Corning, PC 320 or similar, they will last for many years. IKA models work OK in Europe, but the ones modified for the US are not as reliable as the 220 V models. They are also nearly impossible to repair. Even i have been able to fix some Corning models, and I am not great with electronics.

a used Corning should be $100-200, and will work well. Some Fisher or VWR models are good, but hard to know who made them, newer ones are liklely not as good as older ones.