Unvented Cylinder stats s-plan

[Spoony]

Hi all,
Please can I get some help. I’m currently wiring up 20 unvented cylinders at the moment. They are all part of an S-plan which is fine. The problem I’m having is with the two in-built stats on the immersion tank. One stat is a high limit cut out stat and the other is an Adjustable.
I believe the high limit stat should be wired as normally closed but I’m not sure about the adjustable one. Should the adjustable stat be normally open or closed?
Stat documentation added

 

[littlespark]

Both normally closed.
You want current to flow through, heating the elements until it reaches the desired temperature, when it then opens.

 

[Spoony]

I thought as much. Thanks for the reply

 

[LankyWill]

They’re wired in series, most have the link pre wired others don’t.

 

[Spoony]

Yeh I’ve wired them in series. High limit stat first. These two stats don’t have an internal link so I’ve wired them back to a joint box. The tanks haven’t been filled yet so the adjustable stat is clicking at 20 degrees (internal temp of empty tank). So just to confirm I want the circuit to flow until it hits its click. Not afterwards.

 

[Taylortwocities]

Yes, wired in series with the DHW control. This is essential to prevent the cylinder boiling in the event of a fault.

Thought you had to be G3 qualified to do this work?

 

[Spoony]

I think the G3 qualification your speaking off only applies to plumbers.

 

[Taylortwocities]

Ahh, probably.
I’d still be concerned that our OP doesn’t know this basic detail of unvented cylinder wiring.
Not just one cylinder, but he’s installing 20.

 

[Taylortwocities]

...

 

[Sparkie30]

You need G3 if you installing a unvented indirect cylinder.

 

[Leesparkykent]

You don’t need a g3 cert to do the wiring. The person who does the g3 cert will check it over before commissioning/signing it off.