Unvented water system in Daughter's house

[razbaz]

Hi , I'm new to the forum but would welcome your thoughts on this.

My Daughter's has moved into a property that has a recently fitted Unvented Water System. I had little knowledge of these but was surprised there was not a timer switch fitted.

The property is all electric and the water system runs on Economy 7.

At the moment, they are switching it on and off when needed ( but the switch is in the tank's cupboard,awkwardly up out of sight!--see pics)

My questions are: Can it be left on? ( and does it have an internal cut off or other) or do we add a timer switch that can be placed on the wall outside the cupboard?

Also, how would the timer switch connect to the switches as shown/

Many thanks for all help/advice.

[SteamyTea]

The E7 time window is what switches it on and off.  So leave it on.

You may be able to reduce the temperature on the thermostat.  I dropped mine down to below 45°C.  This reduces standing losses.

 

There may be a secondary immersion heater in it, that is best left switched off.  They are there for emergencies when all the water, heater on the night rate, has been moved (used).

[ProDave]

I would just add, leave the switch that leads to the BOTTOM of the 2 heaters on all the time.  That will heat up the whole tank over night on the cheap E7 rate.

 

Only turn on the switch to the top heater as a boost if you have used all your hot water and need more before the next overnight charge up.  Very often there is another, more accessible switch for this function, sometimes even a boost timer.

[TonyT]

Is that one twin and earth feeding both immersions?

[razbaz]

  On 24/09/2021 at 14:26, TonyT said:

Is that one twin and earth feeding both immersions?

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The white cable? I thInk so, I've asked my daughter to have a look.

Edited September 24, 2021 by razbaz

[Nickfromwales]

  On 24/09/2021 at 14:26, TonyT said:

Is that one twin and earth feeding both immersions?

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Might be a 4mm2, but yes, not good if just a 2.5mm2 on a radial cct. 

@razbaz, can you show a pic of the fuse that services these two switches? Close up so we can see details, plus a shot of the fuse-board ( aka CU ( Consumer Unit )). Thanks. 

[ProDave]

If that IS one cable feeding both, then it cannot operate the normal way with one being connected to the switched off peak feed and the other on a 24/7 feed.

 

So yes please photos of ALL consumer units and anything that looks even remotely like a timer or boost controller.

[SteamyTea]

Pipes should be insulated as well.

 

Who did this installation?

[Nickfromwales]

  On 24/09/2021 at 21:29, SteamyTea said:

Pipes should be insulated as well.

 

Who did this installation?

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Cold feed and PRV ( D1 > D2 ) visible, so not needing insulating. @razbaz, is the pipe coming out of the top insulated? Big losses from that so best you do that if not.

[MikeSharp01]

  On 24/09/2021 at 14:17, SteamyTea said:

The E7 time window is what switches it on and off. 

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How if it is fed from a ring without a timer? Looks like the call for more info is pressing.

[SteamyTea]

  On 25/09/2021 at 06:25, MikeSharp01 said:

How if it is fed from a ring without a timer? Looks like the call for more info is pressing

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This is the great mystery.

Usually there is one dedicated circuit from the E7 side of the consumer unit to the bottom immersion element, and a second circuit, which may or may not be a dedicated circuit, to the upper element.  That secondary 'boost' circuit comes from the 'day' side of the consumer unit.

My house has two separate consumer units. The Day and the Night, there is a radio switch in the meter box that switches the night circuit on and off, and I assume, though never actually checked, allows the import meter to know it is night and log all usage to the cheaper rate.