Immersion heater - New switch install help

[axumazza]

Hi,

I'm about to switch to an energy tariff whereby i think it would be better/cheaper to heat my water via my immersion heater and not my gas boiler.

I have a plain old switch attached and wanted to install a new WiFi-enabled switch or, failing that, a timer switch.

I've just opened up the switch and there's 7 wires! Most of these switches seem to have 3 connections, so i'm a bit lost as to what i'm going to do.

It seems that one set of wires is running upwards and powering the Hive heating so my assumption is they can be grouped together in 3 sets ?

There are :
2 green and 1 green and yellow wires
2 red
2 black

As you can see below, the 2 red and 2 black seem to be going into the same connection.

Any advice would be greatly appreciated.

 

[Avo Mk8]

You have a double pole isolation switch for your immersion, the L and N coming in at the top and as you suggest going off somewhere else, and hopefully an earth wire with each of those. Then at the bottom of the switch the L and N of the flex to the immersion, and the associated earth wire.
The switch is double pole for safety, so power can be switched off completely locally. These days a fused double pole switch (FCU) would be used.
The wifi controller you are suggesting has only a single pole switch if it only has three terminals. So if you want to use one of those you should leave a switch in place (preferably replacing the existing with a fused version - FCU), and connect the output of that to your new controller, and then to the immersion.
Alternatively if you want to have a wifi unit in the place of the switch you have, I suggest choosing a double pole fused wifi FCU type, made for the purpose, eg:

Timeguard STFSTWIFI Electrical Timers

Buy Timeguard STFSTWIFI Electrical Timers online at Shop4 Electrical & get FREE Next Day UK Delivery when you order by 2pm & spend £60

www.discount-electrical.co.uk

13A DP Wi-Fi Switched Fused Spur White

Works with Wi-Fi and 4G

www.cef.co.uk

Admittedly the apps for the above are perhaps not so slick, but they do work

Sorry to be direct, but given the age of the cables and that switch, your uncertainty about the wiring, and the relevant regulations with which you may not be very familiar, you should seriously consider using an electrician to make the change.

 

[axumazza]

Thanks so much for the reply. That makes sense to me.

I had read about putting a switch in-between the heater itself and the old switch that's in place....i don't think that's going to work, the space is incredibly tight where it is so i think just directly replacing the entire old switch would be the way to go.

And no worries for being direct, I will more than likely get someone qualified to do the job, i just like to know the details myself, and you're just looking out for my safety at the end of the day so no need to apologise, it's appreciated!

 

[axumazza]

You have a double pole isolation switch for your immersion, the L and N coming in at the top and as you suggest going off somewhere else, and hopefully an earth wire with each of those. Then at the bottom of the switch the L and N of the flex to the immersion, and the associated earth wire.
The switch is double pole for safety, so power can be switched off completely locally. These days a fused double pole switch (FCU) would be used.
The wifi controller you are suggesting has only a single pole switch if it only has three terminals. So if you want to use one of those you should leave a switch in place (preferably replacing the existing with a fused version - FCU), and connect the output of that to your new controller, and then to the immersion.
Alternatively if you want to have a wifi unit in the place of the switch you have, I suggest choosing a double pole fused wifi FCU type, made for the purpose, eg:

Timeguard STFSTWIFI Electrical Timers

Buy Timeguard STFSTWIFI Electrical Timers online at Shop4 Electrical & get FREE Next Day UK Delivery when you order by 2pm & spend £60

www.discount-electrical.co.uk

13A DP Wi-Fi Switched Fused Spur White

Works with Wi-Fi and 4G

www.cef.co.uk

Admittedly the apps for the above are perhaps not so slick, but they do work

Sorry to be direct, but given the age of the cables and that switch, your uncertainty about the wiring, and the relevant regulations with which you may not be very familiar, you should seriously consider using an electrician to make the change.

Of course...I should have known that in this day and age....there's another option :

https://www.amazon.co.uk/SwitchBot-Smart-Switch-Button-Pusher/dp/B07B7NXV4R/

 

[Avo Mk8]

Of course...I should have known that in this day and age....there's another option :

https://www.amazon.co.uk/SwitchBot-Smart-Switch-Button-Pusher/dp/B07B7NXV4R/

Unless I'm mistaken you have a toggle switch, not a rocker or push type. If that's correct, it looks dubious to me if this gadget will actually operate a toggle switch In both directions.
If I'm wrong, and you have a rocker switch, then maybe OK.
But back in the day of your original switch, they tended to require more force to operate!

 

[axumazza]

Unless I'm mistaken you have a toggle switch, not a rocker or push type. If that's correct, it looks dubious to me if this gadget will actually operate a toggle switch In both directions.
If I'm wrong, and you have a rocker switch, then maybe OK.
But back in the day of your original switch, they tended to require more force to operate!

No, you're not mistaken....that's right.

Switchbot has an attachment that pulls the switch back to it's original position.
I'm also doubtful it will have the force to push/pull the switch but it's good old Amazon, so if it doesn't, i can just return it.
I'll let you know how i get on!

 

[brianmoooore]

Amongst the dubious things that can be bought on Amazon, that looks one of the most dubious I've ever seen, Sure that no switch manufacturer would approve its use.
Gas in the UK currently costs about 10p/kWhr. I know that electricity tariffs vary across the UK, but there's none available where I am that can beat or even match that.

 

[axumazza]

Amongst the dubious things that can be bought on Amazon, that looks one of the most dubious I've ever seen, Sure that no switch manufacturer would approve its use.
Gas in the UK currently costs about 10p/kWhr. I no that electricity tariffs vary across the UK, but there's none available where I am that can beat or even match that.

Not sure why...all it is doing is pushing down on a switch, like your finger does...

My gas is 10.4p, my new EV tariff will be 10p during the night, a small saving, but a saving nonetheless.

On further thoughts though, even if electricity was way cheaper, it's probably going to be more efficient to heat via gas due to the way it actually heats the water (plus my immersion doesn't have two elements)!

 

[DPG]

Not sure why...all it is doing is pushing down on a switch, like your finger does...

My gas is 10.4p, my new EV tariff will be 10p during the night, a small saving, but a saving nonetheless.

On further thoughts though, even if electricity was way cheaper, it's probably going to be more efficient to heat via gas due to the way it actually heats the water (plus my immersion doesn't have two elements)!

It would have to put enough pressure on to operate the switch without any arcing, but not too strong that it put stress on the switch or the fixings of its mechanism. Also the required length of travel of the actuator will vary depending on the switch.

Obviously the force and travel required will depend on the type and manufacture of the switch. It will be interesting seeing how precisely this can be adjusted, and how reliable it is.

 

[brianmoooore]

Not sure why...all it is doing is pushing down on a switch, like your finger does...

My gas is 10.4p, my new EV tariff will be 10p during the night, a small saving, but a saving nonetheless.

On further thoughts though, even if electricity was way cheaper, it's probably going to be more efficient to heat via gas due to the way it actually heats the water (plus my immersion doesn't have two elements)!

Difference with a finger is feedback to your brain. Finger will apply just enough pressure to operate the switch, and at the critical point, will move the switch fast enough to avoid arcing.
10.4p is a better price than what is available to me - 12.6p at the moment, rising to nearly 15p at the end of this month..
You are correct that, with an immersion heater, all the energy from the electricity goes into the water, while with a gas boiler, some is wasted in heating the boiler itself and the water in the closed loop, but, unless you are nocturnal, there are considerable losses from the cylinder before you use the hot water many hours later.

 

[James]

If you can get 10p per kw/h on gas or electric, it is likely to be about 20% cheeper to heat by electricity.
electric heaters are close to 100% efficient
gas heaters are at best 80 to 90% efficient
however, if you heat your water at night using electricity, bear in mind that your 100% efficiency will be brought down by the fact that some heat is lost before the water is used. Insulation and time spent as stored heat make huge differences to your theoretical savings.