Smart Immersion Heater Timer Switch, 40A WIFI Smart Water Heater Timer Switch, Smart Wall Touch Boiler Switch with Alexa, Smart Life, Light Timer Switch, 8000W, (43mm deep box)

The old manually operated timer on my Emerson heater hadn’t worked for a year or more and I often had no hot water or I would turn it on then forget to turn it off for hours, which of course costs me money!I found this smart switch was easily installed only requiring four wires to be swapped from the old to the new switch.The Smart Home App is easily downloaded, however I already had it on my mobile, so the app found the new switch and installed it fast and I was good to go.Within the App I changed the switch name from 1 Gang Switch to Hot Water, I also set up a routine for the switch to turn on for one hour per day, which should provide me with the hot water I need in a day, but either using the App or voice command to Alexa, I now have the option to turn it one and off as or when I choose and for how long I choose, with Alexa managing the off time as instructed.Great device to add to your home network, especially for those of us without a Combe boiler who doesn’t use central heating in the summer months.

Nice modern design. Comes with a back box and it's just deep enough to fit in the cables but a bit fiddly. I'm glad I read the reviews so kudos to the guy who suggested buying something like Vimark Nylon Male Comp Gland 20mm 2 Pack (556VT) - Screwfix to tidy up the cable entry, and the guy who said you had to prise the glass front off with a screwdriver to access the screw holes to fit the plate to the back box (that had me stumped for a while). There's no earth terminal in the switch, so you need to connect the earths from the supply and the heater together. I happened to have a Wago 32A connector left over from another job so that was fine., you will need terminal strip or some similar method. The Smart Life app on the phone works ok and connects fine, but it took me a while to find how to schedule. I went into Scene added a scheduled switch-off at 6am and a scheduled switch on at 2am and this keeps our 200litre tank hot all day and uses 4 hours off peak electricity. You can also just tap the front glass plate to switch it on and off. Really please, and so far it's behaved itself, even a power cut didn't upset it, it just carried on from where it left off.

As another reviewer mentioned, mine also says "Max Load: 400W" on the box, but the device itself says "Max load: 40A" on the back (as well as saying it's a "Water Heater Switch"), so I think it's fine. I think they just use the same packaging for multiple different types of WiFi switches.Mine also came with the new deeper (43mm) back box, in a completely separate package within the outer packaging, but it's the wrong type really - it's one with round precut holes at the top and bottom of the box meant for conduit. And in my case, the screws with the unit itself didn't fit either this one or the standard UK backbox I bought to use instead (the screws are a bit too wide)I ended up having to use the screws that came with the backbox to attach the device to it instead, as they do fit, even though I think they were meant for attaching the backbox to the wall (but they seemed rather too long for that really anyway - the same length as the screws that were too wide). So the backbox is currently secured to the wall with some strong double-sided tape on the flat part in the middle of it, until I can get some screws of the correct width and an appropriate length.The screw holes in the device itself are more like curved slots, with a wider hole at one end, and I thought I'd seen another review say that this is how it attaches to the backbox, i.e. you put the screws into the backbox first then push the holes in the slots over them and twist the unit into place. So this was another source of confusion as neither the screws that came with the device or the ones with the included backbox would actually fit through the holes. But it turns out that's not how it's meant to be installed at all - the front of the device actually unclips by putting a flathead screwdriver in a slot at the bottom and twisting it, then you just screw directly through the curved slots from the front. With the backbox that I used, there was another slight issue in that the part of the device that's left when you unclip the front pretty much exactly fit *within* the backbox, which isn't what you want (because it needs to be in front of the backbox for the actual front plate of the device to be able to clip on). So it took some careful adjustment to get it just right, with the top of the device slightly overlapping the outside of the backbox and the sides/bottom of it falling inside but held by the little tab at the bottom, then screwed in just the right amount for the front plate to clip on securely and also be flush with the backbox.The actual connection terminals on the back of the unit are big enough for 2.5mm stranded cable, but not with much room to spare - the wires in the existing cable to the immersion heater had their ends twisted and folded over in the existing switch terminals, so I had to unfold them and cut the excess off before they would fit in here. I was originally intending to replace the existing switch with this device (which would have meant replacing the existing backbox with a larger one anyway), but then I found out that immersion heaters are supposed to have a double-pole isolation switch (which this device apparently isn't, it only switches the live connection on and off rather than both live and neutral), so I decided to install it after the existing switch with a short length of 2.5mm flex cable between them. A 43mm backbox does seem to be about the right size, as it allows just enough room for the wires to run up behind the device and around into the terminals, at least with stranded wires (I guess solid core ones might be more of an issue)After all that, setting up the app was actually surprisingly straightforward. It seems like there are a couple of different apps that can be used to set up and control the device, but for now at least, I just went with Tuya from the Google Play Store. After installing the app, it probably took less than 2 minutes to add the device and create a schedule for it. Yeah, I'd also prefer a 24-hour clock rather than the 12-hour one with AM/PM that the app uses, but it really wasn't an issue at all. It was actually much quicker and less confusing than trying to set a hot water schedule in the Hive app!Also something that isn't entirely clear from the product details here - the icon on the front of the device itself is a touch-sensitive (capacitive) button that switches it on and off manually. And it lights up in blue when power to the heater is on, no light when it's off. When turning it on and off from the app, the device responds *instantly* - it switches on or off in much less than a second from pressing the button in the app. I'm going to avoid setting the "inching" function though, as I don't want it to turn off before the off times I've scheduled.

Firstly they must have listened to previous reviews , because this came with a more than generous 43mm back box and screws to match ! ExcellentWe have a house which is totally electric , so our only hot water source is the immersion heater. I currently have a timer switch which does work , but is in the depths of the airing cupboard and hard to see and adjust. So I removed that and then screwed on the back box and wired up this switch , very easy to do and with the deeper back box , all the screws supplied fitted fine. ( just needed screws to screw back box to the wall) . I didnt particularly read the instructions as I already use the Smart Home app for other sockets , lights in my house , I just opened that and asked it to search for new devices , it found it immediately and deemed it as a 1 gang switch .A quick test of the on and off on the app and the switch responded , great !So i then went into the app and very quickly set a schedule up to turn it on over night for a couple of hours each nigh , so simple .I then got my Alexa to find it , and named it immersion heater , so now when I say Alexa turn on immersion heater it does ! Perfect !really impressed with this as it was so easy to fit and set up , looks really good too in the cupboard with a simple glass front to it .Now I can turn my immersion off and on anywhere in the world !! and change the timer when I want

Bought this switch recently and it is providing the flexibility I hoped for in controlling my water heater.They should provide a deeper (50mm) back box to simplify installation, I managed to use the 25mm back box but it was an effort, the screws they provided did not fit so I had to find the correct ones.