Replace flash immermat with digital timer

10 Mar 2023
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Hi everyone,
I would like some wiring help please!
I want to replace the old analogue timer with a digital one.


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What EPH are you trying to use? Looks like a thermostat which isn’t a timer.
OK analogue is an infinitely variable control, digital is on/off control, I can see how a thermostat can be either, but not really a timer, all timers are digital they turn the heating on/off.

Your diagram shows 6 connections, if we include earth, the power it seems is 230 volt (low voltage) and the relay contacts any voltage you like called volt free so could be extra low voltage.

The last picture shows 6 wires, we can see the earth, and the line and neutral going into the switches fused connection unit (FCU) but the picture of the 4 core cable tells us nothing, we don't even know if this is before or after, low or extra low voltage or a combination of both.

With central heating boilers we have two broad types, those which have the valves and controls built in, and those where the valves and controls are external. Often called Combi and System boilers. We also have two electrical control methods, on/off or digital and variable output or analogue, the latter often has connections to the e-bus, unlikely you have an e-bus control, however it could be 24 volt or 230 volt and it is important we don't mix them.

In the main system boilers are controlled by the motorised valves, and the motorised valves in turn are controlled by timers, thermostats or a combination of the two, where combi boilers often only control is a thermostat direct to the boiler.

Today often the main control is with the return water temperature, we have the ability to turn on/off electrically, but the minute by minute control is with the water and the thermostatic radiator valve (TRV) together with the lock shield valve. My TRV heads are electronic and include time as well as temperature.

But as it stands not a clue what you need.
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Show us the old thing you want to replace.

Is it the radiators you want to control?

Show us the thermostat as well.
The pictures I took are pretty rubbish actually, sorry!
The wires in it are labelled
1L in
2 N in
3 N out
4 L out
So it's an immersion heater timer. Are you using it for an immersion heater?

What's the amperage rating of your new timer?
I think it is 3Amps, which sufficient for a gas boiler, but not for an immersion heater.
I replaced my immersion timer with one of these, does the job, 7 day timer with 4 daily settings.
LAP 7 day immersion timer
I think it is 3Amps, which sufficient for a gas boiler, but not for an immersion heater.
No its for the boiler, just does heating. All the hot water comes from solar on a separate system

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