# wiring a digital timer to an immersion heater element.



## NOAH (28 Sep 2005)

I wired a digital timer to an immersion heater element today and foolishly thought it was a simple case of 3 wires, ie live in live out, neutral, and earth but when I had wired the switch I want to turn the thermostat in the heater element down and lo and behold there was a 4th wire, coloured black. I switched on the timer and with a tester checked for current to element and got zilch. Oh oh, where have I messed up?  The original switchw was one of those that had a flip switch for on off and anoteher for sink or bath. I was in  a rush and did not take too much notice.

Does it mean I HAVE TO RETAIN the on/ off switch  socket and use the timer with that? The timer fits in a wall box so that's why I just went for timer.

This is not my set up, its my sister in laws and the immersion is/was used with a dual fuel ch system ie back boiler and oil. I disconnected the thermostat that was linked to the on/off as well. The thermostat for the dual feed would switch on the motor when back boiler heated up. There is no back boiler used now.



Help?

noa--


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## beldin (29 Sep 2005)

There are two elements in most of these heaters , the short one for sink and the long one to heat the bath water. It really helps to retain the bath/sink switch. I suppose you could leave just one connected but it is a bit of a mess.
Best way is to restore the original switch  which should have the 3 wires coming in from your timer and 4 going out to the immersion. 

Bye the way where did you get a digital timer for an immersion. I was looking for one a while back and they didn't seem to be available. I had one in a house years ago but it was a cheap one and burned out after a year or two.


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## legend99 (29 Sep 2005)

NOAH said:
			
		

> I wired a digital timer to an immersion heater element today and foolish thought it was a simple case of 3 wires, ie live in live out, neutral, and earth but when I had wired the switch I want to turn the thermostat in the heater element down and lo and behold there was a 4th wire, coloured black. I switched on the timer and with a tester checked for current to element and got zilch. Oh oh, where have I messed up?  The original switchw was one of those that had a flip switch for on off and anoteher for sink or bath. I was in  a rush and did not take too much notice.
> 
> Does it mean I HAVE TO RETAIN the on/ off switch  socket and use the timer with that? The timer fits in a wall box so that's why I just went for timer.
> 
> ...



make sure for christs sake that the timer in question is rated for the very large current that the immersion draws...you should be sourcing these type of things from a specialist supplier such as Heat Merchants, rather than for example off a shelf in Roches Stores.


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## Leo (29 Sep 2005)

Yes, you must retain the original immersion switch, without it you will not be able to select from the bath or sink elements. The live out of your timer connects to the live in of the switch. Immersion elements are generally rated about 3kW, so, as legend99 says, please make sure the timer can handle this, most can't! Failure to do this will at best result in a rurned out timer. Timers that can handle immersion loads generally state this on the packaging.

B&Q have a suitable "Ranger 3" timer for abour €44, though you might get a better deal or more choice from a specialist electrical suppplier. 
Leo


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## NOAH (29 Sep 2005)

thanks both, I am getting too old for  this. I missed the sink bit. I will put back original switch if I can remember the wiring set up!! I got the digital timer from the UK, it is available from a source in Dublin as well but when I rang Dublin it was a case  of we have none in stock will have them in next week, if i had a pound for everytime i was told this by suppliers in ireland i would be rich now.

here are the links.

[broken link removed]

I got the CTU9000, it is a doddle to use and will almost make the tea.

u order it from here, put  in ctu9000 as the search. It came within 2 days!!



and this is the Dublin contact.

Please try Charles Nolan, Dublin6 on 00 353 1 4906611

If u are not in a rush maybe I will have a ctu9000 on my hands that will not be used!!  It will be in 2 weeks though as I am taking a break.

Thanks for replies. 

noah


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## NOAH (29 Sep 2005)

I did check the ratings before I bought it and it is 3kw.

noah


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## beldin (29 Sep 2005)

Thanks for the link , it seems fine for the job.
Pity they didn't add in a provision for a sink/bath option.. 
Must keep it in mind if my own mechanical one fails as they seem to offer much more flexibility regards weekend timings..


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