hot cold shower

[nick870]

Hi,
Just moved into a new house and the shower (gainsborough 9.5s) runs hot for about 40secs then there is a click (thermostat I guess) followed by cold water . It then runs in cycles of hot/cold indefinitely. Please help. Have looked at several forums and apparently other people have had issues with this shower too.
Thanks

 

[gas4you]

If you live in a hard water area I would think it is the heater can scaled up making the shower overheat and cut out, then it will cool and come back on and so on and so on.

 

[nick870]

Thanks for your help. Is it something you can clean or is will we have to buy a new shower?

 

[hi-spec plumbing heating]

first thing to check with an electric shower going hot/cold is remove the shower head turn to fully hot the flow should be slow.
then turn to cold the flow should be fast is this happening ?

 

[nick870]

Had to go away for a week. Just checked. yes it is slow with the hot fully on and faster with the cold only. Where next?

 

[hi-spec plumbing heating]

is your shower the one with the big black box inside ?