Can someone explain why I have to use this dogs breakfast?

[BatGuano]

When I try to use either of these controllers individually, at some point I cannot dial down the power all the way, only a little bit. The only way to get some sort of control is to use two controllers in series, and it takes a LOT of fiddling to get a stable result. I am running on a 240v 60hz circuit.

[BatGuano]

I should also mention that this is powering a 3500w 240v low density heating element.

[Yummyrum]

Do you mean that as you turn the knob down , it reaches a point about 70volts then the display goes out ?

If this is what is happening , then it is simply because the display needs a minimum voltage for its electronics to keep working .

Once you go lower, the element is still getting lower power , it’s just the meter isn’t able to tell you .

If you can get an old incandescent lamp and plug it in you’ll see what I mean .

[jonnys_spirit]

Can you provide detailed info about the controllers, what components they are built with, and wiring details for each?

Thx,
J

[Yummyrum]

Also worth mentioning is that no simple Phase controller with a Pot will operate from 0-100 on the dial . They pretty much will all give close to 100% power when turned up full , but due to Pot manufacturing tolerances , the “zero” end could be anywhere from 0-30 on the dial .

It gets worse you are trying to operate a controller designed for 240v on 120V .

[acfixer69]

Looks to have 240v but using a120v outlet. Not a safe Amp/voltage condition.

[Northsouth]

I got the exact same device (left side one) and exact same problem with a 3000w element (3 resistors). It happens after running for a while (here it is 220).
My suspicion (have no clue of electricity) is that modulating the voltage, it overheats, and then it goes into "protection mode" and just let everything through, 220 or 110. It got really hot, I opened it up after disconnecting, and the heatsump (or whatever it is called) was burning hot.

Also tried removing a pin and use only 2 resistors which means 2000 w. When doing that, it worked, but it is not 100% comparable, as I did not reduce voltage over longer time in this condition, due to the limited power. I will try that as well.

Probably, it is too small, even if it is supposed to be for 4000w.

There must be someone here that could give a pointer.

[NormandieStill]

I got the exact same device (left side one) and exact same problem with a 3000w element (3 resistors). It happens after running for a while (here it is 220).
My suspicion (have no clue of electricity) is that modulating the voltage, it overheats, and then it goes into "protection mode" and just let everything through, 220 or 110. It got really hot, I opened it up after disconnecting, and the heatsump (or whatever it is called) was burning hot.

Also tried removing a pin and use only 2 resistors which means 2000 w. When doing that, it worked, but it is not 100% comparable, as I did not reduce voltage over longer time in this condition, due to the limited power. I will try that as well.

Probably, it is too small, even if it is supposed to be for 4000w.

There must be someone here that could give a pointer.

I have a 3 element heater (4500W) as well and mine is wired as three individually controlled elements. One element is wired to a cheap eBay "10000W" controller, the other two are simply switched (I have a switch over the controlled element as well so it can be isolated. While this doesn't give a continously variable 0-4500W from one dial, it does give fairly fine control over a 1500W range which can be boosted to 1500-3000W or 3000-4500W. And it doesn't stress the dimmer unit which is as best rated for about half the claimed range!