Problem with Mira M7 electric shower.

Hi

We have one of these showers in our house, and it's at least 13 years old. It's never been the most powerful thing in the world, as it's only really powerful when it's running cold - as soon as you turn the heat up, it's power decreased a bit.
A few days ago, it's power seems to have dropped quite a lot and getting it to run hot means that it's running at almost a dribble. I don't have the manual for it, so don't know where to start. Any ideas?

Thanks.

The flow wil be reduced due to the water being colder and it has to work harder to heat the water. The heat exchanger could be scaled up and it may be prudent to consider changing.

You may want to upgrade to a 10.5 kw shower which will give you a bit more flow but you will probably have to upgrade your wiring.

Thanks. Is there any maintenance I can do on it? How can I tell if the HE is scaled up?

Hi

Took the front off the shower. It all looks a bit white and scaly inside. I'm a bit of a novice - is replacing the shower unit quite straightforward? On the face of it, unscrewing old pipes / wires and wiring it all up again doesn't sound too taxing, but I'm sure it's not as easy as that. To be honest, I can't remember what kind of connection went to the water inlet - if it involves soldering, I'm screwed!
Is it too much to hope that a new shower I buy will fit neatly on to the existing fittings? I think the old M7 is a 7.5 kw shower - what would need to change about my wiring if I got a more powerful one? Would something like this be suitable? http://www.focusdiy.co.uk/invt/990453
Sorry for all the questions.

Cheers

Normally a 15 mm compression fitting.

You may get away with original wiring but I would ask the sparks in the electric forum.

Thanks for that - I'll post a thread over in the sparkie's section.

Can I go back to one of your earlier comments? You mentioned that the heat exchanger may be scaled up and might need replacing. Does that mean that the HE might need replacing or the whole shower unit? If it's just the HE, can this be obtained directly from Mira and fitted myself? And how would I actually know if the HE is the culprit?
I have noticed that for the last month or so, when the shower is on, there a steady drip of water coming out of the bottom of the unit, pretty much underneath where the inlet is. Can't remember if it's always done this, but it doesn't seem right.

Even when the shower is on it's cold setting, it's not nearly as powerful as it used to be. Before, if you turned it on and placed the shower head in the bottom of the bath, it would writhe about and spray water everywhere. Now, it is nowhere near that. Could the whole issue actually be something to do with a drop in mains pressure? Just a thought.

Cheers

Try a new shower head first.

Could well be a drop in mains pressure.

Will do, thanks. What's the simplest way to check the water pressure?