Replacing old mechanical timer

[d.i.tryer]

My mum has an old Sangamo s610 timer that could do with being replaced as it keeps losing time, resulting in the heating not coming on at the right time. She's reluctant to get someone in to change it as she is planning to get a new boiler next year so would rather wait but if it is easy enough to do myself I would rather replace it just now for her. She has a very old (practically antique!) and basic system; conventional boiler with pumped central heating and gravity hot water, no valves, no cylinder stat and room thermostat in the hall.
The wiring of the timer is;

Red - Line
Blue & Black - N
Brown - Load
Green x2 - Earth

Was thinking of either Hive or the Drayton MiTime (would've preferred MiGenie but not suitable for gravity systems from what I've read) as a replacement.

Any advice on whether or not this would be a simple enough task is much appreciated

 

[flameport]

There really is no point in spending money on either of those, as when a new boiler is installed it will inevitably involve conversion to a fully pumped system with cylinder thermostat or even a combi.
For now, get a cheap 24h timer to replace the existing one, such as http://www.screwfix.com/p/lap-mechanical-24-hour-immersion-timer-240v/91462

 

[d.i.tryer]

Thanks for the reply. My plan was that whatever I buy would be compatible with whatever new boiler she gets, it won't be a combi as she doesn't want one for some reason. Am I right in thinking that the timer you've suggested is only for the immersion heater? What is needing replaced is the timer that controls the heating and hot water from the boiler (the immersion is rarely used). Maybe I didn't use the correct name for what I was talking about, my mums always called it the timer so that name has stuck

 

[flameport]

The timer suggested is just a basic on/off 24h timer and does exactly the same thing as the Sangamo. Although described for an immersion heater is can be used for many other purposes. It's basically an on/off switch with a clock attached.

Until you know what boiler and system you are getting as the replacement, it makes no sense to guess what might be compatible or suitable for use with it.

 

[JohnD]

Is she a person of an age who finds it difficult to learn complex electronic gadgets?

You can still get mechanical programmers with the rotating wheel method, which are very intuitive. I got my old mum a Drayton SM2, which is simple and pretty good.
http://www.draytoncontrols.co.uk/product/sm2