Immersion switch replacement help

[weapon]

Eh...up folks!!

My mums house is heated by her coal fire which does her hot water and radiators. She has an immersion switch (photo at bottom) which you have to use when the coal fire has not been on so that you can get some hot water.

I'm looking to replace the switch with a timer switch so that there will be hot water in the morning for her so that she can have a bath as just now she has to get up half an hour before she needs a bath to put the switch on and wait for it to heat the boiler for hot water.

I'm looking at these kinds timer switches, nothing too complicated for my mum:

http://www.amazon.co.uk/Timeguard-TS900-Immersion-Heater-Controller/dp/B002MFHKF4/ref=sr_1_1?ie=UTF8&qid=1306309566&sr=8-1

http://www.maplin.co.uk/electronic-immersion-heater-time-controller-12726

http://cgi.ebay.co.uk/24-HOUR-MECHANICAL-IMMERSION-HEATER-TIMER-LG-MIHT-/270747076145?pt=UK_Home_Garden_Hearing_Cooling_Air&hash=item3f09c88631#ht_1472wt_942

Can anyone tell me first of all if i can replace her current switch with a timer switch and if so are the ones i'm looking at compatible??

Any info or advice would be much appreciated!!!

Thanx

[Taylortwocities]

Sure, they are all suitable for immersion heaters, that is why they are called "Immersion Heater Timers".

I do not know how good your mother is with technology, but the middle one might be a bit tricky for her to programme. It's OK if you are prepared to go over there to set it up every time....

One thing. You need to leave the switch in place and wire the timer into the cable that goes to the immersion. The switch will need to be left in the ON position but it will be a necessary point of isolation for the immersion and its timer.

[kai]

The third one, i.e. the one with the captive tappets (pins to set the time) is the most suitable, it is simple to understand, and fits neatly on a standard square socket box (flush or surface mount). No loose pins to go missing.

[weapon]

Good stuff, thanks very much for your replies!!!!

[autocrazy]

Hi OP (weapon)

I am new to the forum

Could you confirm which one of the three timer switches did you buy and install. I am in a very similar situation as yours and in a dilemma as to which switch I should buy and install.

I am torn between the following 2 switches

http://www.amazon.co.uk/Timeguard-TS900-Immersion-Heater-Controller/dp/B002MFHKF4/ref=sr_1_1?ie=UTF8&qid=1306309566&sr=8-1

http://www.amazon.co.uk/MECHANICAL-IMMERSION-TIMESWITCH-LGA-LG-MIHT/dp/B0066NN5W0/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1333463486&sr=1-1-catcorr

My priority is ease of installation, good quality and may be after a year since your last post you have some guidance to share?

Also unlike what Taylortwocities mentions, I want to get rid of the switch and substitute for timer - did you do the same?

Is it a straight forward DIY job? I can do electrical connections (once the mains are turned off!)

Anyone else who can guide me is more than welcome to contribute

[EFLImpudence]

autocrazy wrote:

Also unlike what Taylortwocities mentions, I want to get rid of the switch and substitute for timer - did you do the same?

It was not a 'mention' - it was /is the correct information.
The switch must be retained and the timer wired to the cable between the switch and the immersion.

In most properties this cable is visible and easily accessible so either timer quoted will be suitable.

[streetlighter]

Im sure Smiths Timeguard make a 13a fused connection unit with a built in timer that fits onto a standard 1 gang box.

[EFLImpudence]

They do.

http://www.timeguard.com/products/time/immersion-heater-controllers/fst11a-supplymaster-24hr-fused-spur-timeswitch

[EFLImpudence]

duplicate.

[autocrazy]

Hi

I have done a lot of reading and find it confusing as to why I should have a seperate switch and a timer.

I am currently considering this timer

http://www.amazon.co.uk/Masterplug-TMIH24-MP-24-Hour-Immersion-Segment/dp/B003XUW0IY/ref=pd_sim_kh_1

I have found the wiring instructions, which no where specifies the need for an additional switch - see attachment.

Perhaps if I can be explained why only a timer shall not suffice. When I do wish to completely switch it off (when on holiday), I just need to pull the segments out to disconnect - isn't it?

[EFLImpudence]

autocrazy wrote:

I have done a lot of reading and find it confusing as to why I should have a seperate switch and a timer. Perhaps if I can be explained why only a timer shall not suffice.

he immersion instructions do. See wiring - section 2

http://www.heatraesadia.com/docs/Immersion_-_Issue_3_-_36005868.pdf

Quote:

When I do wish to completely switch it off (when on holiday)

That is the point - the timer will only disconnect the live conductor.

For isolation the neutral must be disconnected as well.

Should a fault occur between neutral and earth switching only the live will not isolate the fault.
If you have RCDs protecting your cabling this could result in half (or all, if only one RCD) of the circuits in the house being disconnected until the fault is isolated by actually removing the wires from the immersion - instead of just switching off.

However, the link above (lead to by streetlighter's post) does show a timer which includes a double pole switch.

Unfortunately it also contains a 13A fuse which, if your immersion is wired conventionally, is unnecessary and in my opinion undesirable.

[kai]

The safest way, is to leave the existing switch in situ, and place the timer in between the old switch and the immersion element. This way you have both functions available, i.e. the timer controls and the Holiday Isolation, where the existing double pole switch is turned off when on holiday.