The cheap electromechanical timers can be quite poor quality, that
includes ones from Asda Tesco etc.
They can stick on or more often off.
More an issue with frost heating where walking in to 2oC floor
temperature and vulnerable pipework.
Contacts are indeed small & flimsy.
Bigger & far better quality contacts on a car window regulator switch
They run warm on high loads.
A 2kW load for 15mins generates quite noticeable heating. A washer is
only going to run its 3kW heater for a very short time even on a 95oC
China generics supply a competent production sample and utter trash
for production run. The money to be made is simply astronomically, but
so is the money to be lost if you are not the cheapest and china is
NOT a low cost area anymore compared to many other Asian makers.
So... how about an LCD timer, that avoids the crude mechanical
contacts (£2 plug-in timers are not Sangamo quality!) and might just
get you a 16A rated relay. It will be rated less for inductive, but I
think the only inductive load at startup is going to be the solenoid
valves "juddering" if yours does that.
I would add, there are little flood alert alarms available for about
£4.99-9.99 - so you may want to add one of those... just in case.
Economy 7 does not save much on a wash unless 60-95oC, it is drying
where it saves a fair chunk over a year.