new shower problem

[skuba]

apologies if this is not the correct section, but i wasn't sure whether this should be in electrics or plumbing. anyway, i've recently fitted a new mira sport 9kw shower and it's got a strange problem. when i turn it on, if the control is set to 'high' and the temperature dial is over half way (where it should be warm/hot), the water runs cold! it doesn't matter how long i leave it running, it never gets hot. but this is the weird thing, if i move the control dial to 'low' and then immediately back to 'high' the water starts to get hot straight away!?! it's almost like moving the control dial from 'high' to 'low' and back to 'high' resets the shower and it starts to heat up. i'm pretty sure this isn't expected behaviour because i've had the same shower before and i never had to do this. front of shower panel shown below (p.s. 'low flow' is not lit up so i know this isn't a water pressure problem)

any ideas?

thanks

 

[HawkEye244]

It sounds defective to me. I would phone the manufacturer first before returning : https://www.mirashowers.co.uk/support/contact-us/

That is the type of thing you would expect to happen after some years of use, not straight away.