Double immersion hot water tank.

[Pauldicker]

Dear all,
Has anyone come accross a double immersion hot water tank. How did you supply it 2x16A circuits. Maybe a 32A circuit split into 2 with 2x 20A double pole switches. I have only come across singles before, so im trying to find the best solution as i only have 1 spare way at present.

 

[Nebu1a]

Do you mean a cylinder with an off peak and on peak element?
Bottom one usually supplied by the off peak consumer unit and top one is an on peak boost.

 

[Blissof89]

Bottom Immersion would generally be used for night time heating of water on cheaper rates. Top Immersion for boost.

They aren't suppose to run simultaneously, just get an Immersion timeclock with boost function.

 

[Pauldicker]

No its some horizontal thing (not a plumber) like a unvented or something. But has an immersion at either end.

 

[Pauldicker]

Bottom Immersion would generally be used for night time heating of water on cheaper rates. Top Immersion for boost.

They aren't suppose to run simultaneously, just get an Immersion timeclock with boost function.

It has 2 3kw immersions i.e boiler does most of the time but incase of breakdown immersion will provide hot water.

 

[Nebu1a]

Never come across a horizontal cylinder before but I would have thought it would be the same as a conventional cylinder. Have you googled the MIs?

 

[Pauldicker]

Never come across a horizontal cylinder before but I would have thought it would be the same as a conventional cylinder. Have you googled the MIs?

Mi just says 2 3kw immersions.

 

[Nebu1a]

I would think one element is for off peak. You could wire 2x 16amp circuits but only connect one. Do they have E7, E10?

 

[Blissof89]

I don't see a problem with running a 32A radial to feed both if they are designed to operate together. Still a dedicated circuit for a piece of equipment imo.

I would prob go for FCU's rather than 20A DP tho, if you are using 1.5mm flex to feed the immersions.

 

[Pauldicker]

I don't see a problem with running a 32A radial to feed both if they are designed to operate together. Still a dedicated circuit for a piece of equipment imo.

I would prob go for FCU's rather than 20A DP tho, if you are using 1.5mm flex to feed the immersions.

 

[Pauldicker]

Thanks.
Will individual 13A sfc suffice due to demand. And will two 2.5mm t&e to each sfc out of the 32 be permitted.

 

[Blissof89]

And will two 2.5mm t&e to each sfc out of the 32 be permitted.

No. and the fact you have to ask tells me you should probably get someone qualified to install for you.

 

[Pauldicker]

No. and the fact you have to ask tells me you should probably get someone qualified to install for you.

Really!

 

[Blissof89]

Yes, really.

Ib<In<Iz.

 

[Blissof89]

After reading again I'm not sure if you are suggesting running 1 T&E to each FCU from the same MCB or ' doubling up' the conductors to each FCU.

The first is a definite no.

Doubling up conductors is allowed in some situations but in this one i would say it is bad practice, plus terminating 4 x 2.5mm conductors into a MCB or FCU ain't gonna be pretty.

Just get some bigger cable.

 

[Pauldicker]

Im after ideas. I was simply asking if i could have run two radials from one mcb to two fcu but it sounds like i may have to run a 4 or 6mm cable to i fcu and then 2.5 from that to a second.

 

[westward10]

Run a radial to a small consumer unit then two 16A radials.

 

[Deleted member 26818]

I would run a 6mm2 cable to an adaptable box with some connector blocks, then two 2.5mm2 cables to two SFCUs.

 

[telectrix]

nothing wrong with feeding 2 x 13A SFCUs with a 32A circuit (4.0mm) and then feeding each element in 2.5mm.

 

[Wilko]

These 2 element ones do get used in shops/restaurants to get more hot water volume. If it's that use, then it warrants a little over specing in my view as they will likely run them continuously. I'd like to put each on their own B16 / 2.5mm / isolator / 2.5mm heat flex if possible.