Electric shower only produces scolding hot or ice cold in hotter months. Any idea what I can do to fix this or is this normal?

[reoreborn85]

Purchased a house last year (June) and it had an electric shower. This is the first time I'd ever used an electric shower as my previous house had a mixer tap.

The shower has three settings 1: Cold 2: Eco and 3: Max and a temperature knob.

I quickly discovered that i couldn't get a good temperature at all on Eco or max.. It was just HOT. Obviously when i put it to cold it was ice cold.

I planned to replace it when I got my money sorted out and stuck with having baths. When it got to September I noticed I could get a good temperature again. I thought the problem had solved itself and left it. I did replace the hose and the shower head (in September of last year) but apart from that haven't touched the unit/set up.

However, in the past few weeks it's gone back to the way it was but FAR worse. It seems it's either scolding hot on ALL settings except on 'cold' setting where it just turns to ice. (Now i am assuming it'll go back in September/when it starts cooling down)

A quick google says it's common for it to get 'warmer' in hotter months as the mains water is going to be warmer but this is SCOLDING hot. There is no way anybody could stand under it.

Is this truly 'normal'? Or is it something that can be fixed? I'm not expecting perfect temps but at least something you can stand under.

i THINK it's this one but can't be 100%. It looks exactly the same.

ty for any advice

 

[jj4091]

Make and model might help.

 

[reoreborn85]

Make and model might help.

Theres a link to the unit in the bottom part of the comment saying "I think it's this one". as I am not sure. if you're unable to click on said link Its this one "Wickes - Bristan Hydro" but once again im not sure.

 

[jj4091]

 

[endecotp]

It seems it's either scolding hot on ALL settings except on 'cold' setting where it just turns to ice.

Can you try to measure the flow rate? I.e. time how long it takes to fill a jug, or something. Try to measure this with the temperature knob in a few different positions.

What should happen is that when you turn the temperature knob to cooler, the flow rate increases - since the energy input is constant the water will be cooler. But if the flow rate is constrained by e.g. the shower head or the upstream plumbing, then the flow rate won't increase and it won't get any cooler.

 

[reoreborn85]

ty for the vid!


Maybe I am wrong but the video seems to be describing a different issue. This video seems to be for people whose shower goes hot and cold without touching any settings. My issue is it's either COLD or Hot. There is no in the middle nm what settings I touch. It doesn change from hot and cold etc.

Would the valves in this video still be relevant?

 

[reoreborn85]

Can you try to measure the flow rate? I.e. time how long it takes to fill a jug, or something. Try to measure this with the temperature knob in a few different positions.

What should happen is that when you turn the temperature knob to cooler, the flow rate increases - since the energy input is constant the water will be cooler. But if the flow rate is constrained by e.g. the shower head or the upstream plumbing, then the flow rate won't increase and it won't get any cooler.

Ty for the reply!

we have quite a big shower head (hanging over head) so not sure how accurate this will be lol but ive just checked. On the temp knob turned up it takes 22 seconds to fill 1lt jug.

When the temp knob is turned down to cold it takes 12ish seconds. Both are scolding hot. There is def a noticeable difference in water pressure. As I say though both are still scolding hot.

 

[jj4091]

ty for the vid!


Maybe I am wrong but the video seems to be describing a different issue. This video seems to be for people whose shower goes hot and cold without touching any settings. My issue is it's either COLD or Hot. There is no in the middle nm what settings I touch. It doesn change from hot and cold etc.

Would the valves in this video still be relevant?

He doesn't mention adjusting settings because he is talking about the flow rate either not being high enough or varying during use which is what you are experiencing. So yes the valves could be the problem but do the basics first the same as endecotp says. But check your stopcock is fully open first.

 

[jj4091]

You made your last post while I was typing Did you fill the jug with the shower head attached or removed. I'm not a plumber but it would take about 5 seconds max. to fill a 1litre jug from any of our taps. What are the results if you do the same test from a cold tap in the bathroom

 

[reoreborn85]

You made your last post while I was typing Did you fill the jug with the shower head attached or removed. I'm not a plumber but it would about 5 seconds max. to fill a 1litre jug from any of our taps.

Sadly, No the shower head was attached still. 90% of it went into the jug as I was holding it close to the head.
I Just went and checked and from the cold taps it's about 5-6 seconds. The shower was set to ECO mode (If i put it on full i wouldn't be able to even hold my hands under the shower to collect the water) but that is a bit faster but not by much.

 

[Madrab]

An electric shower uses flow, controlled by the big temp control knob, and heating elements (usually 2) to vary the temp @ the shower head. Depending on the power setting, typically it would be - Cold (no heating element) > ECO (one heating element) > MAX (both heating elements) and that sets the level of power running through the heater can's elements

You should be able to regulate the temp to a comfortable one using those 2 variable settings, if you can't then the control isn't working properly or there isn't enough flow to vary the temp.

You do say when you turn the big temp control from cold to hot the flow decreases by ~50% and vice vera? If that's all fine and it's getting too hot then the stat in the can may not be working.

 

[endecotp]

When the temp knob is turned down to cold it takes 12ish seconds [to fill a 1 litre jug]

5 litres per minute.

Say it's a 10 kW heater. Each litre of water receives 12 x 10 kJ =120 kJ of energy.

Specific heat capacity of water is about 4 kJ / kg K (and a litre of water has a mass of 1 kg) so the temperature will be raised by 120 / 4 = 30 degrees. Say the incoming temperature is 15 C (at this time of year maybe) so the temperature at the shower head would be 15 + 30 = 45 C.

Is 45 C scalding?

On the "eco" setting I'd expect it to be something like half that, i.e. 30 C at the same flow rate. (Note when you change from High to Eco you'll need to wait for a few seconds for the temperature to adjust.)

(Someone please check my maths!)


Edit: I now see that your test was on "eco" mode. In which case, I think we need to know whether (a) you have an unusual idea of what "scalding hot" means, which we could perhaps check by actually measuring the temperature of the water you've collected, or (b) your incoming "cold" water is unusually warm.

 

[Diver Fred]

Does the outlet have a swivel on it - ideally at the spray head end? If it doesn't then the inner hose could be constricting the outlet flow. Try changing the hose.
Is there a stop tap for the shower unit - 1/4 turn ones are notorious for being difficult to fully open if not regularly exercised.

Otherwise, the internal wiring of the shower unit needs to be checked. That requires either a Plummer or an Electrician (or a person who can do both) if you don't feel competent to look under the cover.

 

[reoreborn85]

5 litres per minute.

Say it's a 10 kW heater. Each litre of water receives 12 x 10 kJ =120 kJ of energy.

Specific heat capacity of water is about 4 kJ / kg K (and a litre of water has a mass of 1 kg) so the temperature will be raised by 120 / 4 = 30 degrees. Say the incoming temperature is 15 C (at this time of year maybe) so the temperature at the shower head would be 15 + 30 = 45 C.

Is 45 C scalding?

On the "eco" setting I'd expect it to be something like half that, i.e. 30 C at the same flow rate. (Note when you change from High to Eco you'll need to wait for a few seconds for the temperature to adjust.)

(Someone please check my maths!)


Edit: I now see that your test was on "eco" mode. In which case, I think we need to know whether (a) you have an unusual idea of what "scalding hot" means, which we could perhaps check by actually measuring the temperature of the water you've collected, or (b) your incoming "cold" water is unusually warm.

When I say "Scolding" i don't actually mean BOILING i just mean You can't keep your hand under it for more than say 2-5 seconds.

I will admit am sensitive to heat (dreading the next few days due to the weather lol) but my wife isn't. She can literally get into an extremely hot bath thats been made with only the hot tap and loves it yet she can't stand under the shower at it's coolest on Eco. I sadly don't have a thermometer to get an accurate reading.

Using the cold taps all around the house they're normal temps.

 

[reoreborn85]

Does the outlet have a swivel on it - ideally at the spray head end? If it doesn't then the inner hose could be constricting the outlet flow. Try changing the hose.
Is there a stop tap for the shower unit - 1/4 turn ones are notorious for being difficult to fully open if not regularly exercised.

Otherwise, the internal wiring of the shower unit needs to be checked. That requires either a Plummer or an Electrician (or a person who can do both) if you don't feel competent to look under the cover.

I've checked the main stopcock )(fully open) but haven't checked the small one on the showers water supply. I'll give it a few quarter turns. Its currently turned to 12-6 position with the pipe running vertically. ill give it a few turns

I am comfortable with looking under the cover but not entirely sure what I'd be looking for. Am i looking for damaged wires/loose wires from the mains to the unit?