Mira Sport Shower Not Heating Properly

[bob.smithson]

While using the shower today, the main switch of our consumer unit tripped. It has an RCD and none of the individual circuit MCBs tripped.

When I switched it back on and restarted the shower, everything seemed OK, except that the shower is not heating properly now. It does heat a bit, but it is as though it is on a lower setting than it actually is.

The shower is a Mira Sport (9.5 KW I think) and is about 7 years old. It's in good nick cosmetically at least and I'd like to keep it if possible.

Any ideas what the most likely problem is and anything I can test to confirm? Are parts easy to come by?

Thanks in advance for help.

-- Bob

[Stephen Dawson]

Sounds like the heating element is up the creak. Spares are easy to find on the net. Element is about £60 + vat and delivery

[fred]

In article , Stephen Dawson writes

Just to add, the reason that it has dropped in power and not failed completely is that these things invariably use 2 separate elements, one of which appears to have failed. Each element should be in the range

10-12ohms so they're easy to check. As this one appears to have failed with leakage to earth I'd be inclined to isolate it straight away.

Except for the electronically controlled ones these are very simple to work on but be aware that you are combining a high amperage power supply, water and naked bodies so best to treat them with respect.

[Matt]

If it's like this:

Then you might have encountered a very common problem with older Mira showers.

If it's the later design like this then all bets are off

Isolate the electricity and remove the front cover, put the shower head/hose well out of the way to avoid any splashback.

Replace the knobs and turn the shower on to get water flow, as there is no electricity feed there will be no heating.

Look for a leak/dribble running down the wiring. Chances are pretty high that the pilot valve seal has leaked, the usual result being that one of the micro-switches destroys itself. The complete valve assembly (part number 419.87) including the micro switches is about 30 quid. You'll need a torx screwdriver to change the valve.

[bob.smithson]

Yes, it's this one, unfortunately:

So you don't think it is reasonable to assume it is probably the heating element like the others suggested? How about the fact that it still partially heats? fred suggested that that was a symptom of one of the parts of the two part element failing.

I'm in a bit of a quandary: I'd pay =A360 for the element to fix it, but it's a lot to risk if that isn't the problem, so I need to find a way to diagnose the problem. If I get someone out to look at it, and it is the heating element, it is not going to be cost effective by the time call-out/labour charge is added. I may as well buy a new shower.

Thanks

Bob

[bob.smithson]

Thanks for the advice. Could you give some more details on how I go about checking the element. | have a cheap multimeter thing but I'm not much of an expert on using it. (Mainly just used it for continuity testing.)

Which are the electronically controlled ones? Mine is this one as in the link Matt sent:

Thanks

Bob

[Vernon]

If you look either in the handbook or on the Mira website you can get the wiring diagram for the shower

In the illustrated parts diagram posted previously, the heater is item

416.34/35. There are two elements to the heater as shown on the wiring diagram as "load". If you use your meter and measure the resistance (ohms) accross the load, you will probably find one is high, and the other low. Please remember to isolate power to the shower before you take any covers off etc.

About three weeks ago, our shower, did exactly the same, tripped the MCB. After resetting the MCB the shower was only producing warm water when set to high, if set to med it produced cold water. But the heating element is typically £60+VAT, so you have to work out if is it really worth paying for a repair vs buying a new cheapo shower.

Vernon