Electric shower overheats

12345679

I have a mira escape 9.8kw shower but it has always over heated because the water flow is only about 4.5 litres a minute. It started tripping out the shower rcb on the consumer unit but I had it checked out by a electrician and he said wiring is ok. After advice from mira to reset temperature it now just constantly overheats and the low pressure light comes on then it goes cold then heats up and repeats
Would getting a shower with 8.7kw heater be more stable in this situation or would it still overheat?
Thanks

Jonesya

Is there nothing you can do to raise the water pressure?

jk0

Just turn down the heat control, surely?

Lorian

what's causing such low flow?

- are you sure its plumbed from the mains and not cold water tank
- No part open / non-full-bore maintenance valves?
- Stopcoc k fully open?

DorsetLad

Buying a lower kW shower unit probably won’t help. There may be a cheap solution (see below), or it might be more expensive!

Firstly, I’m not an electrician, but if the unit is tripping the RCD (if that is what you mean) and the cabling has been checked, it suggests to me that there is an earthing/electrical fault within the shower unit itself. Hopefully an electrical expert on this forum will answer this question. Is the unit old or new?

You say water flow is only about 4.5 litres per minute. With these electrical showers, the flow rate is not fixed but is controlled by you using the rotary dial: the unit supplies heat at a constant rate (9.8 kW), so the faster the flow of water through it, the lower is the output temperature. If you turn the rotary dial to the coldest setting (= highest water flow rate), does the flow increase to a reasonable rate? Is the water then hot or cold?

Below are some other suggestions to try. Note that (judging from the images of this unit on the internet), the warning light on the unit indicates low flow, not low pressure. Low flow could be due to a restriction in the flow of water to the unit, within the unit, or after the unit.

Some possible causes for low flow if your water for the shower unit comes from a cold water tank in the loft:
1. Too little vertical distance between the cold water tank and the shower unit (this would have been apparent when the shower was first installed).
2. Use of a “high-pressure” shower head / handset (probably the type supplied with the unit), when the pressure from the tank is likely to be at lower pressure. If the water is from a cold tank in the loft, you should buy a shower head / handset suitable for a low-pressure water supply. These are readily available and have more/larger holes to allow a greater flow of water at lower pressure.
3. Blockage in the handset itself, e.g. scale. You can test this by unscrewing the handset and seeing if the “overheat” problem goes away.
4. Blockage of the inlet filter within the unit. The unit cover will have to come off to clean the filter – best left to an expert unless you know what you are doing.

Some possible causes if your cold water comes directly from the mains (which should be at high pressure):
1. Causes 3 and 4 above.
2. As suggested by a previous poster, valves or stopcock not fully open, or some other restriction to water flow to the unit.
3. Low pressure in the water mains.

12345679

thanks for your reply. I know it is low mains flow I just hoped maybe a lower Kw would help.
In the summer its ok on setting 2 but in winter its too cold, and on setting 3 in overheats.
When I turn the flow dial "cold" it appears to increase flow but the "low flow" lights comes on and the water goes cold. turning the flow dial clockwise to "hot" it over heats and again the "low flow" lights comes on and in the middle area the low flow goes on and off.
It did trip the consumer unit but resetting the showers as told by Mira service has stopped it.
thanks again for your reply. I think a tank may be the only answer but when people say it needs to be around 50 gallons it puts me off!

DorsetLad

I don't see how a tank would help - this is likely to always give you low water pressure, whereas the mains ought to give you high water pressure. It is also likely to need some replumbing.

As I said, there are some possible causes for low flow that would be relatively simple to test for and fix, e.g. new showerhead for £10-£15 if it is that that is causing the low flow. What is the water flow like out of taps that you know are also at mains pressure, e.g. the cold tap in your kitchen? If that is fine, then the problem lies in the in the pipes to the shower (valves not fully open in the pipework), the flow within the shower unit (blocked inlet filter), or the connections out of the shower (wrong shower head, or maybe a kink within the flexible pipe).

12345679

Thanks again for your reply. The 4 litres a minute was measured from the kitchen tap. The water pressure/flow can not be changed with out a lot of money, which is why I was hoping for a quick fix. Thanks for your suggestions.

Ectophile

According to this OFWAT page https://www.ofwat.gov.uk/publications/water-pressure/ your water flow should be at least 9 litres per minute.


Have you tried contacting your water company to find out why your flow rate is so low?