Electric shower poor water flow on hot, good on cold

[twonky]

I have a Triton Rapide 3 electric shower that was installed several years ago (by previous occupants). The water pressure from the shower head is really powerful when the shower temperature is set to the coldest setting but very poor when set to a hot (comfortable showering) temperature.

From my little bit of research I see that the heater in this unit works at a constant level and that it adjusts the flow of water through the heater to achieve the desired temperature; the slower it flows, the hotter it gets. So I understand that the water flow is going to be reduced when hot but it seems to be drastically reduced in my case.

Is there any likelihood this shower unit has a fault with its flow control / heating element? Or should I live with it / get a more powerful unit? I think this one is 8.5 or 9.5KW but not 100% sure.

 

[scoobydo123]

As you can probably appreciate this time of year the water entering the shower is much colder so the shower reduces flow even more than "normal"

 

[twonky]

Hi scoobydo, thanks for the reply. I understand the cold weather will make things worse because of the inlet water temperature being even lower, but this has been an issue since I moved in and was much the same over the summer months.

 

[scoobydo123]

Probably as good as it gets. A combi boiler is around 24kw upwards you are putting in 1/3rd of the power. A 24kw boiler flows around 10lpm so expect around 1/3rd of that remember nothing is 100% efficient either so these figures need adjusting as well so just very rough and ready but may give you an idea.

 

[kbdiy]

Could this be an issue with scaling? Don't know what the water hardness is like in your area but the unit might be suffering.

 

[twonky]

Hi kbdiy, thanks for the reply.

We do have very hard water here (south-east coast) so limescale is an issue with kettles, toilet bowl, etc. If scaling was the issue with my shower though, wouldn't it affect the flow rate out the shower regardless of temperature? At the moment, cold setting is very strong, warm is poor, very warm is not much more than a depressing dribble.

 

[seco services]

You say your shower is warm does it not get hot at all ?

 

[twonky]

Sorry, my poor choice of words, I should have said hot rather than warm. I usually have it on around the 6 mark which I find to be a nice, comfortable showering temperature. If I put it on 10 it would probably burn me if it wasn't just a dribble coming out.

 

[Charnwood]

I usually have it on around the 6 mark which I find to be a nice, comfortable showering temperature.

Sounds about right for an electric shower.

Turning the big knob does not affect the heat setting on the shower's heating element, that's the function of the small knob. The big knob affects the flow rate.

Turn clockwise and the flow slows and the water spends more time in the heater, therefore gets quite hot.
Turn anti-clockwise and the flow speeds up, therefore the water is in the heater for less time, therefore coming out cooler.

 

[seco services]

I usually have it on around the 6 mark which I find to be a nice, comfortable showering temperature. If I put it on 10 it would probably burn me if it wasn't just a dribble coming out.

That's right it's working as it should.

 

[xr4x4]

We have a 8.5kw shower, not great but it's ok.

I assume the head isn't blocked?