Water heater control

[Dwayne]

Hi there. 
I want to use a Shelly 1 (or other suitable unit) to control my electric water heater (boiler).  This 100Ltr boiler is presently connected to a 32A supply, over a 240v fused spur switch. 
 

I would like to know if I can connect the Shelly1 to this switch in order to control the boiler on/off remotely. 
 

I know the Shelly1 is 16A rated, but in this scenario is it incompatible?  If so, is there any other Shelly device I could use for this?

thanks

dwayne

 

 

[tvbshelly]

Do you know the exact electrical connection values of the boiler, i.e. how many amps the heating element requires at most?
The way it is currently fused, you have to assume that more than 16A is used as power. Then you must not use a Shelly under any circumstances; Shellys are only available up to a maximum of 16A.

It is best to use a contactor for such loads.

The contactor is then switched with a Shelly. In this case, 16A is sufficient for the Shelly, or you can also use smaller Shellys.

If you switch a contactor with a Shelly, it can be useful to add an RC snubber here because the relay in the contactor is an inductive load.

Edited August 22 by tvbshelly

[Dwayne]

Thank you TVBShelly 

the boiler actually has two heating elements, so while I am unsure what the amperage load is I’m pretty sure it could go over the 16A.

Could I perhaps add a Shelly EM behind the 32A breaker that supplies the boiler?  Then control that device remotely to shut off power to the boiler over wifi?

Thanks for taking the time 👍

 

Edited August 23 by Dwayne

[tvbshelly]

1 hour ago, Dwayne said:

Could I perhaps add a Shelly EM behind the 32A breaker that supplies the boiler?

Yes, you can do that. With a Shelly EM, the current is measured with a current transformer (CT). These transformers can safely measure significantly higher currents: 50A or 120A; in your case, 50A should be sufficient. 

1 hour ago, Dwayne said:

Then control that device remotely to shut off power to the boiler over wifi?

What exactly is "that device"? It is important that the relay / contactor / etc. used for switching can also withstand currents greater than 16A.

A Shelly EM has an integrated relay with a rated current of 2A per output for contactor control.

If you are not sure what is a safe and permitted solution, you can also ask a local electrician to be on the safe side.

Edited August 23 by tvbshelly