Wiring a timer into a switch for an immersion heater tank

[colboy8]

Hi,

I have just moved into a property with electric heating and an electric imersion tank. The property is on an economy 7 tariff but the immersion heater has just an on off switch that turns it on. There is a wall mounted "manual" (with a spinning dial and little pegs to push up or down depending on when you want it on or off) and I would like to wire this in so i can set the timer to come on when the electricity is cheapest (naturally)

So, the timer has just four connections, Live in, Nuetral in, live out, neutral out.

The switch is 3 core? I think thats right, it has two different sets of colours but basically its earth, live and neutral, right?

So how do i wire it in. currently the main electric cable comes down from the ceiling into the switch and then out the bottom to the immersion.

what do i need to add to the switch and to the timer to get it to work?

I want the switch to work only when the timer says so, if i need to turn it on during the day ill just use the timer, it will mean i dont forget to turn it off anyway.

thanks for any help, its appreciated.

Col

 

[RF Lighting]

Live, neutral and earth from the existing double pole isolator feeds the new timer. Live and neutral go to L & N in on the clock. Connect the flex which goes to the immersion heater to live and neutral out, and join the earth from the flex to the earth of the cable between the isolator and the clock with the earth terminal on the clock if there is one, and if not with a piece of 15A strip connector.

Don't forget to safely isolate the mains before you start work.

 

[securespark]

I've fitted one of these: http://www.tlc-direct.co.uk/Main_Index/Water_Heating_Index/Immersion_Heater_Timers_2/index.html

It's been utterly reliable & been in a couple of years.

But, it is entirely manual and cannot be set to come on while you're out.

Plus, it has permanently on blue lights, even when the switch is not set to heat the water, so if it on show, it may annoy. It does not bother us, though.


These I have fitted when I was self-employed:

http://www.tlc-direct.co.uk/Manufacturers/Timeguard/Immersion_Heater_Timers_1/index.html

I have not had an issue with them.

Mine at home:

 

[colboy8]

Live, neutral and earth from the existing double pole isolator feeds the new timer. Live and neutral go to L & N in on the clock. Connect the flex which goes to the immersion heater to live and neutral out, and join the earth from the flex to the earth of the cable between the isolator and the clock with the earth terminal on the clock if there is one, and if not with a piece of 15A strip connector.

Don't forget to safely isolate the mains before you start work.

So, i understand some of this but i would like to just check a few things,

Firstly thanks for the post, its exactly what i needed but as i am a bit of a simpleton i dont understand some of the terminology.

So I should take the switch out of the entire occaision, no problem, join the live and neutral of the cable to the main fuse box to the live and neutral in terminals, take the cable from the imersion heater and do the same with the live and neutral on the out mside of the timer.

So my problem will be that the two earth wires, one from the fuse box in and one from the immersion out, will be unused.

are you saying that i should then join them together?? with a piece of 15a strip connector?

Then once this is done, the switch will have no wires in it at all, the timer will run the imerrsion and no switch will be involved, if the timer says off, it will be off, it it says on, it will be on.

i hope i understood right, but before i mess up the electrics, i just want to be double sure.

thanks

col

 

[wingcoax]

Yes, just join the earth wires in a choc bloc. You really need to keep the switch in the circuit as a safety measure. Fit your timer after the switch with a short length of cable of the same size as the existing cable.

 

[colboy8]

Yes, just join the earth wires in a choc bloc. You really need to keep the switch in the circuit as a safety measure. Fit your timer after the switch with a short length of cable of the same size as the existing cable.

Thanks for this concise and laymans answer, i think i am ready to try and tackle this now as I have the cable and a choc block somewhere (ill have to route around for it) and then i should be up and running,

fingers crossed!!

Thanks to the whole forum for existing, this is the second time i have posted a question and had a suitable answer, congrats on the generosity of people for their time and expertise, it is not without thanks!!!

Col

 

[kai]

In very general terms, the layout will be something like this. First the cable from the fusebox feeds into an existing switch. Leaving the existing switch in place, run a short length of suitable cable to the timer inputs.
From the timer outputs, run the immersion flex onto the element itself.
Earthing connections are made with either the earthing teminals usually found on the back of the switch or its mounting box, or as the other poster suggests, use a piece of 15amp connector box to join the earths.

 

[ericmark]

Well I could not follow what was being said. I was a little surprised as I thought the normal was to have two immersion heaters the lower one being set a bit hotter and connected to economy 7 and the upper one connected to an isolator as a boost should one run out of hot water.

Should one forget to switch off the upper one the lower one should still stop it from coming on unless running out of hot water.

Although one could use a single element one has to be careful that both supplies can't be switched on together. Otherwise back feeds could have huge amounts of power flowing.

So what ever is used it should have change over contacts and the immersion heater would be connected to common.

Although we use the wording economy 7 there seems to be two completely different systems. See Wikipedia In the old days of white meter the supply only switched on during the night and one had two completely separate systems. However latter it was changed so anything one used during the qualifying time was on cheap rate. The latter lent itself to have washing machines, tumble driers and immersion heaters all running over night and also allowed one to use a boost for heating during the day.

As a result it is important to work out exactly which system you have.

 

[colboy8]

Hi Ericmark,

I think the system you are describing is the way that it is usually set up for economy 7. I had a newly built falt some years back, two in fact and they both had the system you described.

The house i currently live in is 600 years old, so the immersion was probably put in some time later on, i dont even know if it would have been put in before the economy 7 tarriff existed. I do have storage heaters with two sockets/switches. one that turns it on anytime and another that only lets it come on during the economy 7 timeframe.

My immersion heater has only one swtich and one cable going into it, therefor i am assuming (and i hope not to be wrong! but if anyone knows or has experience that is different please speak up!) that it is just one feed to the mains fuse box and not the economy 7 bit, or whatever it would be going into to only work at economy 7 times.

so by wiring in this timer i can choose to have the water heated up at the cheap rate as opposed to now where i have to manually turn it on and off and this lead to me leaving it on once for three days, and whilst it has a thermostat it was still pretty expensive.

on a side note, it uses 9 units of electricity to heat it up over three hours until the thermostat cuts it out, does this seem about right to anyone? i have no idea how big the tank volume is, sorry.