Misbehaving electric shower-worth repairing?

Have one of these in the spare shower room (installed 5 years ago, so perhaps our's an older model, but look identical as far as I can tell).
Rarely used, but recently started to misbehave. It has 3 water pressure button (low/medium/high), and then a dial to set the temperature. We have always had it used on the High setting, and the temperature dial at around the middle setting.
Now in the High setting the water temperature is far too hot (even with the dial set to minimum). In the Medium setting the temperature is too low (even with the dial set to maximum)...
I assume something to do with a thermostat? Is it worth preparing? Considering its working environment my top priority is safety of course...
TIA>
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
You could check the filter. There's sometimes a little mesh filter, probably on the inlet.
A common problem is scaling. If you think of how scaled up your 2 or 3 kW kettle gets in a year, then consider the shower is probably 8 or 9 kW with the element in a space about the size of a cigarette packet.
I had electric showers in a hard water area and they started to behave oddly including symptoms similar to yours. It wasn't a faulty thermostat, the thermostat was behaving correctly but acting to prevent overheating in a scaled up element.
I couldn't find a way of descaling or replacing the heater element. I replaced the entire unit, then that scaled up a couple of years later (it was heavily used). I got a third one and installed a water softener which seemed to do the trick - it lasted till I sold the house.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 25/10/2012 13:28, metric snipped-for-privacy@yahoo.com wrote:

kettle gets in a year, then consider the shower is probably 8 or 9 kW with the element in a space about the size of a cigarette packet.

including symptoms similar to yours. It wasn't a faulty thermostat, the thermostat was behaving correctly but acting to prevent overheating in a scaled up element.

the entire unit, then that scaled up a couple of years later (it was heavily used). I got a third one and installed a water softener which seemed to do the trick - it lasted till I sold the house.

Haven't thought of that - worth a check.
I am doubtful though as the water here is so soft that out last kettle lasted 12 years and internally still looked the way it did when new...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 25/10/2012 12:27, JoeJoe wrote:

Oops! forgot to include the link to the shower: http://www.qssupplies.co.uk/bathroom-furniture-shower-taps/16251.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 25/10/2012 16:48, JoeJoe wrote:

I have just had to clean the filter on ours to cure exactly the same symptoms - once cleaned the problem was solved. Ours looks slightly different but is a Mira Sport - 9KW I think.
Two screws on top, one on the bottom. Ease off the cover and then the cover on the left side. Carefully undo the plastic hex filter. I found an orange tube which I put under the tap to discover the orange colour washed off to leave a fine clear plastic mesh. I don't know what the orange was but it was obviously impeding the flow.
--
Pete
Lose (rhymes with fuse) is a verb, the opposite of find. Loose (rhymes
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

They don't have a thermostat, temperature is controlled by the number of elements turned on[1] and the water flow (set by the flow restrictor - temp control knob).
If it's over temp at maximum flow then there is either low pressure or a flow restriction so look for anything that would reduce flow, like a blocked input filter. You say you have soft water so it shouldn't be either limescale internally or on the shower head[2]. Try removing the shower head to see if water flow improves. Have you noticed a reduction in flow?
Also, I assume no-one has had the front off? The knob for the temp/flow control usually disengages when the front panel is removed and failing to re-assemble it in the same position could result in less than normal flow at the max posn.
From your link to the actual shower, it's not cheap crap so well worth persevering with.
[1] There are 2 elements of roughly equal power, high is normally both on, medium is one on and low is neither on. [2] shower head blockage would be v bad as it will pop the over pressure safety device in the heater
--
fred
it's a ba-na-na . . . .
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thursday, October 25, 2012 6:00:44 PM UTC+1, fred wrote:

Either not enough flow or too much power. The latter can be caused by a split element
NT
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 25/10/2012 18:01, fred wrote:

No change in flow as far as I can tell... However, I just tried the tip about removing the shower head (no effect BTW), and the "Low Flow" indicator came on briefly when setting was on High with lowest temp. Never seen that light coming on before. Is that a further clue as to the cause?

No one touched it - I am sure of that. I fitted a fair few of those several years ago, so am very familiar them.

That's also what I thought. It is just that the idea of messing about with something electrical that is all but under water, and with you standing in a puddle next to it, makes me very uncomfortable.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Clogged input filter sounds most likely.

I can understand your caution and it is understandable, a shower is a scary appliance, high current, exposed terminals and water to boot but a properly installed one will have a double pole isolator before it which you can and should use to make it safe before opening the case. You can also switch it off at your consumer unit for that extra feeling of safety.
Download the installers manual for extra confidence on the correct way to open and dismantle it. It should show you where the filter is located.
--
fred
it's a ba-na-na . . . .
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 25/10/2012 20:59, fred wrote:

Cheers for that. Found the manual and will give the filter cleaning a go at the weekend.
Thanks to all for now.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 25/10/2012 21:11, JoeJoe wrote:

Just a quick update (too me a while to find the time to follow the advice).
Cleaned the filter as advised, and all is working fine again!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.