Help with wiring zwave switch for water heater (240V)

[Mathias Koerber]

Moin,

I hope this is a suitable group for this kind of question. If no, suggestions are welcome.

I'd like to automate our storage/tank water heater using some home automation system using zWave.

Local power is 240V 50Hz

The Water Heater is rated 220V-240V 2.5-3kW

(which in my calculations may end up just above 13A)

Originally, the water header was just connected directly to the incoming power supply via a 2-throw wall switch (for both the L and N wires, ground connected through inside the switch housing.

I was planning to use a Fibaro FGS-213 switch for this

It is rated at 8A tops, so it cannot be used with the heater as load directly

So I got a contactor:

Schneider TeSys LC1K09 10M7

which is rated:

| [Ie] rated operational current | 9 A AC AC-3 for power circuit at

[Andy Burns]

You talked about double pole switching (i.e. disconnect live and neutral) but your diagram shows a permanent neutral to the heater?

You show a live going to contact 13 and a neutral going to contact 14, that thing is going to go *BANG* if you ever get the contactor to turn on.

Thankfully it will never turn on (unless you operate the mechanical interlock) because you don't show any connections to the contactor coil on A1/A2

A serious rethink required ...

[Mathias Koerber]

L goes to L1 on the contactor and from there from T1 to the heater's L N goes to L3 on the contactor and from there from T3 to the header's N

Both are switched when the 13/14 trigger connection has voltage applied..

That connection is the contactor

According to the Data Sheet, A1/A2 are aux (they also switch along with L1T1,L2T2,L3T3 but it is used to either just show a low-voltage LED light when switched on, or to be able to trigger another daisy-chained contactor etc (in which case these would go to 13/14 on the second contactor.

[Mathias Koerber]

Oops. I see what you mean. I confused the A1/A2 and 13/14 aux contacts.

But the main point stays. the L and N from the supply are not directly connected to the heater, but will get those wires switched only when the signal from the Fibaro provides voltage to A1/A2...

I am updat> >>

[Andy Burns]

That is what I would expect, except your diagram doesn't show any connection to L3/T3 at all, have you posted the wrong dropbox link?

I found info for the LC1K-09-10-G7 which I think is just a different coil voltage to the M7?

Doesn't that show coil on A1/A3 and 13/14 as aux N/O contacts?

[Andy Burns]

At least it was only on paper :-)

The live is switched through the fibaro/contactor (I didn't get as far as checking what the contact letters mean on the fibaro) but the neutral is shown as being permanently connected from the blue diamond

I'll have another look when you've re-drawn it ...

[Tim Watts]

Totally :)

Plenty of headroom with this module:

plus it will measure power consumption as a bonus.

[Mathias Koerber]

Andy,

yes, it seems the link was bad.

here is a new one:

I hope that this one works

M

[Andy Burns]

Yes that wiring looks correct, including the z-wave contacts.

Is this in the UK? A dedicated radial or on a ring circuit? What rating fuse or MCB?

You might want the live feed to the z-wave module to be fused down lower than the heater circuit as a whole ... [checking] ... the manual says

10A max.

[Mathias Koerber]

Dedicated Radial on it's own MCB.. so hat should not be a problem

Thanks. One more question. In my current design, I have (other than the contactor) no load on the load circuit opened by the Fibaro switch. Would that be a problem, electrically? Should I maybe add a smallish lamp/LED for it to drive?

And yes I understand that the Fibaro switch won't measure any useful power usage (other than times on/off) with or without that extra load. The solution with the heavy duty switch Tim suggested may be better, if I can find one here (Singapore)

[Tim Watts]

I have the Fibaro DIn modules - they don't care if they have zero load. I have a couple on circuits that do not yet have lights.