Shelly for Immersion Heater?

[EFLImpudence]

Without personal experience of them I don't know, however with the top switch on what is there to stop the heater being enabled?
With the bottom switch on what is there to stop the heater being enabled during cheap rate E7?

Oh, I don't know; what could it be nowadays? Electronics?

I presume they are designed to fulfil the purpose for which they are required.

 

[SUNRAY]

Oh, I don't know; what could it be nowadays? Electronics?

I presume they are designed to fulfil the purpose for which they are required.

I'm happy that some switching may take place when an event happens, such as the rate or the timeswitch changing but I'd be surprised if the output controlled by top switch didn't follow the 'ON' legend.
I don't know that as I have no experience of this particular device but an older version had 2 switches (for the 2 elements) marked OFF & TIMER for the off peak and the other marked TIMER & OFF & ON plus it had a additional ring on the mechanical timer settable for up to (I think) one hour to boost the offpeak element. Both elements worked during off peak periods if set to do so. As an aside to this my tenant reckoned it was more economical to run both elements during the off peak period than just one, I personally don't see why that should be the case though.
When I purchased the property I discovered the elements were wired to the wrong switch, IE only the bottom element would heat during peak times.

 

[Murdochcat]

All I can see you're offering is a timer on the boost. Unless you're suggesting that as the only method of control (one which I personally think would be a silly and unreasonable system) how does that switch anything off?

Hum,

This is for an air bnb. New resident arrives, pushes switch for upto 4 hours, heats up water then needs pushing again.

Then nobody can actually leave it on for any period, and if it’s pushed when the tank is nearly full of hot water it’ll only heat it until it’s up to temp

Used this precise system in customers installations in the past and they are happy

Horses for courses but leaving control of the hot water in the hands of an absent landlord strikes me as very short sighted