Mira Sport shower problem

[junep]

Just moved to a house with a Mira Sport electric shower installed. It's on the 2nd floor and dribbles instead of providing a meaningful shower. Looking at pictures on the web, I think the shower is a 7.5kw model and I think the water feeds direct from the mains because there is no tank.

Can anyone tell me if a higher kw model would work better or does it depend on the water pressure?

Also if a tap is being run somewhere else in the house, the shower pressure changes - I thought this isn't meant to happen with electric showers?

 

[stem]

Electric showers like yours usually have two elements, for example 3kW & 4.5kW on the high setting both will be on to give 7.5kW. That is the maximum heat the unit generates. The flow of water is then adjusted to give the temperature you require. More flow=cooler water, and less flow=warmer water.

In cold weather when in incoming mains water is colder, the flow has to be reduced further in order to get a final reasonable temperature.

When water is run off elsewhere in the house the pressure drops and changes the flow through the shower, and so the temperature changes. Some electric showers claim to be 'stabilised' but in practice they seem only able to cope with small fluctuations.

A higher rated shower will be able to heat more water. 7.5kW is very low these days, 10kW is not uncommon and gives much better performance. However, you will probably have to upgrade your existing cable to your shower as the existing one is probably too small for a 10kW load.