Moonshine Posted October 16, 2020 Share Posted October 16, 2020 I have a mira sport max 10.8 kw with air boost which has been working fine and just recently even on its highest setting its just luke warm. About 6 months ago i replaced the thermal cut out switch as this was faulty, and it worked fine, now its on the blink again. I have looked at the mira showers website which indicates that i need a new PCB or heater tank. So far i have the following observations / fix attempts; Shower is cold on eco setting, luke warm on highest setting. When shower first turns on in the first 10-15 seconds it gets hot, then goes to luke warm When the shower is running and a toilet flushed the shower gets very hot (seems the heater tank is working) then back to luke warm once the toilet cistern is filled. Brought a new thermal cut out switch and replaced - no change Brought a new PCB and replaced - no change Checked the heater tank elements, both showing ~10 ohms and continuity I am not at a loss as to what else to try other than getting a new shower, anyone have any ideas? Link to comment Share on other sites More sharing options...
ProDave Posted October 16, 2020 Share Posted October 16, 2020 Do you have a multimeter to take some electrical measurements? Does the water flow rate vary as you adjust the temperature knob? Link to comment Share on other sites More sharing options...
Moonshine Posted October 16, 2020 Author Share Posted October 16, 2020 2 minutes ago, ProDave said: Do you have a multimeter to take some electrical measurements? Does the water flow rate vary as you adjust the temperature knob? yes i do, no fluctuation in flow rate with adjustment. Link to comment Share on other sites More sharing options...
ProDave Posted October 16, 2020 Share Posted October 16, 2020 5 minutes ago, Moonshine said: yes i do, no fluctuation in flow rate with adjustment. It's a mechanical problem then. the basis of all electric showers is the heating power remains constant and you adjust the temperatue by adjusting the water flow rate. Running briefly hot then going cold is usually a sign of too little flow, it overheats and shuts off the heater. Some showers have a little toothed belt to connect between the knob and the actual flow control, check that has not snapped. Can you post a picture of the mechanical bits around the temperature knob? 1 1 Link to comment Share on other sites More sharing options...
Moonshine Posted October 16, 2020 Author Share Posted October 16, 2020 3 minutes ago, ProDave said: Some showers have a little toothed belt to connect between the knob and the actual flow control, check that has not snapped. Can you post a picture of the mechanical bits around the temperature knob? Boom, I think you have solved it, just taken a picture of the back of the knob. This white bits I presume the broken teeth! Any idea if you can buy just the control or need the whole front face plate? Link to comment Share on other sites More sharing options...
Gav_P Posted October 16, 2020 Share Posted October 16, 2020 ??? Link to comment Share on other sites More sharing options...
Moonshine Posted October 16, 2020 Author Share Posted October 16, 2020 Check out the rotation of the nob completely, but has missing parts turning the black dial (which changes the flow), broken teeth. 20201016_200336.mp4 Link to comment Share on other sites More sharing options...
ProDave Posted October 16, 2020 Share Posted October 16, 2020 Video won't play (probably my poor broadband) What "teeth" are you referring to? those 4 prongs? Can you post a picture of the part the knob mechanism mates to? What's that slightly trapezoidal hole just down and to the right? Is that where a spindle engages? if so that should turn as you rotate the knob and there is either a gear or belt between them. Link to comment Share on other sites More sharing options...
Moonshine Posted October 16, 2020 Author Share Posted October 16, 2020 10 minutes ago, ProDave said: Video won't play (probably my poor broadband) What "teeth" are you referring to? those 4 prongs? Can you post a picture of the part the knob mechanism mates to? What's that slightly trapezoidal hole just down and to the right? Is that where a spindle engages? if so that should turn as you rotate the knob and there is either a gear or belt between them. At the bottom of the control the are a number of white bits of plastic, which I presume have come from the control mechanism, see the red circle below. When I turn the temp control the trapezoidal hole turns but has gaps in its rotation (stops) even though the temp control is still moving. I think it is this control that hasn't got the full range of movement to turn the shower to it's highest heat Link to comment Share on other sites More sharing options...
ProDave Posted October 16, 2020 Share Posted October 16, 2020 wedge something in the trapezoidal hole and then apply some "load" to it and see if it rotates when driving a load. Can you see anything in the gap between the front and the black "plate" or is it totally enclosed? It does not immediately look like that is meant to dismantle. Link to comment Share on other sites More sharing options...
Moonshine Posted October 16, 2020 Author Share Posted October 16, 2020 1 minute ago, ProDave said: wedge something in the trapezoidal hole and then apply some "load" to it and see if it rotates when driving a load. Can you see anything in the gap between the front and the black "plate" or is it totally enclosed? It does not immediately look like that is meant to dismantle. No it doesn't so it looks like the temp control nob won't turn the spindle to control the flow, so it looks as though it is the control nob that is knackered. I have just turned the flow spindle on the unit 90 degrees, and fitted the front cover, now it has a decent heat to the water. So it was definitely the mechanical control of the the temp that was broken rather than anything internal. From a quick google it looks like you are right and i need to buy a complete face plate, ah well at least the problem is found and a temp solution found. Thank you very much, i had completely over looked the mechanical side of it! Link to comment Share on other sites More sharing options...
SteamyTea Posted October 17, 2020 Share Posted October 17, 2020 (edited) Can you get the part 3D printed, ask @Onoff Edited October 17, 2020 by SteamyTea Link to comment Share on other sites More sharing options...
PeterW Posted October 17, 2020 Share Posted October 17, 2020 This can sometimes mean the flow control valve has failed or is scaled up. They become stiffer and then the control dial pins sheer when it needs too much force to move the flow valve. At this point if you’ve replaced PCB and now need new front cover and potentially the flow valve I would be swapping the whole unit. Link to comment Share on other sites More sharing options...
Onoff Posted October 17, 2020 Share Posted October 17, 2020 32 minutes ago, SteamyTea said: Can you get the part 3D printed, ask @Onoff Be happy to but at the mo have only successfully printed in PLA. I don't know how warm it gets in there but PLA isn't good when it gets warm. That and my lad is back at uni so the printer is sitting idle. I can only measure/draw/model in AutoCAD. Never even worked with a slicing program like Cura. Keep meaning too learn it but... (Don't like electric showers, give me pumped any day ? ). Link to comment Share on other sites More sharing options...
SteamyTea Posted October 17, 2020 Share Posted October 17, 2020 24 minutes ago, Onoff said: give me pumped any day Yes, they work a treat and mine has not needed anything done to it for 12 years at least, may be longer. Link to comment Share on other sites More sharing options...
Onoff Posted October 17, 2020 Share Posted October 17, 2020 2 minutes ago, SteamyTea said: Yes, they work a treat and mine has not needed anything done to it for 12 years at least, may be longer. Mains pressure shower I guess is a good way too, either via TS or UVC but they have their own issues. Link to comment Share on other sites More sharing options...
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