Options for Smart Timers/Switches for Immersion Heaters & Storage Heaters (potential IFTTT)?

ch_152

Been a while, but now it's getting chilly again I'm looking at installing a smart switch for my night storage heater, and at the same time considering doing similar for my immersion (which is just on a manual timeclock).

I've read a number of reviews/posts about some of these online and people have mentioned some melting/burning out etc. and obviously I don't want to burn my house down. So looking for tried and tested

I might dive into IFTTT so something with that capability would be a bonus, but I'm not sure (Agile isn't looking so great as of right now, but that's a discussion for another thread).

I understand my current 3kW immersion heater and 3.4kW storage heaters probably need units rated to at least 16A.



A few I've seen recommended are:

https://amzn.eu/d/7induLc  (rated up to 20A. I know some here have used these in the past)

https://www.heatingcontrolsonline.co.uk/optimium-wifi-immersion-heater-timer.html (says it's only good for 3kW immersion heaters, but it is rated up to 16A)

https://www.airconcentre.co.uk/products/timeguard-wi-fi-controlled-fused-spur-tuya-edition-fstwifitu?variant=39685254054021 (this was a fan favourite for a while for immersion heaters, but only rated up to 13A)

https://amzn.eu/d/iCJouXB (this is similar to the above, 13A, and seems well reviewed)




Cheers

Bendo

I'm using a couple of the timeguard ones for 2 3 kW immersions. No issues so far. Timeguard are a reputable brand and say they are ok for a 3kW load.

Seen many reports of burnt out shelly and sonoff relays that despite claiming to be rated at 20A, have clearly failed someway betore.

Reed_Richards

I have a Timeguard FSTWiFi to program my immersion heater.  I've used it for about four years now without any problems, although I only use it in summer.

FreeBear

Bendo said: Seen many reports of burnt out shelly and sonoff relays that despite claiming to be rated at 20A, have clearly failed someway betore.

I've got a bunch of Chinese made smart switches that contain 10A relays - Would never, ever trust them to switch that sort of current. Maybe 4-5A max.

Also have a couple of Sonoff Basics (rated at 10A), again, I would only trust them up to 4-5A. That aside, I do like the Sonoff products as they are easy to hack and can be flashed with alternative firmware. Tuya based products, another story, so I avoid them like the plaque.

The Sonoff POWR320D is rated at 20A, which is probably the maximum rating of the relay. Being conservative, I'd be reluctant to switch more than 10-12A with one. Unless you need the current monitoring abilities of the POWR320D, I'd go for a basic Shelly or Sonoff to switch a suitably rated contactor.

Scrounger

I'm using a Tapo smart plug to control a 25A contactor for my immersion (summertime only):

http://www.amazon.co.uk/Modular-Contactor-TOCT1-Reliable-Performance/dp/B0DGXGCFFV

Mounted in Wylex enclosure:

http://www.amazon.co.uk/Insulated-Electrical-Circuit-Breaker-Enclosure/dp/B01NCZHMWD


Scrounger

ch_152

Thanks for the replies all.

The Timeguard seems like a fairly popular choice for immersion heaters.


@FreeBear the switch/contactor combo is something I'd read about before but don't quite understand how it works.

My understanding is that the contactor is basically a switch, the state of which is controlled by the presence of a voltage. The control voltage to "activate" the contactor is provided via the smart switch (sonoff, shelly - you'd call this a "relay"?). So the big current is only drawn through the contactor.

The reason this is preferable is because you trust the current rating of a contactor over the Sonoff/timeguard etc. that I sent earlier?

Is that right? I don't really understand how this is wired - where does the power come from for the smart switch?



@Scrounger I don't suppose you'd be able to send me a photo of how it's connected up inside the enclosure and then this might make sense to me. I actually have a bunch of Tapo smart plugs knocking about.

Cheers

Scot_39

The contactor can essentially be a "dumb unit" - you supply a low voltage / low ampage switch signal from a timer - it switches the full load.

If your on E7 at the moment - with a current smart meter or a digital meter - that could be a 5 port meter - it has the timer (intelligence) - and the normally 100A contactor (live restricted output wire switch) built in.

Or you could be as some here would put it less lucky - and have a four port meter - with built in timer - driving a control singal on a very low amp output - to a contactor.  And the contactor switches the 100A restricted consumer unit tail.

This user has a 4 port set-up - with a similar (same) Proteus contactor module as my install - switching his restricted time supply consumer unit live tail - the RHS block - LL in (from meter via Henley) live 24/7 - LLL out - restricted time only

https://forums.moneysavingexpert.com/discussion/comment/78172483/#Comment_78172483

FreeBear

ch_152 said: My understanding is that the contactor is basically a switch, the state of which is controlled by the presence of a voltage. The control voltage to "activate" the contactor is provided via the smart switch (sonoff, shelly - you'd call this a "relay"?). So the big current is only drawn through the contactor.

The reason this is preferable is because you trust the current rating of a contactor over the Sonoff/timeguard etc. that I sent earlier?

Is that right? I don't really understand how this is wired - where does the power come from for the smart switch?

A contactor is little more than a relay on steroids. The bits of metal doing the switching are much beefier that those found in a relay, and it has a bigger air gap when off (important when it comes to contacts arcing). If you use a contactor with a 240Vac coil, it would be powered by the Sonoff/Shelly, and the live side of the contact wired to the mains (preferably via an isolation switch).

If you have any doubts over how to wire this sort of thing up, it would probably be best to call an electrician in, preferably one that has some knowledge of industrial control systems.

Chrysalis

I am guessing this needs rewiring, I might pay the expense of buying one of these units and then see if I can come to agreement with my LL for him to pay one of his staff to fit it.  As I think adding a timer to my dumb immersion would be nice.

Reed_Richards

Surely a solid state relay would be a better switching option than something with switches that actually move (so you have to worry about air gaps and arcing)?  You can get these for 32 A or more and "zero crossing" so the switch takes place at the instant when the AC current is zero.

Scrounger

Reed_Richards said:

Surely a solid state relay would be a better switching option than something with switches that actually move (so you have to worry about air gaps and arcing)?  You can get these for 32 A or more and "zero crossing" so the switch takes place at the instant when the AC current is zero.

Although that seems a logical solution, I don't know of any domestic time switch, smart switch or controller that uses a solid state relay even for 13A.

There must be a reason for this; could be cost, safety issues or reliability.


Scrounger