Direct boiler immersion wiring?

[Steve T]

I have got a direct boiler system with 2 immersions One top One at the bottom. One is on eco7 the other just on the mains.

How should these be wired in? should they both be straight to SFCU? or the non eco7 to a SFCU and Timer?

What should the stats be set at?

and if anyone has time could someone explain how is this supposed to work?
Am i right in thininking that the bottom one heats the water at night(Eco7) and the top works as a backup so if you use loads and comes on when the stat is triggered by the cold water rising.

So in effect the bottom does all the work and the top is only there to provide a boost if you use allot of hot water.

Thanks
Steve

 

[kai]

What power rating are the immersions?

If they are the normal 3kW ones, they will be wired to two sets of (min 2.5.sq.mm) radials running from two B16 Breakers through two 13amp DP switched fuse-connection units in the cylinder cupboard, one per element.

The lower element is fed from the economy seven consumer unit, and the top element is fed from the standard consumer unit.

It may be handy to also route the upper "Boost Element" through a 20amp switch marked water heater, located on the landing or hall, so that you can readily see whether the boost is being used, better still wire in an ecoomy seven boost control to drive the top element - best sited in the hall or landing etc.

Check that the earth bonding is up to date and correctly installed too.