Mira Sport max - TCO - what does it monitor

[WuTan]

Can someone please tell me what the TCO (Termal Cut Out) monitors. By this I mean does it monitor the water temperature in the tank or does it monitor the temperature of the heating rods? Or something else?

The reason I ask is that I am trying to determine if my overheat problem is due to limescale? i.e. perhaps that water temp is not that high but the heating rods are covered in limescale and as such are getting up to cut out temperature without heating the water enough.

Cheers

 

[seco services]

heat of the water in the can

most tco's are two stage if you look at the label on the top you will see two numbers, say 50 and 80 they are all different.

If the temperature reaches the lower number then it will cut out and reset however if it reaches the higher temperature it will cut out and it will not reset.

 

[WuTan]

Thanks for that.

Can you please tell me why my shower is cutting out when the temperature is not that hot (tepid). Someone suggested it was due to limescale in the tank but I don't see how this can be the case if the TCO monitors the water temperature?

My symptoms as listed in a previous mail are as follows:

I have the Mira Sport Max - I have searched this forum etc but cannot find an exactly similar problem or one with a definitive answer and solution...

Had the shower for 2 years. Over this time I have had to increase the temperature dial from half way to 3/4 of the way to achieve the desired temperature. Recently the unit will cut out - i.e. the overheat light will come on and hence water temperature will go cold (allowing the system to cool back down). Then the overheat light will go off and the water temp will increase again for say a minute or so, and so on. The cut out (overheat) seems to occur at quite low temperatures (water still feels tepid) - i.e. I would not have thought that it should only cut out if the water coming out of the shower was quite hot.

Flow seems to be good (pressure does drop off at the higher temperatures but I think it is acceptable). I have checked various items with the multimeter (although far from an expert) i.e. Heating rods seem to have the right resistance. Continuity across the Thermal Cut Out Switch (TCO) until it trips and the overheat light comes on.

Any ideas would be appreciated - Could it be due to limescale in the heating tank? Could it be a faulty TCO that cuts out to early? etc etc

Cheers in advance.