Mira Shower heating problem

[robertmorgan]

I replaced my old shower recently as it had been having problems for a couple of months and finally packed up, I had initially suspected a water pressure change but then it packed up so I assumed it was just past it. I replaced this with a Mira Sprint, it's fed directly off the mains like the previous one. The problem I'm having with it is similar to the one the original shower had before it packed up, in that I can have either hot water with next to no flow, or freezing cold water with a decent flow, which is the same problem which affected the previous shower before it packed up. The instructions on the Mira tell you to commission it by switching it to the lowest power and then working up, however, only on the highest power is there any heat at all, but this reduces the pressure too much. I guess it could be due to the mains water being very cold at this time of year, but I wondered if there is any way of improving the heating capability of the shower, it seems that adusting the control changes not only the amount of heat it puts in but also the flow, so I wondered if it's possible to get the thing to put more heat in at a higher flow rate than it currently does. Any ideas?

[Sadly]

It is even simpler than that - the heat level is kept constant and the temperature is controlled by adjusting the flow. The faster the water flows the less time it has in the heater to warm up and so the colder it comes out. The slower the flow the longer it stays in the heater so the hotter it gets.

If you have either cold or scalding you probably have either high flow or eff-all. I suspect that there is something reacting to the flow and changing the pressure - maybe an air-lock could cause this? What happens if you turn the shower to a mid-possision then get someone to gradually turn up the kitchen cold tap? This should change the flow and also the water temperature.

Another option is that you may be using the wrong shower head - most electric showers come with a head that is matched to the shower, changing this for a nice fast-flaw one (or even an easy to clean head with rubber bits) is likely to cause much grief!

[John Rumm]

Yup, that is about what you get from an electric shower... it will be worst at this time of year with the supply water being particularly cold. Even a 10kW shower will only give you 4L/min of water at a usable temperature this time of year.