is there an easy way to see if the solenoid valve, micro swicthes, or thermostat in an electric shower is faulty? or if a cheap shower is a direct replacement easier?
Yes, a multimeter will allow you to test everything. However if you've no idea how to use one I'd recommend getting a plumber in.
Some manufacturers are offering a repair service with 12 months guarantee at a fixed price. Sometimes offering customers better advice pays dividend in the end.
I also offer to repair electric showers at a fixed 1hr labour rate plus parts, and guarantee the repair. That wasn't the question The problem arises when the cost of a repair plus a new heater can costs as much as replacing the shower. But then you have to ask what to replace it with, shower footprint, left/right hand entry, whether tiled behind, whether 17th Ed compliant, etc. Hence I believe it's better to: a. diagnose and repair if you have the skills, or b. get a local plumber in who can quickly run down the options and costs rather than spend a lot of money repairing something that's not economically sensible to do
I agree with Mr Ian on this one. The problem I find is that having diagnosed the fault, ordered up the part, returned and fitted it the total cost is generally prohibitive. Yes, it is cheaper for the customer to have you running about and doing mail order, but on a profit basis this sort of work is a non starter for me. Change it for a comparable unit unless you can diagnose and source the parts needed quickly.
Finding the fault usually only takes seconds - heater can, thermal cut out, microswitch or PCB. Then order from showerdoc, add my £20 to the part, re-fit and away you go.