Remove tank and install electric water heater

[gijno]

Hello, I want to remove tank from the storage and install an electric water heater to save space and have hot water on demand.
I live in a 1 bedroom flat, so I need to serve only 1 bathroom. At home I have only electricity, no gas.

I was thinking to this solution instead of the tank, Tankless water heater Stiebel Eltron DHE 18/21/24 - CNMOnline .

This can be a good idea? Do you think can I have hot water to the shower and basins? Are those kind of water header expensive in electric consumption?

Thanks to everyone

 

[Ray Stafford]

Thats a 3 phase unit. Do you have 3 phase power in a one bedroom flat?

Instantaneous electric water heating is only really any good for a shower, where the low flow rates don't matter. If you don't have gas, I would keep the tank if I were you.

 

[gijno]

Thats a 3 phase unit. Do you have 3 phase power in a one bedroom flat?

To be honest, don't know. How can I check it?

Instantaneous electric water heating is only really any good for a shower, where the low flow rates don't matter. If you don't have gas, I would keep the tank if I were you.

I'm sorry I do not understand what you said. At the flat I have (very) low hot water pressure, so I was assuming by installing an electric shower heater it'll get water from mains (which has a good pressure). Is my assumption right?

I was thinking to remove tank even to free some space into the storage in order to use it as a real storage and not only as a "tank room".

 

[Ray Stafford]

Hi Gijno

To be honest, my question was tongue in cheek - you won't have 3 phase electricity in a one bedroom flat, so that unit is out.

You are confusing pressure with flowrate.

To heat water, you need kilowatt hours. The amount of kilowatts you need depends on the incoming water temperature, the number of degrees you want to heat it by, and the amount of water (flow rate, expressed in litres per min) that you want to heat.

Very roughly speaking, about 9 litres per minute is the thresshold below which filling a bath becomes unbearably slow. If you are patient, you can probably tolerate as little as 5-6 litres on a basin or sink tap.

You need about 24 kilowatts to generate 9 litres per minute of hot water at a temperature rise of 35 degrees, which is why so many entry level gas combis are 24kw. Most people prefer 30kw, but no-one bothers to make one smaller than 24kw.

The most you will get out of an instantaneous electric device is about 10.8kw (I think that 11kw it the max load on a single circuit on a domestic supply, but you would need to check that with a sparks).

10.8 kw is ok for a shower, but useless for anything else. If you put a decent flowrate through it, the water will only be heated by 15 or so degrees, which is no good - barely tepid at this time of year.

You therefore need to store hot water, or have a gas appliance that can deliver enough kilowatts to give a decent flowrate.

 

[gijno]

Hi Gijno

To be honest, my question was tongue in cheek - you won't have 3 phase electricity in a one bedroom flat, so that unit is out.

Thanks for your honesty. I did not know that.

You need about 24 kilowatts to generate 9 litres per minute of hot water at a temperature rise of 35 degrees, which is why so many entry level gas combis are 24kw. Most people prefer 30kw, but no-one bothers to make one smaller than 24kw.

The most you will get out of an instantaneous electric device is about 10.8kw (I think that 11kw it the max load on a single circuit on a domestic supply, but you would need to check that with a sparks).

Here you refer to an electric shower? Or to a device similar to the one I've linked on my first question?

10.8 kw is ok for a shower, but useless for anything else. If you put a decent flowrate through it, the water will only be heated by 15 or so degrees, which is no good - barely tepid at this time of year.

You therefore need to store hot water, or have a gas appliance that can deliver enough kilowatts to give a decent flowrate.

No gas unfortunately. As you suggest to keep tank, is there any solution you suggest to increase hot water pressure? A water pump? Or something else?

 

[Ray Stafford]

Hi Gijno

The type of electric device is irrelevant. A kilowatt is a kilowatt, so ANY instantanous electric water heating device has the same problem - to get a decent flow-rate, it needs a 3 phase supply. The only reason I mentioned a shower is because it is the commonest instantaneous electric water heating device, and most people have experience of them.

Hard to say how best to improve your current set up without knowing more about it - I would suggest getting a good local plumber to have a look. You can post on the forum in the "I need a plumber" section.

 

[gijno]

Hi Gijno

The type of electric device is irrelevant. A kilowatt is a kilowatt, so ANY instantanous electric water heating device has the same problem - to get a decent flow-rate, it needs a 3 phase supply. The only reason I mentioned a shower is because it is the commonest instantaneous electric water heating device, and most people have experience of them.

Hard to say how best to improve your current set up without knowing more about it - I would suggest getting a good local plumber to have a look. You can post on the forum in the "I need a plumber" section.

Thanks for you reply.

I've seen on your website you have a trader in Croydon. As I live in SE8, London, can I arrange an appointment with him? Or you do not cover my area?

 

[Ray Stafford]

Sorry Gijno, we are a plumbing supplies wholesaler, not plumbers, and we are not open to the public.

However, there are plenty of plumbers from the Croydon area on the forum - hopefully one will be along later in the day. Most will be out working at the moment.

Ray

 

[gijno]

All right Ray, thanks so much for your help and time
Have a nice day

 

[gijno]

Sorry Gijno, we are a plumbing supplies wholesaler, not plumbers, and we are not open to the public.

However, there are plenty of plumbers from the Croydon area on the forum - hopefully one will be along later in the day. Most will be out working at the moment.

Ray

Ray, is there any plumber you suggest I can contact?