Shower flow problem

[KennyHMFC]

After turning back on the stopcock (water had been turned off for about 8 hours) my mixer shower will run for a short while and then the water runs out. I have a combi boiler and have plenty of hot/cold water for running a bath etc, so why does the shower run out? Nothing has changed at all with the plumbing.

[BillyNoMates]

What type of shower is it ? If it's electric is it possibly fed from a header tank which has not filled up again - stuck ballcock ?

[KennyHMFC]

thanks for replying so quickly. It is an electric MIRA shower and I have checked the water tank and it's fine. I have even left the shower off for 36 hours before trying to turn it on incase it was what you suggested.I have also had it running on cold for a short time incase there was and air lock in the pipes but it still cuts out after a while.

[BillyNoMates]

My only other thought is perhaps some debris has been dislodged and is clogging the filters in the shower or even the shower head.

This might be reducing the flow sufficiently to cause the overheat thermostat to trip and turn the shower off. Most electric showers that I've seen have filters which can be removed and cleaned.

[BillyNoMates]

Just re-read your reply and seen that you have run it OK on cold so you can probably ignore my previous reply.

[Robert G]

I'm slightly confused. I, too, have a combi boiler as well as a Mira electric power shower. The only reason I have the combi boiler is because there was nowhere (high enough above the bathroom) for any water tanks. But if you do have a tank, I don't think you have to have a combi boiler rather than a traditional one.

Anyway, I just wanted to say that I have had similar problems to yours in the past. In my case, opening the stopcock to just the right amount is fairly critical because, on the one hand, the incoming water pressure for the boiler mustn't be more than a certain amount, and on the other, the cold water pressure to the Mira must be more than another certain amount, otherwise these units don't function correctly. And in the case of the shower, I think that it will shut off the water flow if the pressure is too low.

Your Mira unit should be supplied with cold water from the
main, and not indirectly from any tank. Your bath, etc, should be supplied from the tank, and it sounds as though your boiler is, too.

So, to get to the point (at last!), I suggest you see if you can open the stopcock a little further. If you have definitely done that already, then the other thing I would suggest, assuming you live in a hard water area, would be to descale the shower head.

Good luck.