Wiring two immersions

[Alex.]

Hello

I would like to have a bigger hot water tank, and I thought it would be handy to have one of those that have an immersion low down for the main heating plus another higher up to provide a small boost if needed.

Thing is there's only one cable to the tank position and it would be a serious (expensive) job to thread another through the house. Before I go and ask a teeth-sucking electrician, is there any way of using the one supply for both heaters? the existing cable is 2.5mm, from a 15A MCB.

Both heaters would never be needed at the same time, so maybe some kind of doohickey to switch one on and the other off is what I need?

Cheers

Alex.

 

[brightspark]

fit a changeover switch so u can only run one at any time basically a 20 amp double pole switch with a 20 amp 2way switch next to it on 2 gang plate. herehttp://www.ebay.co.uk/itm/like/130989131412?adgroupid=13585920426&hlpht=true&hlpv=2&rlsatarget=pla-131843279106&adtype=pla&ff3=1&lpid=122&poi=&ul_noapp=true&limghlpsr=true&ff19=0&googleloc=9046802&device=c&chn=ps&campaignid=207297426&crdt=0&ff12=67&ff11=ICEP3.0.0-L&ff14=122&viphx=1&ops=true&ff13=80

 

[MoreWellie]

a 3 position switch something like http://www.ebay.co.uk/itm/SCL-IC220...ver-Switch-3-Position-on-off-on-/172072507739 would do what you want as you could turn either heater on but not both

but not saying that specific one is a great deal just an example

 

[Wedg1e]

Pair of contactors and a thermostat?

 

[pedrobedro]

Can you get twin element immersion heaters with different length elements instead of fitting a new tank ?

 

[Alex.]

Thanks for all the suggestions, but I think there's a problem with the simple changeover switch ie I need a timer to tell the bottom element to come on during the off-peak hours, and if the bottom element feed is switched off the timer will go wrong.

Another idea - there's a ring main close to the HW tank, I don't suppose it's permitted to spur the boost immersion off that????

 

[octo0072000]

as Pedrobedro said
Here is a twin element immersion heater
with different length elements
so no need for another tank

http://www.advancedwater.co.uk/header-032-255-DUALCOPPER.html

 

[Dee J]

This is what you need:
https://www.tlc-direct.co.uk/Main_Index/Water_Heating_Index/Immersion_Heater_Timers/index.html
These timers will time the off peak main element and the boost button switches on the top element. All from one single supply - as long as that single supply is live all the time ie not from a dedicated off peak circuit.
HTH
Dee

 

[Alex.]

Dee
That's exactly what I need! Now when the electrician starts telling me I need a second supply I'll be able to look like I know what I'm talking about. Many thanks indeed.

Alex.

 

[brightspark]

just to add to the mix if u only have one emersion heater and its on off peak supply it will be only be fed between 12 ish and 7 in the morning so if u- use the economy seven switch with daytime boost -the feed cable will have to be transferred from night time supply to a 24 hour supply in your main db and the switch will time when it comes on off an evening nowts that simple