I'm looking to put our immersion heater on a timer. It's protected by a
16 amp fuse so I assume the timer needs to be rated the same. Many of
the timers I've found so far seem to be 13 amp, even though some claim
16 amp in the headline description.
Anyone able to suggest something suitable?
And a thermostat to work with it? The current immersion heater doesn't
On Wednesday, 8 June 2016 20:14:48 UTC+1, F wrote:
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.
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
http://tinyurl.com/hawlk2t mounted in one of these
http://tinyurl.com/jpwz7eg . It also needs an isolating switch, a
pattress and a junction box. The Sangamo is an electronic controller,
wired in, so no plug and socket arrangement, and has 16A capacity
which, like you, I felt was important at the time. It's probably more
sophisticated than I need, as it's used just as an on/off timer at the
same fixed times overnight to take advantage of E7 electricity, but it
works OK and does the job. My only reservation is that the display is
microscopic and difficult to read unless you get close and have it
well lit, e.g. with a torch.
As an alternative to mine, you could try these purpose-designed
immersion timers, also by Sangamo http://tinyurl.com/jydsg3j Might be
simpler to install, easier to read, and has its own case. If I'd been
aware of them, I'd have gone for the PSD version, in the middle.
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.
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.
Is the timer because the tank was boiling when the immersion was left on or
for convenience to save you manually switching the HW on and off?
If you are still happy to use a switch and are just forgetting to turn it
off then you might be better using something like
What timer did you buy?
I have fitted so few that I cannot give a recommendation. The ones I have
fitted have been awkward to fit but seemed to have worked well.
Now what is the difference between these two
I haven't found one yet so have been using one of my existing electronic
switches (bearing in mind earlier warnings about the plug/socket contacts).
The second , more expensive, one is a 'General Purpose Timeswitch
c/w Voltage Free Contacts' and 'Switches up to 750W incandescent or
halogen lighting/750W fluorescent lighting/100W compact fluorescent
lighting (cfl’s). Not suitable for discharge lighting'. There is no
mention of this with the other which is described as an 'Immersion
Heater Timeswitch' rather than a 'General Purpose Timeswitch
c/w Voltage Free Contacts'.
Does it matter?
Both models have L-in and N-in terminals, additionally
the T03 model has N-out and SL-out
the T04 model has S-in and S-out
so for the T03 they probably cut one link and adding two others in the
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