3 phase installation for power shower

[mickbristol]

Hi all,
I describe my plans, but i could be really wrong so please stop and advise me...
i live in a bungalow and got a standard electrical shower which i would love to change to a power shower.

i dont have any gas and got an old vented boiler installed, so i was looking for an instantaneous instant electric water heater as i wouldnt like to heat a full boiler for just a shower/tap, as the heating is electric..
i found very good ones from Stiebel Eltron, but they require a 3 phase 400v. which i am not sure i have.
first question, how to find out ? i got access to my meter and electric box but not 100% sure how to identify it...
if i dont have it, then what could be the cost to buy a single phase to 3 phase inverter? i had a rough idea on ebay, and to deliver up to 27kW to the Stiebel instant boiler...it would cost me ... 2 000 pounds !! ???

i am not looking to spend 200 pounds in total as i know it will be more expensive than that. but am i looking for something out of my league ? should i give up the idea of a power shower with instantaneous heating ?

thanks for your help

 

[Brightspark2]

You dont need a 3phase water heater!!! lol


If you dont want an electric boiler, you could get an electric power shower and a water heater for the tap you only need a small one though, nothing industrial size...

 

[mickbristol]

hiya, thanks for your reply
yes i have already installed a small undersink boiler as the pressure for the hot water was too low, so i could do the same for the other tap in the bathroom.
but the electrical shower i have is taking 10k and the water flow is nowhere near a power shower, so i thought i had to get around 15kW at least to have a power shower.

have you got any sugestions for power electrical shower ? which flow rate, what pressure ?

thanks again

 

[Deleted member 26818]

There are some instantaneous water heaters, that are supposedly designed for two-three sinks or one sink and a shower.
Redring is one company that springs to mind.

 

[kingeri]

Don't go installing anything, you're not qualified! Your supply and main fuse need checking to see if they can handle a 15kW appliance. Get an electrician in! (please)

 

[UNG]

Do you have low mains water pressure, if you are looking for a more powerful shower then you would need a cold header tank and a shower pump to supply the water pressure needed for your existing 10kw shower

 

[mickbristol]

oh yes dont worry i will get a professional to install this. i have done an undersink boiler as it was only from a 13 amps socket wiring.
other problem i have with electrical shower is that they look "cheap" in yout shower, i would rather have something which looks like a normal shower... lol
i am giving up the idea of a 3 phase, i have seen my mains supply and can see only 2 big cable so...

so you think 10kw would be enough to heat water at 7 or 8 liters per minute ? mmm sounds a bit just for me, but im not expert at all

 

[mickbristol]

the pressure is around 6 bars, as i had to fit a High pressure relief for my undersink boiler, i think that shoudl be more than enough?
im new owner of this house and the old ones said the electric shower is not very old... but sure there must be something better on the market for 10kw ?
what kind of flow shall i expect for 10kw for let's say heating from 15 degC to 35 ?

 

[UNG]

Sounds to me that the shower is faulty what make is it

 

[mickbristol]

it's a mira zest
just done a few measurments, i have 4 liters per minutes heated from 15 to 35 deg C for 9.3kW
...

does it sounds ok ?

 

[BroadReach]

Hi

4l/min = .07l/s which with a 20 deg C rise would be about 5.8kW. Sounds like the heater is up the chute.

Or another way 4l/min with 9.3kW should give a delta T of about 32 deg C

 

[mickbristol]

oh i see, i dint know the formula...
i shall have a look at the shower heater then, is there any particular maintenance to do ?
thanks very much

 

[BroadReach]

The formula is:

kW = water volume (m3/sec) x density of water (kg/m3) x specific heat capacity of water (kJ/kg K) x Delta T (K)

Density of water is 1000kg/m3 and specific heat capacity of water is about 4.1813kJ/kg K

Better and easier to clamp the supply cable.

Better still get a sparky in?

 

[mickbristol]

i got it,
so for the same temp rise of 20 degC, if i buy this Redring 12Kw instantaneous water heater, it should give me about 8.6 liter/minutes ... that should be ok for a power shower ?
i would have thought the heating transfer from the resistive load to the water depended a lot about the conductive surface between those 2 ?

 

[Knobhead]

Thanks for the formula. Another one to add to the library.

 

[Mark_Burgess]

oh i see, i dint know the formula...
i shall have a look at the shower heater then, is there any particular maintenance to do ?
thanks very much

Your 10kW shower should be pretty good, does the shower head have large holes in it or a nice fine jet out of each?
As for maintenance, if you are in a hard water area, it may need de-scaling.

 

[Englishsparks]

Hi all,
I describe my plans, but i could be really wrong so please stop and advise me...
i live in a bungalow and got a standard electrical shower which i would love to change to a power shower.

i dont have any gas and got an old vented boiler installed, so i was looking for an instantaneous instant electric water heater as i wouldnt like to heat a full boiler for just a shower/tap, as the heating is electric..
i found very good ones from Stiebel Eltron, but they require a 3 phase 400v. which i am not sure i have.
first question, how to find out ? i got access to my meter and electric box but not 100% sure how to identify it...
if i dont have it, then what could be the cost to buy a single phase to 3 phase inverter? i had a rough idea on ebay, and to deliver up to 27kW to the Stiebel instant boiler...it would cost me ... 2 000 pounds !! ???

i am not looking to spend 200 pounds in total as i know it will be more expensive than that. but am i looking for something out of my league ? should i give up the idea of a power shower with instantaneous heating ?

thanks for your help

STOP dont do a thing!!! go get some proffesional help.

you wouldnt like me a proffesional electrican doing some surgery on your body would you??? NO you would like a Surgeon for that.

We go to college for three years, learn the trade and then get the blame because an electrical fault has started a blaze. "Caused because a so called DIYer has been medling again. DO you really know the danger you are putting yourself and your family in?

 

[Engineer54]

STOP dont do a thing!!! go get some proffesional help.

you wouldnt like me a proffesional electrican doing some surgery on your body would you??? NO you would like a Surgeon for that.

We go to college for three years, learn the trade and then get the blame because an electrical fault has started a blaze. "Caused because a so called DIYer has been medling again. DO you really know the danger you are putting yourself and your family in?

Unfortuately, these day's it's more like 17 days!!! lol!! ....But i agree with your overall point!! :redface: lol!!

 

[ian.settle1]

i got it,
so for the same temp rise of 20 degC, if i buy this Redring 12Kw instantaneous water heater, it should give me about 8.6 liter/minutes ... that should be ok for a power shower ?
i would have thought the heating transfer from the resistive load to the water depended a lot about the conductive surface between those 2 ?

As already said you need to find out what your supply capacity is before you start putting in large kilowatt equipment as if they all kick in together you will be calling out the DNO to replace the supply fuse.

 

[UKMeterman]

Hi,
A better idea, check what FLOW you can get from the cold tap, is it about 18L a minute or more? If so get a plumber to fit an unvented hot water cyliner Ultrasteel Unvented Cylinders this has a normal imerssion heater to heat up the hot water and then it is dellivered at the same pressure and rate as your cold water. NB This MUST be fitted by a profesional pulmber, if it were to explode then you would demolish your house..

 

[Knobhead]

Blaster Bates & Son
Plumbing engineers and demolition contractors.
View attachment 12409

 

[mickbristol]

hi and thanks for your replies,
of course i wouldn't fit a big electric supply on my own. was just an idea but i quickly realised how insane it was.
back to my shower, i have measured twice and i have about 8.5 liters per minute at cold temperature. which is about 16 deg C at this time of the year.
i tried again to measure via the shower and got a small 4.5 liters per minute at 41 degC.
i am waiting to received an instantaneous water heater of 12kW. i know it's a good hight current and need a 50 amps circuit breaker with thick cables...
but i will give it a try. i will disconnect the bathroom taps and supply it via the water heater see what the flow is like before rebuilding the shower...
i hope that will be good enough as i wouldnt like to use a system with storage water (not a lot of space available, energy waste etc...)
so ill updated my progress shortly..
but thanks again for your messages

 

[Engineer54]

A 12KW shower, the mind boggles!!

I'm sure Tel will have to get one of them now!! lol!!! mg_smile: :blush5:

 

[jaresquire]

He probably needs it..

 

[mickbristol]

who is Tel?

 

[Engineer54]

who is Tel?

''telectrix'' He just love's big Shower units, the more/higher the KW rating the better!! lol!!! :sifone:

 

[Rick0rz]

I personally dont think you can compare a electric shower to one off a boiler, big electric shower 11kw.. my shower at home off a 35kw combi along with great water pressure = removes grout from tiles

 

[mickbristol]

hello
i think you are right... i have started by cleaning my 8.5kW shiwer to make sure it wasnt faulty, and i def cant get more than 4.5 L/m so i doubt a 12kW will give me 8 or 9 L/m.
i correct my old thread but i guess everybody guessed. i want a "powerful shower" not a power shower. i know a power shower needs a pump and a water storage to deliver big amounts of water.
back to my plans, im confused about combi boilers... when i read online i see that combi boilers never run iit of hot water as it heats on demand. so how come in the spec it says it can deliver 8 or 9 L/m for 9kW??? did i read it wrong? also why some combi boilers also specify a capacity like 210 litres? i thought it heats on demand?
i dont have gas and dont hqve radiators, so basically the boiler im looking for must be electric and just for a "powerful shower" with 8 or 9 litres per minutes. i dont have 3 phases supply so i guessed 12kW is the max i can get, am i right?
any advices?

thanks

 

[UKMeterman]

Hi,
How do you heat all your water at the moment? Do you have a hot water cylinder? If you do not have a hot water cylinder, do you have space anywhere, even for a small one? How long do you want each shower to last, what temprature and what is the flow rate at your cold tap.

Once we have this information then we can make suggestions.

 

[mickbristol]

hi,
yes i have a vented cylinder, i guess 100 litres, and a water storage in the loft.
as the kitchen tap was a bit far away and very low flow rate, i put a undersink water heater, so my cylinder is now only used for the bathroom tap (bit waste i guess)
i have room for a boiler but i was ideally thinking of having no water storage, and an instant heater to save energy and water. but before that i mainly want a powerful shower so i guess it will be one or the other ? ...
i would like instant heating as i would like to have a shower at any time of the day (without heating the water for the whole day)
my showers are on average 10 minutes, but if i could reach 20 or even unlimited, that's perfect
my cold water can deliver easily 8 litres/minute, i have fitted a valve pressure reduction for my undersink heater, i have limited to 4 bars, so i guess i could have more than 8 litres/minute without it.
thanks

 

[UKMeterman]

Hi.
So get the cylinder changed for an unvented modern one, they have very little heat loss, and then replumb to have a mains pressure shower. The cylinder is then heated over a longer period with a 3Kw heater.

 

[mickbristol]

sorry im pretty new and rubbish with heating systems... i need more details...
is that mean i can get rid of the water storage in my loft ?
what do you mean by replumbing?
thanks

 

[UKMeterman]

Hi,
Yes the tank in the loft can go, you will need a new mixer valve, and if you buy the right cylinder you have the option in the future to have solar to heat the hot water directly.

 

[mickbristol]

looks like the safest and better option eould be a thermal store? would you agree? but looks like there will be a limited amount of hot water available?
is there any other type of boiler that can deliver unlimited hot water at main pressure?

 

[UKMeterman]

looks like the safest and better option eould be a thermal store? would you agree? but looks like there will be a limited amount of hot water available?
is there any other type of boiler that can deliver unlimited hot water at main pressure?

It takes a lot of energy to heat water, look up the specific heat capacity of water. You do not have enough energy avaliable at your location to heat water at the rate you want on demand. The unvented hot water cylinder I have suggested are now becomeing common in the UK and have been used for many years on the continent. If you do go down the route of the thermal store you need somewhere to put the thermal store and due to the accessories such as the plate heat exchanger you may find it too big.

 

[joe j]

I'm very worried by this thread.

 

[Knobhead]

I'm very worried by this thread.

Just close you’re eyes and think of England.

If this thread worries you there’s even better if you look for them!

 

[mickbristol]

It takes a lot of energy to heat water, look up the specific heat capacity of water. You do not have enough energy avaliable at your location to heat water at the rate you want on demand. The unvented hot water cylinder I have suggested are now becomeing common in the UK and have been used for many years on the continent. If you do go down the route of the thermal store you need somewhere to put the thermal store and due to the accessories such as the plate heat exchanger you may find it too big.

i understand, but i can see some boilers 15kW single phase, surely they can deliver around 10 liters/minutes hot water with heat on demand ? that's all i want
as i understand, a thermal store has hot water in it, and the hot water delivered is only the main cold running through inside the thermal and taking the heat of the warmed water inside.
even if there a combi (that would leave me the option to install radiators one day if i need to)

thanks

 

[UKMeterman]

i understand, but i can see some boilers 15kW single phase, surely they can deliver around 10 liters/minutes hot water with heat on demand ? that's all i want
as i understand, a thermal store has hot water in it, and the hot water delivered is only the main cold running through inside the thermal and taking the heat of the warmed water inside.
even if there a combi (that would leave me the option to install radiators one day if i need to)

thanks

Your Electrics can't supply 15KW if you want anything else connected at the same time, 15KW from GAS is easy to do. If you want stored hot water, or a thermal store have a chat with Albion Cylinders Albion Water Heaters they do Unvented cylinders and thermal stores.

 

[Philpot]

I get the feeling that someone is taking the ............

He is now talking about Gas when earlier he didn't have any. Everything you suggest he just come up with another impractical suggestion. We are just too helpful !!!

 

[mickbristol]

reason is that there are some electric boilers single phase 15k,
no i dont have gas and i never said i had
if i come up with another suggestion, it's because it's all new to me and i am trying to understand things, which is the purpose of this site.
thanks for your contribution Philpot, but im sure you will find plenty of other forums where you can put your mess

 

[Geordie Spark]

I'm really not wanting to get too embroiled in this thread, so I'm only going to offer this one suggestion & here it is: Trianco Aztec Classic Electric Boiler - 12kW | Trianco Electric Boilers | Trianco Classic