On 31/01/2018 08:54, jim wrote:
jim k Wrote in message:

I want to add a boost function to the rather basic immersion
heater switching of my heating system.

Currently there's a simple switch with neon.

What do I need to look for when choosing?

Amy other gotchas?

TIA

New thread refers:-

Wiring immersion boost switches... Gotcha!


I have a Smiths electronic immersion timer. As well
as four on/off times per day it also has a boost
button. Press once for an hour, twice for 2 hours,
etc. Being electronic I presume that it does its
switching at the AC crossing point when no current
flows.

Has been running for 15 years without problems,
but it was made in the UK, not China.

The Smiths plugin 3pin electronic timer that I
use to control my fridge, was Chinese-made and it
loses all its settings randomly, unless it is plugged
into an ex-BT mains filter socket that used to be used
inside a BT exchange for something.

One day I will try and obtain the correct electromechanical
thermostat (*) to replace the one that failed a week after the 2
year warranty expired (in 2010). But at this rate I might just
get a new fridge (in another 10 years time).

(*) Liebherr's UK agent won't supply (elf n safety) but will send
out an engineer for £175 !, which is 2/3rd what I paid for the
entire fridge.