Immersion heater switch?

[Hobsini]

We have an immersion heater that’s stopped working. I’ve reset the connections and element with a multi-meter and they all seem good. What else could it be? Is it possible it’s the switch? I assume if it were I wouldn’t get a volt reading (with a voltage pen) at the thermostat?

 

[jurassic sparkk]

We have an immersion heater that’s stopped working. I’ve reset the connections and element with a multi-meter and they all seem good.

What exactly did you test with the multimeter?

 

[Hobsini]

Voltage pen at the switch and thermostat and multi-meter for resistance at the switch and element/thermostat. We used to see a slight spark at the switch when it worked but now nothing.

 

[Johntheo5]

Are you getting voltage at both terminals on the thermostat?. What element resistance are you getting?.
Also, post a photo of the immersion.

 

[Harry Bloomfield]

Voltage pen at the switch and thermostat and multi-meter for resistance at the switch and element/thermostat. We used to see a slight spark at the switch when it worked but now nothing.

What resistance value, did you measure across the element terminals?

 

[Hobsini]

Will check the terminals again. Resistance was 18.

 

[Johntheo5]

Will check the terminals again. Resistance was 18.

Post a photo if still in trouble.

 

[Harry Bloomfield]

Will check the terminals again. Resistance was 18.

18 what?

 

[jurassic sparkk]

Ohms probably, 240v divide 12.5 amps = 19.2 ohms.

 

[Johntheo5]

18 (if) ohms, = 230x230/18, 2939 watts at 230V or, 240x240/18, 3200 watts at 240V.

 

[Harry Bloomfield]

Ohms probably, 240v divide 12.5 amps = 19.2 ohms.

Assuming Ohms, then the element is likely OK. OP suggests they get a live indication with a volt stick, I would suggest the OP checks if the neutral is also showing as being live, with the volt stick.. If so, it will suggest the neutral has somehow been lost.

 

[CBW]

I assume if it were I wouldn’t get a volt reading (with a voltage pen) at the thermostat?

You could get voltage, depending on how low the voltage pen indicates and they’re not the most reliable. Why not test for voltage correctly?

 

[Johntheo5]

It would help immensly if we had a photo, it could be a side mounted immersion or a top mounted single element immersion or a top mounted dual element immersion with a short and long element, (unlikely since only one element resistance provided). Below is a top mounted dual element immersion where one thermostat switches the common neutral and has a separate over temp thermostat marked 6.

 

[Hobsini]

Yes, 18 Ohms. Tried volt stick at neutral and got an indication. Included a picture as well.

 

[terryplumb]

Forget the volt stick and measure the voltages with your multimeter.
Measure the live to neutral ,and live to earth. And test the live at both sides of the thermostat.