My 1998 Mira Sport 9.0kW shower tripped the RCD yesterday and today was running cool, and clearly not right so I switched it off.
The symptoms sound the same as on a 10.7kW Mira Sport issue reported by Alan on another recent question, which turned out to be the heater tank. I've knocked the power off and taken a peek inside and the heater tank does look suspect as I can see corrosion around the base of all four copper tubes leading to the heater elements. Everything else looks fine, but is there anything else that I should consider? Can replacement of the heater tank be done with the shower unit in-situ, and does the water need to be off (nb. I'll probably turn it off anyway). Many Thanks.

Dave, March 2007

I have a Mira sport 9.0kW, It was working fine till last nite. This morning I was brushing my teeth, open the bathroom sink tap and when I closed it again the shower starting pouring cold water from the bottom (outlet to the hose/shower head)!! The shower was not even ON.... freaky!!! I was told that I need a new heater tank, that the heater tank is gone! Is that true or is there any other reason?? I want to buy the tank but not sure if that is the real problem! Any help??? Thanks

Manu, March 2012

Many thanks - I went for it and swapped the heater tank this morning. The heating elements on the new heater were both about 12 ohms, and I was able to confirm that one of original one's elements had indeed blown. I reckon when it blew the element must have briefly contacted the heater tube and tripped the RCD.
The swap can be done with the shower in situ (with power off!) - the only fiddly bit is a clip on the tank that locks underneath a corresponding clip on the rest of the mechanism but it can be done with some careful 'easing'.
The new heater tank was a slightly different design to the original but all instructions were included.
All working now for about £65 and about 20 minutes effort.

Dave, April 2007

you can replace the heating element. there is two elements in the copper cylinder, so there will be four rods coming out the top two for each element.do a continuity test to see what two go together. once you have found the two that go together you can check resistance on them you should have 10-20ohms. but make shaw a electric is off. sometimes its just cheaper to fit new shower.

hi-spec plumbing, March 2007