Can you plumb hot water supply into an electric shower ?

deandean · 02-11-2015 09:53AM

groodyman wrote: »

I've been keeping the cylinder water just luke warm for years, don't need it really hot. Still no sign of legionaries disease.

Ditto. My cylinder stat has been set to 50 DegC for nigh on 20 years, mainly cos the kids kept switching the immersion on.

We've never had a problem with the hot water quality.

I don't buy this legionnaires disease in the hot water cylinder theory.

K.Flyer · 02-11-2015 09:55AM

Unless they have changed the design fairly recently, the thermal cut out only shuts off the power to the heater elements inside the shower unit, it doesn't shut off the flow of water through the unit itself.
So in other words, if excessively hot water is making its way to the shower unit due to a thermal control failure at the supply end, that hot water is going to pass straight through the unit.

K.Flyer · 02-11-2015 11:01AM

deandean wrote: »

[...]
I don't buy this legionnaires disease in the hot water cylinder theory.

You don't have to if you don't want to. .. however,

I am sure these people know what they are talking about..

HSE U.K. Health Services / Legionella

What is legionella?

Legionella bacteria is commonly found in water. The bacteria multiply where temperatures are between 20-45°C and nutrients are available. The bacteria are dormant below 20°C and do not survive above 60°C.

Using temperature control

The primary method used to control the risk from Legionella is water temperature control.
Water services should be operated at temperatures that prevent Legionella growth:

Hot water storage cylinders (calorifiers) should store water at 60°C or higher

hatchman · 02-11-2015 11:28AM

The cylinder in my heat pump has periodic increases to the hot water, every 14 days it increases the temperature to 55c. All other times it keeps the water temp at 41c. Is this sufficient to keep us safe ?

Walter Becket · 02-11-2015 11:29AM

John T Carroll wrote: »

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.

One knob goes from hot to cold and can be set in any position it controls the flow rate the other knob controls the heating elements you can have none one or two working. I think there may be a model that has 4 settings on this knob one of the elements is more powerful than the other so this allows for 3 different power settings and none.

Walter Becket · 02-11-2015 11:47AM

K.Flyer wrote: »

Unless they have changed the design fairly recently, the thermal cut out only shuts off the power to the heater elements inside the shower unit, it doesn't shut off the flow of water through the unit itself.
So in other words, if excessively hot water is making its way to the shower unit due to a thermal control failure at the supply end, that hot water is going to pass straight through the unit.

Yes the thermal cutout doesn't stop the water it only cuts power to the heating elements. I have used a thermostatic mixing valve if it failed completely or had its cold supply cut off then yes 60deg. water could be supplied to the shower. No system is perfect. The best protection is a very short pipe run and always allow the shower to run until the temperature has stabilised. This is not best practice and should only be done if you are willing to accept some risk. Life is a risk.

Wearb · 02-11-2015 11:59AM

Walter Becket wrote: »

I have used a thermostatic mixing valve if it failed completely or had its cold supply cut off then yes 60deg. water could be supplied to the shower.

Would the thermostatic mixing valve not cut off supply altogether if the cold supply was cut off and the hot supply was above it's set temp ?

02-11-2015 01:18PM

deandean wrote: »

Ditto. My cylinder stat has been set to 50 DegC for nigh on 20 years, mainly cos the kids kept switching the immersion on.

We've never had a problem with the hot water quality.

I don't buy this legionnaires disease in the hot water cylinder theory.

Why take the risk

And due to stratification you will most likely find your cylinder is sitting hotter than its set ruining your precise scientific approach.

I can never understand threads like this where good working practice is thrown out the window by choice.

Why second guess good working practice.

What is it your waiting for before you take on board guide lines, manufacturers instructions, regulations, good working practice, a lot of the information given for installing and temperature settings is based on things that have already gone wrong why refuse to learn from it.

Here we're discussing a installation that is not safe but never mind it'll do?

Pretty much every explosion, death, flooding, big or small drama I've been to over the years would of been prevented if good working practice was used.

As for Legionella I personally don't know of any case and like a old flossy I've been around but that's not a good enough reason for me to ignore safety regulations regarding Legionella.

As a apprentice commonly the gas fitters in their 60s who were from a time before fancy gas detectors would try to get me to look for gas leaks using a flame, they'd say similar things like" I've never had a problem, I've been doing it for years" etc..... I decided to never take a risk even a small one the day a experienced gas fitter of 50+ years found his leak and went from under the stairs in to living room without the benefit of using either of the two doors.

K.Flyer · 02-11-2015 02:29PM

I cannot see the benefit in going to all the trouble that some of you are describing.
Would it not have been a whole lot simpler just to fit a Triton AS2000 or a Mira Event instead?

Walter Becket · 02-11-2015 04:33PM

Wearb wrote: »

Would the thermostatic mixing valve not cut off supply altogether if the cold supply was cut off and the hot supply was above it's set temp ?

Yes I've just checked this by turning the cold supply off and yes the mixing valve won't allow any water through. The more we talk and think about it the safer the idea seems.

Wearb · 02-11-2015 05:01PM

Walter Becket wrote: »

Yes I've just checked this by turning the cold supply off and yes the mixing valve won't allow any water through. The more we talk and think about it the safer the idea seems.

While the mixing valve does improve things with that setup, I certainly would not do it by lowering the cylinder temperature.

Sleeper12 · 02-11-2015 05:08PM

"Yes I've just checked this by turning the cold supply off and yes the mixing valve won't allow any water through. The more we talk and think about it the safer the idea seems."

This is what I do for a living. I gave up all other types of plumbing. All I do now is electric showers. We work on very close to a thousand showers per year. I have been Trained by both Triton & Aqualisa. I can not stress this enough THIS IS VERY DANGEROUS. The shower would NOT be used under the manufactures required operating parameters. All you need to do is look at the installation manual. There is always a diagram showing how their shower MUST be installed. This will show a dedicated pipe coming from the cold water tank in the attic & running it directly to the shower. The shower is NOT designed to be installed in any other way. After speaking to both Triton & Mira today they had the same reaction. Their showers have passed British & EU safety standards to be used exactly as shown in the manual. Both Mira & Triton believe it is illegal to install a regular electric shower this way.
As I mentioned before it voids the warranty & differently voids the home insurance policy.

Can I also point out that any replies on this thread from shower installers, plumbers etc all point out how wrong & dangerous this is. Knowing all I know I'd never have a set up like that in my house. I love & care about my family's safety too much to take stupid chances.

antoinolachtnai · 02-11-2015 05:09PM

The last fatal case of legionella in Ireland to my knowledge was in 2003 (see http://www.breakingnews.ie/ireland/inquest-today-into-legionnaires-death-197140.html http://www.irishtimes.com/news/man-died-after-getting-infection-from-hot-tub-1.430443)

But it's not all that rare. There are thousands of cases per year in the US and Europe. Apparently there are around four cases a year that are acquired locally in Ireland. (http://www.hse.ie/portal/eng/health/az/L/Legionnaires'-disease/)

The problem with legionella is that it is often very hard to track down the exact cause (though it was pretty obvious in the above case.) It doesn't show up very often, but when it does it is sometimes fatal because people aren't rapidly diagnosed. If it suddenly shows up on your beat and you didn't exercise best practice, then you are going to feel very very bad (and if you are a professional, you are likely to get sued).

If you install plumbing fittings of any type other than in accordance with the manufacturers' instructions, then you are taking a risk, and you have to decide for yourself whether it is a needless one.

Walter Becket · 02-11-2015 05:10PM

Wearb wrote: »

While the mixing valve does improve things with that setup, I certainly would not do it by lowering the cylinder temperature.

Absolutely it's a completely unnecessary risk to take

John T Carroll · 02-11-2015 05:12PM

hatchman wrote: »

The cylinder in my heat pump has periodic increases to the hot water, every 14 days it increases the temperature to 55c. All other times it keeps the water temp at 41c. Is this sufficient to keep us safe ?

"Hot Water storage cylinders should store water at 60C or higher" and "Cold Water should be stored and distributed below 20C". I utilise my Solar Controller to control the hot water cylinder temperature at 60C via a second relay and a coil motorised valve, there is a facility, if enabled, which "Every Saturday at 0100 hrs the storage tank is heated once to a temperature of 65C if this temperature was not reached during the previous week". This would very clearly imply, in my opinion, that 60C should be the minimum stored hot water temperature. Of course, as I posted previously, it raises a question mark over the legality of the integrally pumped electric shower which takes its water from a header tank which cannot be guaranteed to be less than 20C and as well as that the shower discharge temperature will never reach 60C, again a very small risk but where does one draw the line??.

antoinolachtnai · 02-11-2015 06:01PM

You can't cover for every eventuality. However, you can follow best practice. That is probably where you draw the line. There is certainly a risk with use of tanks for non-potable water. In our climate, it is probably a small enough risk (but I don't really know).

In the case of the solar controllers, the manufacturers have conducted their own risk assessments and are taking responsibility for what they ship. That is what you are really relying upon.

The risk of scalding is obviously a risk which needs to be considered too.

As I understand it, it isn't really about the temperature of the water itself. It's the biofilm on the surfaces in your tanks and pipes that is where the legionella incubate. The idea of the heating (as I understand it) is to sterilise or reduce the formation of this biofilm. Heating every cubic centimetre of water that goes out the shower isn't warranted.

Wearb · 02-11-2015 06:10PM

John T Carroll wrote: »

but where does one draw the line??.

The place where the line gets drawn keeps changing as knowledge and technology keeps improving. Many many years ago, when I did a bit of plumbing, there was no mention of earth bonding, but now everything is bonded. Equally, a lot of speeding accidents, could be prevented if we lowered the limit to -let's say- 50 kph. Of course this isn't practical, so we have a higher limit that we tolerate. We don't have a limit of 200kph, because we consider that intolerable.

Point I am making is that we tolerate the small risk using the shower water from the storage tank, but we do our best to make sure the cylinder is made safer, simply because it is reasonably possible to do this. Time may come when we have new rules for those showers. Sadly, these sort of regulations are usually driven by a tragedy somewhere.

K.Flyer · 02-11-2015 06:17PM

Wearb wrote: »

[...]Sadly, these sort of regulations are usually driven by a tragedy somewhere.

The words "Titanic" and "Lifeboats" immediately came to mind.

vrrv · 02-11-2015 06:19PM

No way it is very dangerous!

Walter Becket · 02-11-2015 08:03PM

This is what I do for a living. I gave up all other types of plumbing. All I do now is electric showers. We work on very close to a thousand showers per year. I have been Trained by both Triton & Aqualisa. I can not stress this enough THIS IS VERY DANGEROUS.

We're only talking were not driving the wrong way down the motorway. This is how we learn and figure things out who knows perhaps a shower manufacturer is designing a shower that will do this job if they were I'd say the conversation might not be much different to parts of this one. It has been said by most of us already that this is not best practice and breaking the rules but this should not stop us discussing the subject. May we will come up with a fool proof way to do it.

deandean · 02-11-2015 08:40PM

Good points Walter Beckett. IMO this type of discussion is good, and interesting.

I have little time for those who shout XYZ is ILLEGAL because tbey have read it somewhere or were told so by others.

An instant electric shower will work with a much bigher flowrate if the incoming water is warmer. There is no reason why the installation should be legal with incoming water at 19DecC and illegal at 21DegC.

I am going to connect my instant shower to the hot water supply next weekend. Again it's only a 10 minute job for me.

I am all for modifying things. Last mod I did here I doubled the heat outlet of my insert stove. Probably 'illegal' too. But I am warm.

Calibos · 02-11-2015 09:35PM

But hasn't most of this thread been explaining exactly why it is legal at 19c and illegal at 21c....because legionella starts thriving at 20c!!

Side note. I don't understand why Walter Becket thanked that post when I thought he was arguing about the dangers of not following best practice and manufacturers installation instructions???

Calibos · 02-11-2015 09:49PM

With regard to 21c+ water coming from the attic cold water storage tank and the dangers that presents with no protection against it. It's actually probably one of the many reasons why tank insulation, tank lids, attic space cross ventilation etc are now mandated. ie. slow down the heating of the attic space during the Summer long enough that the tank water never gets that warm before Sunset. If it takes 7 hours say for the attic to get to 50c in a baking July day due to those measures and would take another 10 hours for that sustained 50c to heat up the large volume of tank water to 21c, then it's night time before that happens and the tank water never makes it to 21c on any given Sunny Summers day. Obviously there's other reasons for those measures (freezing pipes in Winter, dry/wet rot etc) but I'd say the water tank summer temp issue was one of the ticks in the boxes when the regulators were deciding best practice for attic/roof detailing ventilation and construction.

Walter Becket · 02-11-2015 10:42PM

Side note. I don't understand why Walter Becket thanked that post when I thought he was arguing about the dangers of not following best practice and manufacturers installation instructions???[/quote]

No I'm arguing for a open discussion and inquiry also testing what we say in the real world. I am careful to point out that this may break rules so on your own head be it . ie don't come crying to me if it doesn't work out. I'm not saying we should not break the rules that's up to individual. I was thanking him because I felt he defended me.

John T Carroll · 04-11-2015 05:35PM

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, 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.

Yes, this is the version the neighbour has, it has all sort of bells and whistles....Timed Shutdown, (5,10,20,30 mins)....Phased Shutdown, when the Stop button is pressed, it bleeps twice and cold water only is pumped through the unit for 7 secs......it has one "fixed" 5.25 KW heating element and one "Triac" controlled (by an outlet temperature thermister) 3.25 KW heating element or in the case of a 9.5 KW unit, 1X5.25 KW + 1XTriac controlled 4.25 KW elements. That shower will/should certainly give very tight control of the showering temperatures, all the details are on their website. I certainly wouldnt advise connecting this to your hot water cylinder even if it is a vented one (low pressure) but interestingly enough most of the normal showers I looked at can take inlet water up to 28C.

Walter Becket · 04-11-2015 06:06PM

John T Carroll wrote: »

Yes, this is the version the neighbour has, it has all sort of bells and whistles....Timed Shutdown, (5,10,20,30 mins)....Phased Shutdown, when the Stop button is pressed, it bleeps twice and cold water only is pumped through the unit for 7 secs......it has one "fixed" 5.25 KW heating element and one "Triac" controlled (by an outlet temperature thermister) 3.25 KW heating element or in the case of a 9.5 KW unit, 1X5.25 KW + 1XTriac controlled 4.25 KW elements. That shower will/should certainly give very tight control of the showering temperatures, all the details are on their website. I certainly wouldnt advise connecting this to your hot water cylinder even if it is a vented one (low pressure) but interestingly enough most of the normal showers I looked at can take inlet water up to 28C.

It sounds like it wouldn't take much for triton to make that shower take hot and cold water it would make for a very versatile unit. But in combination with a thermostatic mixing valve it's a great set up.

K.Flyer · 04-11-2015 07:34PM

Walter Becket wrote: »

It sounds like it wouldn't take much for triton to make that shower take hot and cold water it would make for a very versatile unit. But in combination with a thermostatic mixing valve it's a great set up.

AS2000XT Thermostatic Power Shower

Product Description

The AS2000XT thermostatic power shower is ideal for low pressure systems. Designed for use with gravity fed hot and cold supplies, the integral pump provides a powerful shower.

Also perfect for families and the elderly who are looking for extra reassurance, the shower's thermostatic control ensures that the temperature is consistent.

Extra Safety and Comfort

Your selected water temperature remains constant as long as there is hot water in your cylinder. The AS2000XT Thermostatic achieves this through its thermostatic temperature control, which compensates for any changes in water temperature to the shower, caused by hot or cold spots in your hot water cylinder.

Walter Becket · 04-11-2015 07:59PM

Your missing the point a pumped electric shower supplied with water by a thermostatic mixing value allows you to have a heigh flow of water when there is hot water available but you can still have a shower when the cylinder is cold. I've seen houses where they have a shower fed from the cylinder and an electric shower in the same cubical.

BarryD · 04-11-2015 08:03PM

Wait till metered water charges come back and yous all be converting the showers back to the cold feed.. to reduce the flow rates!

Interesting discussion but one thing I don't understand is that surely there's no energy saving for someone who is heating their cylinder daily by immersion - that's using electricity. The instant shower only uses as much power as is needed for the shower. You'd actually use more power heating by immersion (unless night rate maybe), letting it cool and then reheating in shower. Different if you have solid fuel, though that uses energy as well, but in latter case you may as well have a standard mixer running off the HW and CW?

enfant terrible · 04-11-2015 08:26PM

BarryD wrote: »

Wait till metered water charges come back and yous all be converting the showers back to the cold feed.. to reduce the flow rates!

Interesting discussion but one thing I don't understand is that surely there's no energy saving for someone who is heating their cylinder daily by immersion - that's using electricity. The instant shower only uses as much power as is needed for the shower. You'd actually use more power heating by immersion (unless night rate maybe), letting it cool and then reheating in shower. Different if you have solid fuel, though that uses energy as well, but in latter case you may as well have a standard mixer running off the HW and CW?

If the heating is on anyway to heat the house then the hot water cost nothing no?

Can you plumb hot water supply into an electric shower ?

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