Can you plumb hot water supply into an electric shower ?

01-11-2015 01:41AM

The Sidewards Man wrote: »

Gary how many in the Uk die every year form legionnaires? Bringing the scalding water is irrelevant and confusing.

I don't think it is, for me as a heating engineer it's the two things that have the biggest impact on a home owner when hot water design is looked at, its also something the industry is looking at right now with some arguing similar points to yourself.

But as for deaths there would be none at all at all from legionnaires if fairies like me were listened to also Irish homes are at greater risk than UK homes as hot water cylinders (up until the SEI grants scheme anyway) commonly had no basic controls for temperature allowing a greater risk of legionella and scolding amongst the young and old.

There is a bit of info below (I don't have numbers personally) but again if you no wana listen that's OK.

large buildings, such as hotels, hospitals, museums and office blocks, are more vulnerable to Legionella contamination because they have larger, more complex water supply systems in which the bacteria can quickly spread.
The two things that Legionella bacteria need to grow and reproduce are:
a water temperature of 20-45C (68-113F)
impurities in the water that the bacteria can use for food – such as rust, algae and limescale
Although rare, Legionnaires' disease has also come from contaminated showers, sprinkler systems and spas.
Legionnaires' disease is rare in the UK. In 2013, 284 people were reported to have the infection in England and Wales. Of these cases, 88 people (31%) were exposed to the infection while travelling abroad – mainly to Mediterranean countries, but also tropical countries such as India. However, given the millions of trips made abroad each year, 88 cases is a very small number.
Cases of Legionnaires' disease arising in England and Wales usually peak between July and September.
Increased risk
Everyone is potentially at risk of developing Legionnaires’ disease. However, certain things make it more likely that you will experience a more severe form of the infection. These include:
being 50 years of age or over – 235 (83%) of the 284 confirmed cases in 2013 involved people over 50 years of age
smoking, or having smoked heavily in the past (a recent study has shown that smoking cannabis may also increase your risk)
drinking alcohol heavily
about three-quarters have an underlying medical condition, such as diabetes, kidney disease, or a pre-existing lung condition
having a weakened immune system – for example, people with HIV and AIDS or cancer

evolving_doors · 01-11-2015 01:52AM

dazed+confused wrote: »

There has never been a recorded death from legionnaires disease that was contracted in a domestic building.

It has happened in hospitals, care homes, municipal buildings etc.

There aren't recorded deaths for lots of unsafe things, but that doesn't make the unsafe thing safe.

I think if you are looking for statistics then probably your safest bet would be to ask what are the 'chances' of creating legionnaire's in a certain environment. Going by the NHS info:

The two things that Legionella bacteria need to grow and reproduce are:

1. A water temperature of 20-45C (68-113F)
2. Impurities in the water that the bacteria can use for food – such as rust, algae and limescale.

So we'll assume that the OP has fulfilled criteria 1. then I suppose the next thing to assess is the chances of having rust,algae or limescale present in a heating system.

I'm not a plumber by any means (no means really) so I suppose the only thing to do is ask any plumbers here if they have ever come across rust,algae or limescale in pipework?

The Sidewards Man · 01-11-2015 02:06AM

This argument is weak also the posters who are constantly blowing of their profession thinking they are more qualified than other posters is puerile.

01-11-2015 02:34AM

The Sidewards Man wrote: »

This argument is weak also the posters who are constantly blowing of their profession thinking they are more qualified than other posters is puerile.

But I am more qualified ??? It's what I do for a living, my nephew plays professional rugby I don't tell him how to catch a ball because I've been watching rugby on the telly for 30 years, that would be really silly and he'd punch me:(

It's very very easy to have a opinion when it cost you nothing but when you are working in people's homes like I am taking any risks is not a option even if those risks are perceived to be utter nonsense by those who think they have a better handle on things.

groodyman · 01-11-2015 02:36AM

The thread is whether you can run an electric shower from a hot water supply or not.

The answer is yes. With the risk of scalding if the cylinder temperature is set too hot and "apparently" the minute possibility of legionaries disease.

So it's up to the electric shower owner. If they want to bare the risk for the good powerful shower spray.

I think it is something that can work well for personal preference in a private residence where it can be managed, but not for installation guidelines.

evolving_doors · 01-11-2015 02:38AM

groodyman wrote: »

The thread is whether you can run an electric shower from a hot water supply or not.

The answer is yes. With the risk of scalding if the cylinder temperature is set too hot and "apparently" the minute possibility of legionaries disease.

So it's up to the electric shower owner. If they want to bare the risk for the good powerful shower spray.

I think it is something that can work well for personal preference in a private residence where it can be managed, but not for installation guidelines.

Don't forget the legionnaire's risk.

The Sidewards Man · 01-11-2015 02:39AM

gary71 wrote: »

But I am more qualified ???

As a real engineer are you an actual real one or one of those ones that do a 3 week course and become one of these rgi or Uk equivalent?

01-11-2015 03:06AM

The Sidewards Man wrote: »

As a real engineer are you an actual real one or one of those ones that do a 3 week course and become one of these rgi or Uk equivalent?

What difference would that make to you, the information posted is enough to determine there is a risk.

Your opinions on connecting a shower in the manor mentioned as posted show you don't have experience of things that can go wrong, it's the things that go wrong that tend to teach the most and this is factored in to the opinion of those with more experience but very hard to explain to those who don't.

But to answer your question I am a time served City and Guilds qualified emergency gas service engineer, it was a 4 year apprenticeship, I have worked in the industry for nearly 30 years and the last 12 years I've worked as a boiler manufacturers technical adviser identifying defects with heating and hot water systems across the country, I hope this helps but if not I can still teach you how to throw a rugby ball;) it's all in the wrist.

Wearb · 01-11-2015 03:11AM

@The Sidewards Man

Do you agree that the risk exists?

If yes, then it seems that you think that it's small enough to take that risk.

Then, after reading this thread, you have more information to help you make that decision.

Because I am not a doctor, I can advise you to take a few paracetamol if you have a pain and suffer no repercussions if you die afterwards. But if I were a doctor, I would be subject to an investigation, because I should have known better.

Same applies here, when you read advice from professionals. The advice has to be best practice. We cannot say it's ok, just because very few die from it.

You have gotten good advice and now it's up to you what you do with it.

Most importantly for me; anybody reading this thread, will realise that there are risks assiocatiatedd with connecting a showere that way.

The Sidewards Man · 01-11-2015 03:12AM

gary71 wrote: »

Your opinions on connecting a shower in the manor mentioned as posted show you don't have experience of things that can go wrong, it's the things that go wrong that tend to teach the most and this is factored in to the opinion of those with more experience but very hard to explain to those who don't.

I have not expressed any opinion on connecting a shower in this thread

did I get the winky eye right?

Look up the definition of engineer

The Sidewards Man · 01-11-2015 03:26AM

Wearb seemingly you need to be some sort of an engineer to make your point valid, Gary has made this clear.

01-11-2015 03:44AM

The Sidewards Man wrote: »

I have not expressed any opinion on connecting a shower in this thread did I get the winky eye right?
Look up the definition of engineer

I never said I was good;) I'm not a engineer I'm a service engineer it's what is written on my City and Guilds cert;)

Please feel free to contact British Gas if you wish as they are responsible for the terminology.

anothernight · 01-11-2015 03:52AM

The Sidewards Man wrote: »

As a real engineer are you an actual real one or one of those ones that do a 3 week course and become one of these rgi or Uk equivalent?

For what it's worth, I'm a "real engineer"... with no practical knowledge about any of this stuff.

01-11-2015 04:12AM

The Sidewards Man wrote: »

Wearb seemingly you need to be some sort of an engineer to make your point valid, Gary has made this clear.

Now your being silly, yes I am qualified as are others who have posted on this thread, as someone who is still learning my trade I don't put myself over anybody.
.

I don't think any experienced plumbing poster is going to agree that this type of installation is a very good idea but why should that be such a hard thing to get across?

Guy:Incognito · 01-11-2015 09:54AM

groodyman wrote: »

I think it is something that can work well for personal preference in a private residence where it can be managed, but not for installation guidelines.

And how is the private home owner "managing" the situation? Are they inspecting the internals of the heating system? How are they ensuring the accuracy of the water temperature? are they even doing basic things like cleaning the shower head regularly?

Dtp1979 · 01-11-2015 10:30AM

Guy:Incognito wrote: »

And how is the private home owner "managing" the situation? Are they inspecting the internals of the heating system? How are they ensuring the accuracy of the water temperature? are they even doing basic things like cleaning the shower head regularly?

No, they have a cylinder thermostat set to 60 so when the water reaches 60, it stop the cylinder becoming hotter

Guy:Incognito · 01-11-2015 10:33AM

Dtp1979 wrote: »

No, they have a cylinder thermostat set to 60 so when the water reaches 60, it stop the cylinder becoming hotter

Ah yes, the "fit and forget" the most basic of criteria for some safety form of managing. What could possibly go wrong.

Dtp1979 · 01-11-2015 10:42AM

Guy:Incognito wrote: »

Ah yes, the "fit and forget" the most basic of criteria for some safety form of managing. What could possibly go wrong.

It's better than some fool willingly under heating the water, knowing the risk they pose to themselves and other family members

K.Flyer · 01-11-2015 10:46AM

My biggest concern would be if your immersion element thermostat failed, and they very often do, and the temperature of the stored water was to rise to a dangerous level.
The person using the shower would be unaware of this danger as they would be at first receiving hot water produced by the shower unit itself and heating the water from the pipe-run.
Then the potentially scalding water will arrive at the shower unit and if you are in a shower enclosure, say with your back to the shower unit, those seconds it takes for you to register what is happening and to turn around and reach through the excessively high water temperature to turn off the unit or to direct the shower head away, could be enough time for damage to be done.
Now what if this was to happen to a younger person, or an older person when using the shower, whose reactions are not quite as fast as yours, is it really worth the risk?
This is why there is no instructions in the installation booklet that suggests connecting the water supply to a pre heated water source, because you are now by-passing the safety feature built into the shower unit.

Walter Becket · 01-11-2015 10:49AM

I have done this and it works well. A short pipe run from the cylinder is essential. Care must be taken when setting the thermostatic mixing value. I done it with a triton t90 using a 1/2" thermostatic mixing valve. The shower is on a wall backing onto the hot press, the feed pipe to the hot cylinder is 1" so is the cold feed pipe and generally the pipes are oversized. The thermostatic mixing value takes care of unpredictable water temperature from the hot cylinder. When using any shower the user should let the water flow for a while to allow the temperature to stabilise before getting in the shower and when you think about it this is what we all do automatically. Once the pipe run from the cylinder is short the temperature will stabilise quickly. The risk with this idea is that with a long pipe run from the cylinder the user may think the water temperature has stabilised when in fact warm water hasn't got to the shower from the cylinder yet. The risk of legionnaires is not increased because water is not stored warm. Proceed at your own risk remember this is breaking the rules.

John T Carroll · 01-11-2015 11:13AM

Gebgbegb wrote: »

There aren't recorded deaths for lots of unsafe things, but that doesn't make the unsafe thing safe.

I think if you are looking for statistics then probably your safest bet would be to ask what are the 'chances' of creating legionnaire's in a certain environment. Going by the NHS info:

The two things that Legionella bacteria need to grow and reproduce are:

1. A water temperature of 20-45C (68-113F)
2. Impurities in the water that the bacteria can use for food – such as rust, algae and limescale.

So we'll assume that the OP has fulfilled criteria 1. then I suppose the next thing to assess is the chances of having rust,algae or limescale present in a heating system.

I'm not a plumber by any means (no means really) so I suppose the only thing to do is ask any plumbers here if they have ever come across rust,algae or limescale in pipework?

I've often wondered has there been any recorded health problems with the "normal" pumped (integral) showers which take their feed from a cold water header tank which in the summer can often reach over 20C, I've measured a relatives at 21C a few years ago, it was located in the attic and hadnt been used for a week as the house occupants were on holiday. One could say that any bugs are killed by the shower electric heating element but I wouldnt be too sure of this as the shower water temperature is normally around 38C to 43C and its rarely that anyone turns down the flowrate to increase the water temperature even temporarily, even if one did, the water temperature will never reach 60C due to to the overtemp stat(s) operating to prevent scalding.

Calibos · 01-11-2015 12:59PM

Walter Becket wrote: »

I have done this and it works well. A short pipe run from the cylinder is essential. Care must be taken when setting the thermostatic mixing value. I done it with a triton t90 using a 1/2" thermostatic mixing valve. The shower is on a wall backing onto the hot press, the feed pipe to the hot cylinder is 1" so is the cold feed pipe and generally the pipes are oversized. The thermostatic mixing value takes care of unpredictable water temperature from the hot cylinder. When using any shower the user should let the water flow for a while to allow the temperature to stabilise before getting in the shower and when you think about it this is what we all do automatically. Once the pipe run from the cylinder is short the temperature will stabilise quickly. The risk with this idea is that with a long pipe run from the cylinder the user may think the water temperature has stabilised when in fact warm water hasn't got to the shower from the cylinder yet. The risk of legionnaires is not increased because water is not stored warm. Proceed at your own risk remember this is breaking the rules.

If it's an electric shower which is expecting a cold feed anyway won't it react and lower its heat input once the warmer mixed water from your mixing valve arrives along a longer pipe run. Is the problem that it doesn't react fast enough? ie. That it detects 15deg water and adjusts its heating element and flow rate to input 25deg for a 40deg shower, then along comes 30deg water and now that 25deg input creates a scalding 55deg for a few seconds till the thermostat on the shower reacts.

John T Carroll · 01-11-2015 02:09PM

Calibos wrote: »

If it's an electric shower which is expecting a cold feed anyway won't it react and lower its heat input once the warmer mixed water from your mixing valve arrives along a longer pipe run. Is the problem that it doesn't react fast enough? ie. That it detects 15deg water and adjusts its heating element and flow rate to input 25deg for a 40deg shower, then along comes 30deg water and now that 25deg input creates a scalding 55deg for a few seconds till the thermostat on the shower reacts.

I think most of the "thermostatic" electric showers just automatically control the flow of water within certain limits to give the desired shower temperature, A 9.5 KW electric shower will flow 4.1 LPM from water at 10C to a showering temperature of 43C, if the supply temp was increased to 25C then the flow would need to be increased to 7.6 LPM to maintain 43C showering temperature, I dont think any internal thermostatic control could achieve this without electric heating element control, but I think the point thats been made is that you set up the shower to give say 7.6 LPM (from 25C) and then just wait until the water from the external thermostatic/mixing valve reaches 25C and then pop in the shower, it takes my mains supplied 9.5 KW shower 10 to 12 secs to reach its showering temperature anyway so a few more secs one way or the other wont make a whole lot of difference?

LeBash · 01-11-2015 04:51PM

The Sidewards Man wrote:

Have you links or some vague back up to this Halloween myth?

That's actually pretty much common sense. its been pretty high profile in the news about a year ago in a hospital up north.

The reason it's not all that common is everyone's heating is plumbed in a way to stop it. Also, it's a pretty nasty way to go.

groodyman · 02-11-2015 12:12AM

Fed from the slightly heated cylinder, I now have an electric shower that's as powerful as a power shower. And a much lower energy usage. Delighted with the result. Based on the responses it's clear the risks are less than minimal.

The Legionella bacteria is no more a risk than the original feed from attic tank as this water will get to above 20 degrees in hot summer days anyway. So no difference there.

It's the same for the scalding risk, an electric shower "connected to specs of the manufacturer guidelines" can be set to dispense water hot enough for scalding. so no risk difference there.

Let's not forget the common sense aspect too. Generally people hand test the water in a shower before standing under it.

This modification has worked very well for me by setting up the cylinder to not heat the water above 30 degrees. I've done this by disconnecting the immersion heater completely and only using the gas boiler for 30 mins a day "Which I was doing anyway to supply warm water to the taps". Also the thermostat on the cylinder for the gas boiler is set below 30 degrees. Note: My boiler can heat the cylinder water independently without heating the rads.

Also: Even without heating the water in the cylinder at all, I am getting a very powerful shower just from the temperature difference between the hotpress and the attic.

It has worked out brilliant for me. Each to their own I say. If you don't like the idea don't use it. If you do then go ahead at your own risk.

Dtp1979 · 02-11-2015 12:26AM

groodyman wrote: »

Fed from the slightly heated cylinder, I now have an electric shower that's as powerful as a power shower. And a much lower energy usage. Delighted with the result. Based on the responses it's clear the risks are less than minimal.

The Legionella bacteria is no more a risk than the original feed from attic tank as this water will get to above 20 degrees in hot summer days anyway. So no difference there.

It's the same for the scalding risk, an electric shower "connected to specs of the manufacturer guidelines" can be set to dispense water hot enough for scalding. so no risk difference there.

Let's not forget the common sense aspect too. Generally people hand test the water in a shower before standing under it.

This modification has worked very well for me by setting up the cylinder to not heat the water above 30 degrees. I've done this by disconnecting the immersion heater completely and only using the gas boiler for 30 mins a day "Which I was doing anyway to supply warm water to the taps". Also the thermostat on the cylinder for the gas boiler is set below 30 degrees. Note: My boiler can heat the cylinder water independently without heating the rads.

Also: Even without heating the water in the cylinder at all, I am getting a very powerful shower just from the temperature difference between the hotpress and the attic.

It has worked out brilliant for me. Each to their own I say. If you don't like the idea don't use it. If you do then go ahead at your own risk.

http://drcarlenewentworth.com/wp-content/uploads/2014/11/Bury-your-Head-in-the-sand.jpg

Irish Steve · 02-11-2015 01:20AM

Going back for a moment to the risks, have a quick look at the 2 links that follow, this should be (a) recent enough and (b) specific enough to give an indication of why Legionnaires can be a problem.

http://www.rte.ie/news/2015/1001/731633-hiqa-our-lady-of-lourdes-hospital-drogheda/

There is a clear indication of the issues at this site

https://en.wikipedia.org/wiki/List_of_Legionnaires'_disease_outbreaks

Warm storage water IS a risk, exactly how much of a risk will depend on other factors.

The risks from over temperature due to a failure has also been highlighted.

Yes, running a shower from the hot supply can physically be done, the advisability of NOT doing so has been clearly shown by others.

Have a good look at the table at the end of the Wikipedia page, the ideal temperatures for the growth of legionella is exactly the temperatures that are most commonly used for showering.

32 people died out of a total of 318 infected by a Hot Tub at an exhibition in Holland in 1999. Is that dramatic enough for you? It should be. If you want more, 12 fatalities out of 275 ill in Portugal in 2014, "Source unknown". 12 deaths out of 113 infected in New York in 2015, despite a lot of checks, the source has not yet been determined.

Sleeper12 · 02-11-2015 08:21AM

It's a definite no no. The electric shower is NOT designed for this. Obviously the warranty would be void but so would any home insurance. It's also you could be prosecuted in court.

Walter Becket · 02-11-2015 09:34AM

Calibos wrote: »

If it's an electric shower which is expecting a cold feed anyway won't it react and lower its heat input once the warmer mixed water from your mixing valve arrives along a longer pipe run. Is the problem that it doesn't react fast enough? ie. That it detects 15deg water and adjusts its heating element and flow rate to input 25deg for a 40deg shower, then along comes 30deg water and now that 25deg input creates a scalding 55deg for a few seconds till the thermostat on the shower reacts.

The t90 has no thermostatic control just a hi temp. cut out so it cannot make adjustments to heat imput or flow rate, you can test how fast the hi temp. cutout reacts by turning both knobs to max when the shower is running. There is a "care" version of the t90 with more safety devices built in it's intended for people who have limited mobility or little or no ability to sense water temperature on their skin. It would be worth considering but I'm not familiar with it's internal workings.

John T Carroll · 02-11-2015 09:40AM

Walter Becket wrote: »

The t90 has no thermostatic control just a hi temp. Cut out so it cannot make adjustments to heat imput or flow rate,

Will check out a neighbour's of mine who installed the T90 last week and see what the score is. There are definitely a number of selectable numbered positions on it which I presume just changes the flowrate to give the desired selected temperature, maybe thats just it and there is no automatic adjustment of flow/heating element as you state above, the flowrate is unlikely to change anyway because its a pumped unit.

Can you plumb hot water supply into an electric shower ?

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