Am I worrying about nothing?

[wordyone]

I have an immersion heater for hot water and it is on a Horstmann programmable timer. The timer and immersion heater have been in place since before I moved here 16 years ago.
I noticed at the weekend that when I switched it on Boost for a short time, when I went to switch Boost off the timer unit was quite warm. And when I felt it again this morning about half an hour after it had switched off from overnight it was still a little warm.
Is this normal? Has it always done that and it is just that I have never noticed before? Or is something wrong with it?
And while I am asking a question here is another - how can you tell when an immersion heater is worn out and needs replacing other than when it stops heating water altogether? Or is that the only way you can tell?
Thanks for any advice anyone can offer.

[HowardKennitby]

What exactly do you mean by quite warm?
I have no idea how long these things are expected to last but if it is getting warm it suggests that the contacts are becoming corroded or dirty.

[deggers316]

your message is confusing ??

[firewatch]

0oooo this is happening with us as well, not sure of our system maker but ors gets warm to.

[askyourgran]

It's a bit confusing, have you had the heater checked out lately, 16 years is quite a long time for the life of an immersion heater. Ask an engineer to have a look at it just to be on the safe side.

[wordyone]

Thank you Howard Kennitby and askyourgran. The most sensible answers.

[The Builder]

I would guess that, if it's switching the heater supply directly, then it might well get a little warm. It's carrying a 12amp load.

Several things can happen to the element over time. Often, they corrode, then water gets into the element and your trip, or circuit breaker will operate.
Otherwise, the element just burns out. Most common by far is that the thermostat fails, and has to be replaced.