Advise on fitting immersion heater timer controller Ask questions and find answers to many subjects relating to electrics and electrical work

[diy2009]

We have an upstairs hot water immersion tank located in a small cupboard that is activated using a manual switch (with red indicator light) in the kitchen down stairs. According to the top of the tank, the immersion heater is rated at 3kW.

I purchasd a 24 hour immersion heater time controller today (Homebase own brand) and would like a little advise as to installation. Firstly the controller switch rating is 3kW, 13A resistive, 5A inductive. As the heater is rated at 3kW, should I be looking for a time controller which is actually rated to operate at greater than 3kW or is it safe to use?

Secondly, the immersion heater is wired directly into a fused switch inside the cupboard. I assume (from the instructions) that the time controller should be wired between the heater and the fused switch inside the cupboard?

Finally I assume once the immersion heater is wired to the time controller for timed activation, the switch in the kitchen needs to be left on at all times?

Apologies if these questions sound naive or stupid, but I'd rather be safe than sorry. Thanks in advance guys.

[singer]

[quote]I purchasd a 24 hour immersion heater time controller today (Homebase own brand) and would like a little advise as to installation. Firstly the controller switch rating is 3kW, 13A resistive, 5A inductive. As the heater is rated at 3kW, should I be looking for a time controller which is actually rated to operate at greater than 3kW or is it safe to use? [/quote]

If the timer is rated 3kw then it will carry 3kw so is fine to use on immersion heater.

[quote]I assume (from the instructions) that the time controller should be wired between the heater and the fused switch inside the cupboard? [/quote]

Correct. Disconnect flex from fused switch and connect into "out" terminals of timeswitch. Install same sized flex from fused sw to timeswitch "in" terminals. ENSURE EARTH IS CONNECTED.


[quote]Finally I assume once the immersion heater is wired to the time controller for timed activation, the switch in the kitchen needs to be left on at all times?[/quote]

Also correct. Timeswitch needs to be live at all times to run clock motor.
Fused switch in airing cupboard will need to be ON also.

[diy2009]

Many thanks Singer for the confirmations. One more question if I may. In the fuse box, the trip switch for the immersion heater has got a label 16A. Does this mean that the immersion heater necessarily draws 16A and is it then safe to use the controller which is a 13A device?

[sparx]

Hi, not much choice as there is no such thing as a 13A mcb so has to be 16A, the heater will only draw its rated 13A current no matter what size supply.
the cable is protected by mcb and as you have a 'fused switch'in cupboard which should take care of timer/heater if they go wrong, assuming there is a 13A fuse fitted ,
regards Sparx

[diy2009]

I need to purchase an additional length of cable for the controller switch. The local homebase would not advise me as to what gauge of wiring I should be using for an immersion heater switch. What is the corrent type of electrical wire?

[sparx]

Hi, good for Homebase, they aren't qualified to give such advice & would leave themselves open to litigation if they give wrong advice.
If you are extending after 13A fused spur then 1.5mm would do for short length.
regards SPARX

[diy2009]

I have purchased a coil of 3 core round flex (to BS 6500) with a max rating at 240 V of 16A, 3840 W. I assume this would be more than sufficient to cope with a 3000 W immersion heater?

[singer]

Yep sounds fine!