May sound daft, but how does an immersion heater work?

[ericmark]

If an immersion heater was in a tube it would start a flow up centre and down sides, and would mix the water, even without a tube there will be some flow, however today phoned a plumber with idea of having a longer element.

What I don't know is how size of thermostat watts output will change the flow pattern? Does heating water with 250 watt mean less disturbance in the water so smaller quantity heated?

All this is outside my comfort zone.

 

[JohnW2]

If an immersion heater was in a tube it would start a flow up centre and down sides, and would mix the water, even without a tube there will be some flow,

Heater water will rise (flow') up, as a result of which relatively unheated water will fall ('flow') down- that's just simple convection. There wouldn't not be all that much 'mixing' of hot and cold water, since they will 'move' to the top and bottom of the cylinder respectively. Again, that's how convection works.

What I don't know is how size of thermostat watts output will change the flow pattern?

I don't understand what you are talking about, or asking.

Does heating water with 250 watt mean less disturbance in the water so smaller quantity heated?

How are you going to heat water 'with 250W'? Is this what the iBoost thingy does? I wouldn't say that heating water 'disturbs' it, it's really more a case of it resultting in convection currents. If you heat the watere less, those convection currents will obviously reduce.

Kind Regards, John

 

[ericmark]

Yes a 3 kW water heater can use 150 watt to 3 kW to match excess solar power, so the disturbance at 150 watt will be a lot less than 3 kW.

 

[JohnW2]

Yes a 3 kW water heater can use 150 watt to 3 kW to match excess solar power, ...

... presumably by varying the voltage, according to how much 'excess solar power' there is? That sounds a little complicated!

so the disturbance at 150 watt will be a lot less than 3 kW.

As I said, I'm not sure that 'disturbance' is really the right word. If there is less heating (due to decreased power/voltage to the element) there will be less water heating, and therefore less heated water 'rising up' (and less cooler water 'falling down'.

Kind Regards, John

 

[ericmark]

... presumably by varying the voltage, according to how much 'excess solar power' there is? That sounds a little complicated!

I am not sure how it works. It warns the output is DC, and it shows the varying output. We get a display like this

which seems to be an infinitely variable output, so some sort of inverter, it says

Control type: 1B (Pulse Width Modulation)

 

[flameport]

It's PWM of the AC supply, in the same way that a triac lighting dimmer works.

 

[JohnW2]

It's PWM of the AC supply, in the same way that a triac lighting dimmer works.

That makes sense, but eric seemed to tell us that it was DC - although, even that is true, I suppose PWM is just as applicable to DC as it is to AC.

Kind Regards, John