DHW dual stat

[Hairymelon]

I have been given this dual stat to replace one on an unvented cylinder. The original type( with an earth connection,) is no longer available.
This one does not show an earth and nor can I find an earth terminal. Can I assume it’s double insulated and ok to install ?

 

[JohnW2]

I have been given this dual stat to replace one on an unvented cylinder. The original type( with an earth connection,) is no longer available. This one does not show an earth and nor can I find an earth terminal. Can I assume it’s double insulated and ok to install ?

Does it have any exposed (i.e. touchable) metal parts? If not, there's nothing you could earth.

Kind Regards, John

 

[Hairymelon]

Thanks John , what I am uneasy about is the 2 copper bulbs pushed into a metal tube to sense the water temperature
, somehow I can’t believe that they could never become live

 

[Hairymelon]

Sorry if it’s upside down

 

[JohnW2]

Thanks John , what I am uneasy about is the 2 copper bulbs pushed into a metal tube to sense the water temperature, somehow I can’t believe that they could never become live

Firstly, apologies, it did not sink in to my brain that you were talking about a cylinder stat - I was was probably thinking that it was a wall one!

I suppose that whether or not those bulbs could ever become live depends on how the device is designed and constructed (and what is inside the bulbs). Even if they could and did become live, you wouldn't be able to touch them, so the only real risk would presumably be that they could touch the tubes - but they presumably would almost certainly will be earthed (via the cylinder) - so that, in practice, if the bulbs ever did become live AND touch the tube they would trip something. It is, however, perhaps a little odd that there is not provision for earthing the bulbs.

Others may have other thoughts.

Kind Regards, John

 

[EFLImpudence]

You are supposed to be qualified (G3) to work on unvented systems.

 

[Hairymelon]

Often I come across unvented cylinders without the immersion heater connected and without an earthed cylinder stat one would be relying on the earth bonding presumably (I am not an electrician) The stat ,made by cotherm, has nothing in writing to tell me if it’s ok to do away with the existing earth.
I was hoping a professional electrician may have wired one up perhaps armed with more detailed instructions via a cylinder manufacturers literature

 

[Hairymelon]

You are supposed to be qualified (G3) to work on unvented systems.

What’s that got to do with it?

 

[EFLImpudence]

Everything ?

 

[Hairymelon]

Do electricians have to have g3 to wire an unvented cylinder?

 

[Deleted member 267285]

Is it this one? https://www.cotherm.co.uk/solutions/encased-thermostats/dcr-dual-control-and-regulation/

https://www.cotherm.co.uk/wp-content/uploads/2015/11/DCR.pdf

It might be that you have to have G3, unsure though. Any sign of this symbol:

 

[JohnW2]

You are supposed to be qualified (G3) to work on unvented systems.

Does that apply to the electrics as well as the plumbing?

Kind Regards, John

 

[flameport]

G3 is a section of the Building Regulations.
Installing an unvented cylinder is notifiable work.

Some people might go on a G3 course so they can register with a competent persons scheme to notify such things more cheaply that direct to building control.
Otherwise it should be notified to BC directly.

Repairs and maintenance of unvented cylinders is not notifiable.

All of the above should be done by competent persons.
Attending the one day G3 course and obtaining the piece of paper that said you passed could be useful in suggesting an individual was competent.

 

[Hairymelon]

Is it this one? https://www.cotherm.co.uk/solutions/encased-thermostats/dcr-dual-control-and-regulation/

https://www.cotherm.co.uk/wp-content/uploads/2015/11/DCR.pdf

It might be that you have to have G3, unsure though. Any sign of this symbol:
View attachment 230444

Yes that’s the one. No symbol that I could see

 

[JohnW2]

Yes that’s the one. No symbol that I could see

As I said before ...

... I suppose that whether or not those bulbs could ever become live depends on how the device is designed and constructed (and what is inside the bulbs)....

Whilst it still to some extent 'depends' (on the design), that description says that each of the bulbs is fluid-filled and operate a bellows - so, although they are copper, there's really no reason why they should go anywhere near anything electrical, so there is probably no significant risk that they would/could ever become live..

Kind Regards, John