immersion wiring

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15 Sep 2009
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United Kingdom
hi all,
i have a hot water cylinder with twin immersion (side entry) both 11" bottom for off peak, top for boost,and i would like to add horstmann timer,as the top immersion is not in use how difficult is it to add a timer to the circuit,also what size flex should be used from 20amp double pole switch to thermostats 1.5mm 0r 2.5mm,any advice would be appreciated
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devil your post doesn't make much sense to me, maybe I've been on the PC too much today (a beer is due!),

A double emmersion tends to have 1 switch, but like this:-


When you suggest you want a timer and stat do you mean for CH hot water or for electrical water via the element ?
Often, cylinders with two elements would have two supplies to it.

One supply to the bottom element would normally be fed from an off peak supply to heat the entire cylinder over night with cheap(er) electricity.

The top element would be supplied from the normal peak supply to allow you to top up the hot water. As the element is near the top, it heats the water quicker too as it will only heat the top third or so of the tank.

Do you have a dual rate electricity supply?
What are you thinking of connecting to the horstmann timer ? Both elements ?

Because if you were thinking of only connecting it to the top, to work as a timer I would think again. The mechanical horstmann timers are inflexible, and can't turn on a top element for a short period automatically at a set time.

You could however manually turn them on for a period of your choice. i.e 15 mins. upto 1 hour and automatically switch off.
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my old immersion setup had a dual element,but it had packed up,so ive purchased a new cylinder with two immersion holes at the side,the cylinder is now plumbed,the current circuit has a 15amp wire breaker(old type) my question is from the cu what should the wiring be,what should the dp switch be 13amp fcu or 20 amp?,and what should the size of heat resistant flex be 1.5mm or 2.5mm? can anyone specify what should be used

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