Immersion heater timer

Domestic immersion heaters are 3 kW maximum so a good quality 13 amp timer will be adequate.

The immersion heater must have a thermostat and all new ones should have a secondary safety cutout with a manual reset. The thermostat will be inside the cover of the immersion and usually slides into a pocket so it can be re placed without draining down the cylinder.

Owain

Thanks.

The immersion heater in question is at least 38 years old and will boil the tank if it's left on!

The immersion heater in my late mother's hot water tank has a thermostat, and it dates from 1960. It may just be that your thermostat was never set properly, or the setting has drifted over the years.

I'll investigate once I've plucked up enough courage to disturb the huge amount of 'stuff' in the cupboard!

Meanwhile, anyone got a recommendation for a digital timer? Or do I use a spare I have that is rated 13 amps and which I use for switching lighting when we're away?

I would need to replace the present immersion heater switch with a 13 amp socket and put a plug on the heater lead to plug it into the timer. Any problems there?

I went down the same road as you're going down, some years ago. My existing timer was just a plug-in jobbie that plugged into a socket in the airing cupboard, and the immersion heater plug plugged into that. But I was worried about the current capacity of the timer, and when it eventually packed up, I installed one of these

As an alternative to mine, you could try these purpose-designed immersion timers, also by Sangamo

Are you sure about that?

Power off and lift the metal cap covering the immersion connections to the tank.

Have a look and I am sure you will find a non working stat dial under the cover.

Thanks, the PSD would do the job for me but it's quite expensive compared with the plug-in type! But, of course, you get what you pay for...

If you do go down the 13A plug and socket route (and I wouldn't recommend it) make sure you use a good quality one.

I tried doing this for a friend (long story) but had failures on plugs and sockets and ended up putting in these

These were on a 20A radial circuit, not a ring main.

I think you should use a "wired in" timer. No doubt Adam or someone else who knows the regs will comment shortly.

Also make sure you use suitable heat resistant flex to the heater.

A job for tomorrow!

Use a mechanical timer. IME digital timers are a pain.

There is probably nothing more than a nut on a threaded bar holding down the metal cover.

When you open it you will see (if it is that old) why I said power down before removing the cover.

All the best.

Google for 'immersion heat timer' there are lots of products these days. I had to replace my Smiths timer with a similar (identical) product from another supplier.

I would make sure you don't already have a thermostat. There are many products for central heating systems, but they would not be able to handle the current without using a relay.

A potential problem with plug-in types for immersion heaters is poor pin/socket contact resulting in the pins getting hot and risking a fire, due to the high current involved. With what is in effect two plugs piggybacked, you double the chance of that happening.

That is true of ours. Of course one issue after a few years was that the internal battery which was soldered in, eventually dies and the next power cut mangles the settings. Hopefully this issue has now been fixed. I have economy 7 so I have it on during the cheap hours as well, and have an over ride switch for emergencies. Brian

It's what I've had for the last couple of years, and works ok so far. With a load of something like 12 or 13 amps it may be better to use one of the older style time-switches with a synchronous motor and a mechanical switch, rather than the new-fangled things full of electronics - I've have several of these fail on much smaller loads and would be doubtful of using them for an immersion heater.

I chose digital for the battery backup.

But before I get to that there's a mountain of 'stuff' to remove. Enough spare laundry for a medium sized hotel. OK, a small hotel!

I seem to remember the presence of a bunch of unprotected terminals from the last time I looked many moons ago.

I have, and there's a lot of junk out there, hence my request for suggestions.

En el artículo , F escribió:

I wouldn't recommend it. It's OK for other 3kW devices like kettles which are used intermittently, but not really a good idea for immersions IMO.

I did wire up the immersion in a previous house with a plug and socket - good quality (MK) ones - but the plug got too warm for my taste and more so when the door to the cupboard was closed. I replaced it with a FSU in the end. That was for a pretty old immersion like yours which does probably pull the full 3kW. A modern one might be "eco" and draw less current.