Titanium Heating Element Electricity

[Graz]

Does anyone know if titanium heating elements have AC mains, DC, or what other electricity through them? Obviously AC or DC, but it is direct wall current switched on and off, is it DC, or is it some other AC waveform?

 

[Ocelaris]

Why wouldn't it just be a resistive load running on ac? Not sure if it's just titanium coated heating elements, but there's no separate power supply, so I'm assuming it's ac. There would have to be some sort of rectifier or similar to switch to a very dirty DC, but I don't know of any reason why it would not just be straightforward ac.

 

[Graz]

Straight AC would be the obvious answer, but that makes is a bit difficult to modulate the power output without a switching power supply, which could be quite noisy (electrically). I was just wondering how it tends to be done in practice, since I don't have access to one to test.

 

[Salty1962]

It's ac, you'd need a controller to maintain the temperature you wanted it at.

 

[Graz]

Do the controllers tend to maintain temperature by switching the heating element on and off or by attenuating the AC signal?

 

[Ocelaris]

Do the controllers tend to maintain temperature by switching the heating element on and off or by attenuating the AC signal?

I'm sure this is a lot simpler than you're thinking it is. They're definitely on or off. You don't really attenuate an ac signal for heating, you would need a big transformer to change the voltage.

 

[kecked]

Ac heaters work by inducing a voltage across a resistive strip of metal. This is fixed. They turn it on and off based on a bimetallic switch which opens and closes the supply voltage based on temperature. Very simple. This is also why they fail. If the bimetallic arcs or sticks closed you cook your tank. Using a controller to monitor the temperature and turn the heater on and off via solid state rely is much safer.

I would love to see a dc heater as most I have leak voltage after a few years. I think it’s the construction that’s at fault. There is no reason water need ever enter a properly sealed heater. Heck put the heater in a jacket in a jacket. Just costs more to do that.

They are all AC in aquariums. Horses and other uses can be dc.

 

[Graz]

Having looked into it more, a triac could be used in much the same way a dimmer switch works, except that the large current switching on in the middle of a wave could put some nasty transients on the power line.