Smiths industries Immersion timer ETU2000 failing

[Andrew]

I fitted this about 20 years ago and it has never failed (even after powercuts) until now. Being 'made in the UK' I expect it used better components than all their latest timers. The 7-day plug in timer that I bought in 2010 (also Smiths) was 'made in China' and unless it is plugged into an old BT exchange surge protector, it loses its settings randomly after anywhere from 12 to 36 hours. The ETU2000 is also electronic but it has been bullet-proof until very recently.

Symptoms are that after turning ON, it never turns OFF after the set time. Sometimes it garbles the LCD screen.

The hot tank is very well insulated and the stat on the immersion kicks in at 60C but I don't want to trust this and nor do I want in on 24/7.

This seems to be a suitable time to upgrade to something that I can control via my PC or phone but I cannot find any immersion controllers that are intended for just one heater. Horstmann seem to do one for economy 7 but it is £95. It does have a blutooth interface as standard but the output relays are only rated at 13 amps. All the dedicated standalone single heater immersion timers seem to be rated at 16amps. Is this an issue ?.

If I could find a suitable mains/mains relay with output

16amp resistive switching then I could presumably activate it using a smart plug but there would be some ?back emf to the smart plug at the end of the timing period.

I assume that the main timing logic of the ETU2000 is not at fault. Pressing the Boost and reset buttons for the required 3 seconds resets it, the relay clicks and the output LED goes off (as it should after a timed period). Presumably some discrete component has failed or is failing but I don't have any way of proving this.

There must be relay devices that are intended for use with Zigbee/IFTTT setups that I could use in place of a dedicated immersion timer ?.

Andrew

[Tim+]

I’ve been using a cheap Sonoff Wi-Fi switch to control my immersion heater for years with no problems. My one has been superseded by this one with a slightly higher power rating (20A vs 16A).

SONOFF POW Elite 20A Smart Power Meter Switch, WiFi Wireless Outlet with Power and Energy Monitoring, Control Lights and Appliances from Phone, Manage Energy for DIY Smart Home,Works with Alexa

Other stockists are available.

Tim

[Andrew]

Thanks.

I have been wading through the Vesternet site and all their huge array of offerings. I'll have a look at Sonoff stuff.

I just tried using the 1hr boost button on my ETU2000 and it powered on the immersion and exactly 1 hour later it clicked the relay off, so some of the functionality is still there.

I have a nagging suspicion that it might be external electronic noise making the timer unit go funny, but there is no way of proving this without expensive monitoring kit.

It is 20 years old so it must have a nicad battery. I'll try and have a look inside to see if anything has leaked and damaged the circuit board.

The LCD is becoming difficult to read, their later models seem better in that respect but TBH using an app on my phone is quite appealing.

Andrew

[Andrew]

The amazon UK page seems to show it attached to a din rail even though the Sonoff site shows it fixed to a wall with a cover to protect the mains connectors.

Is yours fitted to a DIN rail or to wall directly ?

Also there is a more expensive version on this amazon page that is physically different and lacks an LCD, and it costs ~£42 rather than ~£24.

I don't use Alexa, so I hope I can just manage it using the phone app to simply set on/off times. I don't care about measuring power usage, I can do the maths in my head.

Andrew

[Tim+]

Just screwed to the wall. Still available but the new one has a higher current rating and is cheaper.

Works fine with the phone app. Easy to program. No need to use Alexa etc. unless you want to.

Tim

[Brian Gaff]

This sounds like capacitor trouble in its psu. they dry out and the unit tends to get low voltages marred by interference from parts of the circuit. My Immersion heater timer lost its battery back up but a new solder in one brought it back to life, and it can now cope with a power cut. I used to have an el cheapo vcr once that had this fault you describe, and it was also very prone to picking up interference from an electronic tube torch. It was a Philips and it never was fixed. Moving it to another part of the room seemed to fix its tendency to corrupt. Brian

[Andrew]

Brian,

Today I have removed it and it is running from a flying lead on my desk and so far it is behaving perfectly !. Grrr.

I am only using a plug and flex from a table lamp, so no earth connection though.

The immersion is still connected to a 15 amp rewireable fuse in the wylex fuse board, so I have no idea if the immersion heater element is starting to fail. How would I test it ?. The original (? dual pole) switch is still in situ, with the original flex feeding the Smiths timer and a new length of heatproof flex going to the immersion. I have connected the ends of the two flexes that went into/out of the timer using a 45 amp output cover so that I can use the immersion manually. I notice that the original switch gets a bit warm after 15 minutes. Not what I would expect. Do switch contacts need to be exercised to remove corrosion ?. For 20 years it has just been left in the ON position.

I still need to upgrade the Smiths timer because it has on old fashioned lcd display that has no backlight and can only be read with a strong light and at a particular angle. There are better modern equivalents that use backlit displays (but I bet they wont last 20 years) and the ability to use a phone, tablet app or some form of home automation is quite appealing

Andrew

[alan_m]

Quite often the backlight only comes on for a short period when you select a function.

[Andrew]

I thought that was pretty well standard behaviour, it's the only time a backlight would be needed.

Meanwhile the Smiths Timer is sitting happily on my desk without any output load, connected with a length of lighting flex to a

3pin plug (and without an earth connection) and it is working fine.

QED the problem must be elsewhere.

[Sam Plusnet]

In your safety protocols for a start. 😃

[Andrew]

Why ?. It has a plastic enclosure, there is no output connection so all it needs is 230V with minimum current draw to test the functionality of the timer. The plastic cover over the in/out mains connections is in place.

I wouldn't mind betting that the earth terminals are simply there to pass the immersion earth through to the house earth and not actually connected to the electronics inside the timer.