Remote switch for immersion heater on ring

[DanAir]

I have two hot water cylinders, each with a 3kw immersion heater that is used only very occasionally. At present they are wired to the upstairs ring (I know this is not the best way) and the only way to switch them on is to climb into the loft and push the switches on the plugs. I'm not planning to do any work myself unless I'm pretty confident that I understand it, so no need to warn me off, but I was wondering what I could do to add some remote switching so I could turn them on from downstairs next to the boiler. Routing the cables isn't a problem but how would I wire it? Thanks all...

 

[mikeyd]

Whatever your solution please don't let it involve having a 3kW device plugged in and switched on for long periods of time in your loft. I know in theory it should be OK but I recently had a plug (on a fan heater) melt into one of my sockets , it was only because I needed to move the heater I noticed the plug was fused into the socket and when I removed and smashed the socket apart for a look it wasn't a pretty sight. The socket obviously hadn't been giving a good connection to the plug pins but there was nothing to suggest anything was wrong. We only ever used to run the heater for maximum of an hour or so at a time so I hate to think what would have happened if I'd ever accidently left it on.

PS please don't tell me they are plugged into one double socket.

 

[comms]

Change sockets for Fused spurs, from load terminals of spurs run cable down stairs to 20amp double pole switches with neons, run cable from load terminals of 20amp switches back up to cylinders and terminate into flex outlet, run flex from here to cylinders.

 

[DanAir]

Change sockets for Fused spurs

Can you clarify - do you mean change the sockets for FCUs that sit on the ring or do I run a spur off the existing socket into an FCU?

 

[comms]

Change sockets for Fused spurs

Can you clarify - do you mean change the sockets for FCUs that sit on the ring or do I run a spur off the existing socket into an FCU?

Upto you but I'd change one socket for one of these

http://www.tlc-direct.co.uk/Images/Products/size_3/MKK2025.JPG

and install two of these on the ring, and take T/E from load terminals downstairs.

http://www.tlc-direct.co.uk/Images/Products/size_3/MKK337.JPG

Then downstairs install two of these

http://www.tlc-direct.co.uk/Products/MKK5423.html

And back upstairs heat flex to the cylinders from two of these

http://www.tlc-direct.co.uk/Main_In...Mk_Accessories/Flex_Outlets_Plates/index.html

 

[Space cat]

From the loft all the way downstairs then all the way back up again is a lot of cable. Moreover, as you're probably aware already, if both heaters are on together you're using up most of the capacity of your upstairs ring. Do you have any spare space in your CU? It would be better to put your two heaters on their own little ring from their own breaker - and better still to put them on radials with a breaker each.

 

[Taylortwocities]

Immersion heaters should not be on a ring final socket in any case.
If you have space in your consumer unit they should EACH have their own dedicated circuit each with a 16A or 20A breaker.

If you like then you could turn the immersions on by using the breakers in the consumer unit.

 

[DanAir]

Thanks for the responses. Unfortunately there's no room on the CU which is probably why they were installed on the upstairs ring. Either way I barely use them, maybe once every couple of months, so I'm reluctant to undertake extensive work like replacing the CU.

and better still to put them on radials with a breaker each.

Incidentally, for my education, why is this the case? If the MCB/fuse is of a suitable rating what is the benefit of splitting it?

 

[Space cat]

An immersion heater is a large load which, in some cases, is on for extended periods. Putting one on a ring significantly reduces the ring's capacity and so it's best practice to give them their own circuit. In your case you say they are rarely used but I have to ask on question: When they are used are they both used at once? A ring is only good for about 7kW in total.

You might consider putting one of them onto the downstairs ring instead but it's not that simple. Downstairs rings tend to be heavily used. What's on yours: washing machine, tumble drier, electric oven? Two on a lightly loaded upstairs ring or one up, one down? The choice is yours.

 

[DanAir]

All things considered I think I'd keep them both on upstairs ring as there are no large load appliances at all upstairs as opposed to downstairs where there are two dishwashers, a washing machine, a dryer, kettle, toaster, electric oven, fridge freezer, freezer etc. etc.

From the loft all the way downstairs then all the way back up again is a lot of cable.

This is a very good point; as an estimate I'd say it's a run of about 15 metres, which up and down for two appliances would amount to 60m of cable. Not a showstopper but nevertheless inconvenient. I may compromise by putting the switches in the a cupboard in the main bedroom which is directly below.

 

[Space cat]

I may compromise by putting the switches in the a cupboard in the main bedroom which is directly below.

As an added bonus, this keeps the switches on the same floor as the ring from which they get their power.

 

[Steve]

A good way to free up a slot in your CU is to take the lighting circuits out of the CU, wire them to two fused connection units (as above) and run the 2 FCUs off a single 16 amp radial. This frees up one spare way

 

[Space cat]

This frees up one spare way

And one spare way is all you need for a ring with two FCUs on it for your heaters. You'll be using most of its capacity when the heaters are on - just as you will on the upstairs ring - but if there are no sockets on it there's no problem.

PS: You can even add extra FCUs for low power stuff: door bells, alarms, outside lights, etc, etc.

 

[tim west]

If determined not to put right the installation then this kit will do what you want.

Remote control Appliance module

And this

Remote

 

[DanAir]

All great ideas thanks everyone.

Tim: From a quick look at that device it looks really good except that I don't think you can tell from the remote whether the appliance is on or off. I think I'd get really paranoid that the remote hadn't worked or something like that and I'd have 6kw drain on my electrical supply (or ~50p/hour). Are you aware of any similar device that does send feedback re. whether the device is on or off?