Immersion resistance sink / bath

Hotblack Desiato

I replaced the immersion switch today. The plumber who installed it had driven the neutral screw into the insulation rather than the conductor, it made weak contact and overheated over time, the switch showed signs of melting.

The element appears fine, one was 20 ohms the other was 28, I presumed the lower resistance / higher current one was bath and the other was sink.

Can anyone verrify what bath and sink element resistances I should be looking at, just in case I've reversed them Thanks.

2011

Divide the power stating of the immersion (in watts) by the voltage (230) and that will give you the current that it draws.

So a 3 kW immersion will be around 13 amps.

Power = the square of the current x the resistance
3000 = (13^2) x R
R = 3000/169 = 17.8 Ω

Bruthal

Close to 20 is the bath, 28 sink.

Bruthal

Or i suppose I= root (watts/r)

Hotblack Desiato

Just had a potential mix up between the switched live for bath and the switched live for sink, it stands to reason that the higher current draw is the bath element.

Thanks.

Bruthal

Hotblack Desiato wrote: »

Just had a potential mix up between the switched live for bath and the switched live for sink, it stands to reason that the higher current draw is the bath element.

Thanks.

You can check the meter runs faster on bath than sink as another test. Its not absolute proof an immersion is connected correctly, but it would be very likely it is.

Hotblack Desiato

Yep about 4 seconds for a rotation of the meter on sink about 3 seconds on bath so looking good.

riddles

Hi

a kindly member recommended this timer switch for the immersion. I currently have a duel on off switch with bath or sink switch. As I am clueless is the bath sink switch just a different current level. And if I replace it is there an impact on the bath sink function?

https://www.amazon.co.uk/gp/product/B0031KCWJI/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Thanks

R

coylemj

riddles wrote: »

a kindly member recommended this timer switch for the immersion. I currently have a duel on off switch with bath or sink switch. As I am clueless is the bath sink switch just a different current level. And if I replace it is there an impact on the bath sink function?

That timer is rated at 13 amps so it will handle the load no problem. In terms of wiring, you will keep the Bath/Sink switch to control which element is getting juice. You will need to remove the mains feed from the Bath/Sink switch and run it into the timer, then run a short wire from the timer to the Bath/Sink switch.

On the Bath/Sink switch, you will normally leave the On/Off switch permanently On and control the current via the timer. Flick the Bank/Sink swithc to Off when going on holidays.

The timer you linked to is very basic, you can only switch on the immersion by pressing the button which means someone has to get up early to start the cycle! There are better switches which incorporate a 30/60/90 minute boost option plus the ability to start and stop at given times, up to several cycles each day. Here's one such timer.....

https://www.sangamo.co.uk/collections/powersaver/products/powersaver-select

If you'd like to control the immersion from a mobile app, consider this timer ........

https://www.timeguard.com/products/time/immersion-and-general-purpose-timeswitches/wi-fi-controlled-fused-spur