Electric hotplate mod

[HelmetHeid]

Hey,

I've got an electric hotplate I'm thinking about modding to get rid of the cycling. It's a UK 220-240v 1.5kW.

On the picture of the internal wiring, I'm guessing that if I connect both of the red wires that I've circled, the thing should run on constant full power. Is that right?

But then if I connected something like the controller below to the the red cabling and the white cabling then I could control the power used by the element - is that right?

https://www.amazon.co.uk/dp/B07F56ZGK1/ ... xCb70C7YCE" onclick="window.open(this.href);return false;" rel="nofollow

Although I'm not sure if the little black box (circled in the other picture) is a rectifier to convert the AC power to DC for the element to use. And if so, I should probably get a DC controller.

Sorry, I'm not amazingly electrical - i know a little bit from solar installations and other bits and bobs but it's not really my field.

[HelmetHeid]

Or maybe I could wire it so it's always on, then plug it into this to control the power?
https://www.amazon.co.uk/dp/B07KYM3XGW/ ... xCbJ9FJ3KN" onclick="window.open(this.href);return false;" rel="nofollow

[still_stirrin]

Or maybe I could wire it so it's always on, then plug it into this to control the power?
https://www.amazon.co.uk/dp/B07KYM3XGW/ ... xCbJ9FJ3KN" onclick="window.open(this.href);return false;" rel="nofollow

This sounds like a better option.

The bi-metal thermostat is the element in the photo that the red (hot lead) goes to and from before connecting to the heat element terminals. Eliminating that thermostat will give you full power 100% of the time. With the external motor controller you should be able to control the power running through the modified hotplate.

I don’t believe there is a rectifier circuit (to convert AC power to DC) because the heat element is a purely resistive load, so it shouldn’t need a non-sinusoidal voltage to work. It will work with AC as well as DC.

Incidently, what is the make and model of hotplate you’re working with?
ss

[HelmetHeid]

Great, thanks for that. I'll bypass the thermostat and plug it into the controller to manage the power draw.

The wires look a bit flimsy, so I reckon I should stick some insulation in to make sure the cabling doesn't cook. Maybe some fibreglass between the cables and the metal surface.

Not sure what the model is, it was just sitting about in my kitchen. Think it might be this one:
https://www.amazon.co.uk/dp/B07C49V5N6/ ... xCb4ZS8RBP" onclick="window.open(this.href);return false;" rel="nofollow

[MtRainier]

From recent experience, I can advise you that you should make sure that any electrical connections you make in there that bypass the thermostat should be heat-proof. I used a plastic wire nut which melted.

Also, there is likely a thermal fuse built in to one of the power wires that is connected to the heating element. It might be under some of the electrical insulation. Since the hotplate will be turned on much longer than it would be to cook something it will get hotter inside, I guess. Once the thermal fuse blew on mine it basically became trash.

I had plugged it into a power controller (the still dragon controller kit), which worked well until the fuse popped, heh.

I find this to work much better for my little boiler that I use to infuse gin:

https://www.ikea.com/us/en/catalog/products/10343776/" onclick="window.open(this.href);return false;" rel="nofollow

The power can be varied in 200W increments and doesn't cycle on and off when set. Also, the boiler that I got (the small 3 gallon one from MileHi) turns out to be induction compatible. You're probably not in the US, but maybe your boiler is similar.

[still_stirrin]

I agree with MtRainer’s comments too. It’s going to get hot inside the stainless shroud. Insulate the wires if you can (I used woven glass insulation from a surplus store...it’s the same insullation used on electric stoves’ wiring).

Also, I put fiberglass insulation (water pipe heat insulation) around the inner shroud so that all the wiring and internal electrical devices were isolated/insulated from the heat element. Of note, in my hotplate there is a shroud that ports air through the hotplate housing from below (holes in the bottom panel for vents) up through the element (which is a spiral stovetop element). Heat convection helps to keep the hotplate housing from getting too hot.

And finally, I got a little 2” fan (120 VAC) that is switched and also helps vent the internal heat build up to the outside of the hotplate housing. It all gets a little crowded inside the shroud, but cleaver placement of components helps. Incidently, the heat control circuit board I built for the triac and comonents is mounted inside the hotplate housing. So, the insulation and cooling convection helps protect that as well.

As for the electrical connections, I soldered wire eye terminals to the wires and then used a small screw and nut to join the wires terminals. Again, these type of electrical connections were covered with the woven glass wire insulation. The screw joints allow connection/disconnection if needed, yet they won’t (potentially) melt like plastic wire nuts might.

Always keep safety in mind when doing design and modification to a UL approved device like this. You absolutely don’t want to create a safety hazard for yourself.
ss