adding a timer to the immersion heater

shabbyroad

Ok, time has come to fit a timer to the immersion heater.

this is what I've got :
digital timer with straightforward mains in (Live,Neutral, Earth) and appliance out (LNE).
seems straightforward

the immersion has neutral & earth as well as 2 live wires (one for 'bath' and the other for 'sink'

the existing switch has on-off and bath-sink

how exactly should I wire this ?
have googled and looked on some sites but no luck - don't know any electricians.

Victor

It isn't a job I'd do DIY as the current drawn by immersions + the heating cooling affecting connections makes them a greater fire hazard. Add DIY to that - I'm not sure if your insurer would approve.

You could add it to "Bath" as it, rather than "Sink" is the real consumer of electricty. As your time commitment is fixed (to say 3hours/day), you remove the risk of leaving it on to "Bath" for the entire day / weekend / fortnight's holiday.

I also think an analouge timer, being simpler to operate / understand, would be a better option than digital.

Borzoi

Wiring the immersion is no great trick, but it is complicated by the fact that you can have dual coil types. Is this what you have, or are there two totally seperate elements, ie one high, the Sink coil, and one low, the Bath coil. Dual type has both of these in one unit.

Sound like the latter to me, in which case I would put the controller between the live output from your standard swithc, and the coil, this will mean that the digital controller only does the sink. No real need to wire the nuetral, but I'd do the earth for safety's sake.

The real worry would be is the digital controller capable/rated of switching the immersion load. IIRC a typical immersion is 3-4kW, I have no idea what your controller is capable of safely switching. You need to check both ratings to be sure you're okay. Don't take any chances here.

Otherwise it's straight forward.

BTW I'm not a RECI electrician but I do design control circuits and I have wired my own immersion, so it is at your own risk:D there are a couple of sparks here on boards who'll probably be along shortly with contrary advice:rolleyes:

shabbyroad

thanks for the feedback.
the timer is specifically designed/rated for immersion heaters
The immersion is a dual-coil (one unit two elements).

Now that I've slept on it I realise that what I need to do is put the timer after the On-Off switch and before the appliance.
This means that I can completely over-ride the timer if necessary.

The bath-sink switch can still operate as normal.

WIll have another look at it all when I've had some coffee..... and spoken to someone in the hardware store

komodosp

Hmm... I have a fourth wire between the switch and the appliance earth, live neutral and... Black? I cut the cable and wired up the timer between the normal switch and the immersion. Presume this black one controls whether it's bath or sink, so I just connected it back together. Was this the right thing to do? It seems the timer works, but even though I had the switch on bath it only heated a small amount of water as if it was on sink...

Buford T Justice

komodosp wrote: »

Hmm... I have a fourth wire between the switch and the appliance earth, live neutral and... Black? I cut the cable and wired up the timer between the normal switch and the immersion. Presume this black one controls whether it's bath or sink, so I just connected it back together. Was this the right thing to do? It seems the timer works, but even though I had the switch on bath it only heated a small amount of water as if it was on sink...

Two wires, brown and black. One serves the sink element and one the bath. Not sure which is which though,

CBYR1983

I had an electrician put one in for me in exchange for boarding after the 2009 All Ireland Final! A Kerryman.

I had purchased a mechanical flash immermat timer.

He put it in before the immersion switch.

That way I can still adjust bath/sink as required. If the timer switch is off, no power to immersion.

So the original immersion switch is left permanently on.

Mine is quite simple - there is no thermostat on the cylinder.

coylemj

CBYR1983 wrote: »

I had an electrician put one in for me in exchange for boarding after the 2009 All Ireland Final! A Kerryman.

I had purchased a mechanical flash immermat timer.

He put it in before the immersion switch.

That way I can still adjust bath/sink as required. If the timer switch is off, no power to immersion.

So the original immersion switch is left permanently on.

Mine is quite simple - there is no thermostat on the cylinder.

Unless the timer can control two separate channels that is the only way to do it - put the timer between the mains feed and the Sink/Bath switch. If the timer can control two channels (one earth out, one neutral out and two live outs) then you will need to remove the Sink/Bath switch completely and replace it with the timer.

yoshytoshy

Be careful you don't mix up the neutral and one of the lives. I had an emergency call before christmas where the cylinder was pouring water down through the house.
The thermostat wasn't working because the neutral and bath were mixed up and the soldering melted on the immersion and started to leak.

Very dangerous.

M cebee

usually a timer before the immersion switch anyhow-that's all there is to it

-it's not allowed to 'replace' an immersion switch with a digital timer

M cebee

yoshytoshy wrote: »

Be careful you don't mix up the neutral and one of the lives. I had an emergency call before christmas where the cylinder was pouring water down through the house.
The thermostat wasn't working because the neutral and bath were mixed up and the soldering melted on the immersion and started to leak.

Very dangerous.

you'd only have a kilowatt of heat when you series the 2 elements

but the stat is bypassed alright

yoshytoshy

M cebee wrote: »

you'd only have a kilowatt of heat when you series the 2 elements

but the stat is bypassed alright

The solder melted and the water was coming through the element connection. The person had left the immersion on by mistake when they went on holiday and came back to a wet house.
Maybe because the power was running through it for so long ,it overheated so much.

Wasn't my fault though ,a builder had done the work:(

sohappy

dont mean to hijack the thread.. but why is that immersion switches and timers are nearly always inside the hot press, would it not be more user friendly if these were mounted on the wall outside,(where you could see them) also if a timer or switch is faulty and goes on fire would it not be safer on the wall outside rather than inside with a load of clothes and bed linnen.

meercat

sohappy wrote: »

dont mean to hijack the thread.. but why is that immersion switches and timers are nearly always inside the hot press, would it not be more user friendly if these were mounted on the wall outside,(where you could see them) also if a timer or switch is faulty and goes on fire would it not be safer on the wall outside rather than inside with a load of clothes and bed linnen.

youre quite right
current regulations prohibit installation of switches inside hotpress

M cebee

ya- they're fitted outside these days