mira sprint shower issue


Postby mozbud » Fri Feb 06, 2009 10:32 pm

Hi All

got a mira sprint, about 18 months old - working fine until couple of days ago then water stopped mid flow and low flow light came on - will work now and again but water stops after a couple of mins and low flow light comes on - most of the time as soon as you press the power button the low flow light comes on streight away and no water comes out at all - have tried turning the temp control to cold in which case still no water but low flow light doesnt come on (presumably because element isnt switched on)

Anyone any idea what the problem is.

Thanks in advance for any help
:D
mozbud
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Postby plumbbob » Sat Feb 07, 2009 12:35 pm

There are two possibilities. Firstly, has the mains pressure fallen? Burst underground pipes can reduce pressure without being obvious except the shower stops working. Try the thumb under the cold tap routine to ensure good pressure.

Failing this, the most obvious cause is a blocked inlet strainer. On older models of Triton it is in the pipe under the compression coupling where the supply enters the unit and is only accessible with the whole unit removed from the wall. On newer (less than 12 months) models, access to the filter is gained by removing the large white nut next to the water inlet.
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Postby mozbud » Sat Feb 07, 2009 9:11 pm

Thanks for your reply plumbbob

I don't think that the water pressure has dropped and my own feeling is that the low flow light is a symptom of the the water outlet not allowing water out not visa versa (ie low flow causing the water outlet not to open)

the other thing that leads me to believe this is that in all the time that we have had the shower it has never once stopped with the low flow light coming on and when it did start working again yesterday I left the shower running, flushed the toilet and turned the bathroom cold water tap on to try to get it to cut out again but it didnt - left it for couple of mins but OK - shortly after turning the tap off it cut out again and couldnt get it to come on at all

the problem is that I dont know how this shower works

If the flow is low does it just turn the element off or the water?

can it sense that the water pressure is low before it allows any water through it because most of the time when you press the power button no water comes out but the low flow light comes on?

if its not low flow that is causing the issue (I dont think it is) then what is - what would cause the power to be turned on when you press the power button but no water allowed to come out or intermittantly for it to come on and run for 2 or 3 mins then the water shut off but power still on?
mozbud
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Joined: Fri Feb 06, 2009 10:14 pm


Postby plumbbob » Sun Feb 08, 2009 9:15 am

Don't forget, the low flow warning light is not actually operated by low flow but rather by low pressure, although the two are obviously connected.

When the shower is turned on, on the inlet side, above the solenoid valve, a plastic rod is forced out by the water against spring pressure and operates two micro switches. If the pressure is insufficient to push against the spring and trigger the switches, the warning light illuminates and the elements switch off. Water continues to flow.

If the flow was restricted on the outlet side, the pressure would build up in the unit and operate the safety relief valve. The low pressure light would not be triggered.

The most likely cause is still low pressure caused by restricted flow. Have you checked the filter yet? It is simple to do (I was mixing Mira with Triton). With both water and power off at the consumer unit remove the cover and unscrew the large plastic nut next to the water inlet. The strainer can be examined easily.
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Postby mozbud » Sun Feb 08, 2009 10:33 pm

Yes I checked the filter, there isnt one, I fitted the shower and thought I had fitted the filter - there was definatly one on when I removed the old shower which I also fitted)

I don't quite follow - if low flow/low pressure turns off the element but not the water then can't see how this would be a low pressure issue as there is either no water at all when you press the power button but all lights are on, or more commonly, now, it works for 2 or 3 mins then the lights stay on but the water just shuts off (actually today it seems to have been working fine - we have all used the shower and not cut off once)

if low pressure just turns off the element looks to me like it must be a fault with the power button or water inlet valve - do you now if either is prone to fault or if somthing would cause either to malfunction

Thanks again for your help Plumbbob
mozbud
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Joined: Fri Feb 06, 2009 10:14 pm


Postby mozbud » Tue Feb 10, 2009 4:14 pm

been OK for a couple of day but wouldnt come on again today

[b]OK - 99% sure its nothing to do with water pressure
[/b]
the low flow light is a red herring, it doesnt indicate low flow, it indicates no flow because the water inlet valve isnt opening (I am sure the water inlet valve isnt opening as there is no sould whatsover other than the click of the power button and not even a drip of water)

think the power switch is working because when it is pressed the low flow light is coming on so must be doing somthing (unless I am missing somthing)

So, specifically, what I need to know is what would cause the water inlet valve not to open when the power button is switched on and (the other senario - what would cause the water inlet valve to close on its own without the power button being pressed after a couple of minutes of use

as I have said, dont think its the power button (but not ruled it out completly) could be the water inlet valve I suppose or is there some sort of interface device between the 2 that could have developed a fault

any further help would be greatly appreciated as I am under pressure from the wife to buy another shower and I am sick of buying shower the breakdown when just out of warrenty

Thanks
mozbud
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Joined: Fri Feb 06, 2009 10:14 pm


Postby mozbud » Sat Feb 14, 2009 11:08 am

Issue resolved, it was the flow valve solenoid, replaced it and shower now working again - Thanks again for the help javascript:emoticon(':)')
mozbud
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Joined: Fri Feb 06, 2009 10:14 pm


Postby plumbbob » Sat Feb 14, 2009 7:46 pm

The electrical operation of the shower is very simple.

When the Start button is pressed, this latches in the "on" position and allows power to flow through the solenoid valve and illuminates the low flow neon. As the valve opens and the water flows under pressure, it operates the two micrswitches in the flow control unit. These switches have two purposes. Firstly to power up the two heating elements and secondly to disconnect, and consequently extinguish the low flow neon.

If we exclude a water supply problem, if the switch was to fail, the shower would return to the normal "off" position with the low flow light "off". If the solenoid valve has failed, either electrically or mechanically, the water stops flowing, and the low flow light remains illuminated.

Remember, this information because I cannot see the device is little more than a guess, and not a diagnosis. I need also to remind you, that shower units contain lethal currents and as this unit perhaps has an electrical fault, be careful how you proceed.
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Postby mozbud » Fri Sep 10, 2010 4:12 pm

Hi Again

Well the shower has been working fine for 18 months since I replaced the flow valve solenoid, but this morning started playing up again

switch it on an everything seems OK for about 30 seconds then the shower start to flow cold, the lights don't change, low flow doesn't come on and the flow seems fine

tried adjusting the flow with the temperature knob but makes no difference water is stone cold

Any ideas?

Thanks
Chris
mozbud
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Postby thedoctor » Sat Jul 06, 2013 9:17 am

We know this is a very old post but it still atttracts a huge number of visitors so if you want some up-to-date information on showers please click on this link http://www.diydoctor.org.uk/alphasearch/S.htm
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