Electric Boilers / Electric Central Heating Boilers – 0.5kW to 45kW

Electric Boilers – With over 2 million homes in United Kingdom at present are without a mains gas network supply, also many older houses have flue restrictions or are listed buildings that prevent the use of a gas or oil boiler on site. In these situations an electric boiler can be the perfect solution to your central heating needs.Some of the benefits of electric central heating boilers are that they fairly small and compact, so can often fit in a kitchen cupboard or under the stairs etc. The other great benefit is there’s no flue pipe required, unlike an oil or gas boiler which require a flue pipe to evacuate the products of combustion i.e. the flue gases. Thus, there is no risk at all of CO2 poisoning from a faulty flue system or the boiler when you use an electric boiler system. This requirement for no flue pipe, often allows you to install you electric central heating boiler in the appropriate location, to suit your requirements, which is often not the case for a flued gas or oil boiler

Electric Boilers – What are they ?

Electric boilers can be installed in small to medium sized flats or houses to produce the hot water for both your heating system and domestic hot water use ( normally via a indirect cylinder for your domestic hot water requirements). The most commonly installed boilers either use gas or oil to heat the water, an electric boiler will heat the water via an electric element or multiple elements. They are a popular choice for flats and homes where gas is not an option and oil is either impractical or too expensive. They tend to be limited limited as to the amount of Domestic Hot Water (DHW)  they can produce instantly therefor we always recommend using an indirect hot water cylinder for the domestic hot water, especially if the property has a bath fitted.The smaller boilers , i.e. from 0.5 kW to 15 kW outputs the electric boilers are available in 240 volt , Single Phase , after 15 kW the units require a Three Phase power supply.They are often fitted in new build homes and flats as they are cheaper to install and maintain. Also, with no gas emissions, they are seen by many as a more environmentally friendly choice, as the electric power supplied can be from renewable sources such as wind, solar or tidal electric production.

Advantages of Electric Boilers

Economical

Can be integrated with PV panels to yield further energy savings

Cheap to buy as Electric Central Heating Boilers have no gas valve, fan, air pressure switches, Ignition PCB’s, Ignition leads, electrodes, or burners which keeps the cost down

No yearly servicing is required

No yearly Gas Safe Certificate in relation to rented properties

Cheaper to install

Installing an electric boiler is simpler than gas or oil and so is quicker and cheaper , also as there are no waste gases an electric boiler doesn’t need pipes, flue or chimney so the installation of the boiler will cost you less.

Does not require an external wall for mounting the boiler

High efficiency

As electric boilers don’t need to burn fuel to produce heat they don’t lose energy through waste gases or flues. In many cases this results in efficiency rates of 99% compared to 89 – 95% for most gas or oil boilers

Quiet

Electric boilers are almost completely silent as there are no moving elements within the boiler

Light and compact

They lack waste gases and thus any flue / chimney means the unit is much more compact and light ensuring you have more flexibility about where in the property you have it installed.This makes them much more versatile in terms of where they can be placed in the property.

Easier to maintain

No annual landlord gas safety certificate is required

Unlike gas and oil boilers which have more mechanics included, electric boilers don’t need annual servicing to keep them functioning

Saftey

No carbon monoxide threat to the people within the property

No CO detectors are required

Totally safe when the boilers are protected by RCD & MCB

No condensate pipes to freeze up

Electric Boilers – Things you need to Consider and Know

The biggest and most important issue with electric boilers is not the boilers themselves, it is the power that they require to operate

Firstly you need to –  What’s the difference between a single-phase or three-phase electricity supply ?

Both of these are electricity supplies, it’s the amount of power that is different. A single phase supply is smaller than a three phase supply meaning you cannot use as much power. A typical house will need a single phase supply whilst a larger house, blocks of flats or commercial building will need a three phase supply.

The way to tell what supply a property has is by looking at the fuse on the service head. Single-phase has one 100 Amp fuse ( Although in some older properties this may be a 60 Amp fuse, bit it’s quite rare ) and a three phase supply has three 100 Amp fuses.

So a UK home typically has a 100 Amp supply fuse , this means that all the home electrical appliances , whilst being used simultaneously should not draw over 100 Amps , otherwise the fuse can blow.

Following is a chart showing the electrical ratings of commonly used household appliances –

Firstly Electric Showers- these can have some high loads

Standard Shower Rating Watts (kW)          Maximum load from the supply (Amps)

6kW                                                                      26

9kW                                                                     39.13

9.5kW                                                                  41.3

10.5kW                                                                45.65

11.0kW                                                                47.82

Domestic Electric AppliancesAmps Used
Laptop0.5
Mobile phone charger0.5
Kettle13
Satellite TV box0.5
Printer0.5
Radio0.5
Radiator8.5
DVD player0.5
Hair dryer10
Landline cordless telephone charger0.5
Computer monitor0.5
Desktop computer3
Television 42″ HD0.5
Games console0.86
Washing machine10
Toaster9
Tumble dryer11
Dishwasher10
Iron12.5
Microwave4.5
Vacuum cleaner9
Radiator (oil filled)13


UPDATE – We have now solved this common problem
So why does this matter ? Well it matters because the larger the electric boiler you go in size , the more Amp’s you need available to power the boiler . You will generally find that in a standard 100 Amp – 240 Volt , single phased supply property , the largest boiler you can use is a 10 kW Boiler ( now a 15kW boiler-see the update below in red ) – why ? because this boiler will draw 45.5 Amps , which is getting close to half of the supply for a standard UK property , even when you consider a diversity factor ( which in layman terms means that not every electrical appliance would be on at the same time ) you are starting to possibly exceed your supply and tripping out fuses etc.

We now do a new range of electric boilers for central heating and / or domestic hot water, designated the “FHEL” range that can now utilise what we are calling the ” maximum current watcher” – it is basically a releasing relay (restriction of current). The relay monitors and controls the electric voltage in the whole house or flat and in the case of exceeding the permitted values of the electric current it reduces the input power of the electric boiler. All of this is done automatically, without any human intervention needed.This system will not only operate on our 240 volt / 1 Phase Electric boilers , but also our 400 Volt / 3 phase units as well. This now means that you can use our 15kW electric boiler model, in a property or flat with standard 240 volt, single phase with no worries or problems that the unit will trip out the main electric board.

For full details on this maximum current watcher, please download the following data sheet / instructions

Maximum Current Monitor – Instructions- for electric central heating boilers from Flexiheat UK

What are my other options? Well the best solution would be to get your electrical supply upgraded to Three Phase – Is it possible / How much is it to do this? I don’t know , we just supply the boilers – please contact UK Power Network , who are responsible for this here

Or another option may be to get a second 100 Amp supply to your property – Again , contact UK Power Network on the link above – this option may well work out cheaper than having three phase supplied to your property, but again don’t contact us about this, we just supply the electric boilers and this is not our remit.

Electric Central Heating Boilers – Features & Benefits

All of our “FHEL” range of  Electric Central Heating boilers benefit from –

  • Option to produce domestic hot water via an external indirect cylinder / calorifier and 3-way valve
  • An inbuilt energy saving pump ErP compliant heating pump
  • Pump Anti-Block Function – Regular spinning of the pump (once every 24 hours) prevents potential clogging of the pump during extended boiler down time
  • Very quiet operation due to selected switching relays
  • Anti-Freeze protection system – ensuring that these electric boilers are protected against freezing and any potential damage.
  • Option to monitor the maximum current drawn to prevent overloading of the consumer board in the building/property – this system reduces the input power to the electric boiler automatically – ensuring that your main fuse does not blow.
  • Soft start function – This ensures gradual heat-up of the heating system which is therefore protected against an abrupt temperature rise in the central heating system, that can cause noise due to the expansion of pipes.
  • Balanced service load of heating elements – The microprocessor controller measures the operational time of individual heating elements and actuates them in a manner which ensures a thermally balanced loading of the boiler and an even service load of the heating elements, which extends their operational life.
  • Each boiler is tested – on water circuit tightness and the function of the regulating and safety components is set and tested as well, before it leaves the factory.

The Standard Range 

The Standard Series of electric Central Heating Boilers -The standard range is available in 7.5kW,15kW,22.5kW,30kW,37.5kW and a 45kW Output models. This electric central heating boiler range goes from 2.5kW to 45kW of Heating Output. These Electric Central Heating Boilers work up to maximum temperature of 80°C and minimum pressure of 0.5 Bar to maximum pressure of 3 Bar.The feature the following benefits –

  • Fluent regulation ( boiler output ) in low steps of 2.5 kW for the electric boilers up to 30kW, and 5 kW for the electric boilers from 30 kW to 45kW
  • Option to connect the boilers to an  OpenTherm+ thermostat or controller e.g. a nest controller etc ( control your electric boiler on the go, from your phone)
  • Compensated weather control option for boiler – i.e. control / output according to the spatial or outdoor temperature ( a great energy saving feature)
  • Option to connect up to 32 boilers in an intelligent cascade boiler configuration, in order to have increased heating power or output
  • Outputs of up to 15kW, when using a 240 Volt / 1 Phase electrical supply – and up to 45kW when using a 400 Volt / 3 Phase electrical supply ( up to 1,440 kW when used in a cascade electric boilers configuration)
  • All of these electric central heating boilers up to 23kW Output have an inbuilt 7 litre expansion vessel inbuilt, after this size the electric boilers must use an externally mounted expansion tank dependant on system volume and temperature.
  • Option of remote boiler control through SMS messages when fitted with the SMS module
  • Option to monitor the maximum current drawn to prevent overloading of the consumer board in the building/property – this system reduces the input power to the electric boiler automatically – ensuring that your main fuse does not blow.

Please note the following for the for the rated current of these electric boilers – The smaller electric central heating boilers up to 15kW ,can be wired from either a three phase / 400 volt supply or a single phase 240 volt supply – thus on these units you will see two sets of figures for the maximum rated current – the first number “3 x 12” for example on the FHEL8 Model , is the 3 phase Amps – therefore 3 phases , with 12 Amps on each phase. The second figure in the brackets (1×36) is the single-phase Amps – therefore Single phase / 240 Volt pulling 36 Amps maximum for the FHEL8 Boiler.The same applies for the main circuit breaker figures for the boilers – the first figure is if you use 3 phase supply to connect the boiler up , and the bracketed figure i.e. (the number withing here ) is the size require if you use a single phase supply to wire the boiler up.

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Electric Central Heating Boilers – Standard Series From Flexiheat UK

Standard Series – Electric Central Heating Boilers – Technical Data

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Electric Central Heating Boilers – Standard Series- Technical data – Flexiheat UK

Electric Boilers- with touch display

The next option in the Flexiheat UK electric central heating boiler product portfolio is the touch screen range.This range of electric central heating boilers, are available in three sizes – a 4.5 kW output electric boiler, designated the FHEL5, a 9kW output electric boiler , designated the FHEL9 , and the largest unit being the 13.5kW output electric boiler,which is designated the FHEL14.All of this range are suitable for a single phase – 240 volt supply or can also be wired from a three phase -400 Volt supply.This range of electric boilers has all the features of the standard series , with a few notable enhancements,these being –

  1. Simple and intuitive control of the boiler ,due to the well arranged touch display
  2. Fluent regulation in low power output steps by 500 Watts (0.5kW) for the FHEL5 model, by 1,000 Watts (1 kW )for the  FHEL9 model ,and 1,500 Watts (1.5kW) for the FHEL14 model.These lower power outputs ensure that the heating load requirement is appropriately matched. and brings even greater heating efficiency to the wet central heating electric boiler system.
  3. Minimum output of the electric boilers is 500 Watts (0.5kW) for the FHEL5, 1000 Watts (1 kW ) for the FHEL9,and 1,500 Watts  (1.5kW) for the FHEL14 models , which all helps to increase the efficiency of the electric central heating boiler system.
  4. Due to the low minimum performance and the modulation option, these boilers are recommended for low energy houses and passive houses ( ultra low energy buildings )
  5. The modular digital control assures optimal operation of the electric boiler in a way that optimizes electric energy consumption with the rated thermal output of the electric boiler.

Please note the following for the for the rated current of these electric boilers – The smaller electric central heating boilers up to 15kW ,can be wired from either a three phase / 400 volt supply or a single phase 240 volt supply – thus on these units you will see two sets of figures for the maximum rated current – the first number “8” for example on the FHEL5 Model , is the 3 phase Amps – therefore 3 phases , with 8 Amps on each phase. The second figure in the brackets (21) is the single-phase Amps – therefore Single phase / 240 Volt pulling 24 Amps maximum for the FHEL5 Boiler.The same applies for the main circuit breaker figures for the boilers – the first figure is if you use 3 phase supply to connect the boiler up , and the bracketed figure i.e. (the number withing here ) is the size require if you use a single phase supply to wire the boiler up.

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Electric boilers for central heating – “FHEL” Touch Screen Series from Flexiheat UK

Touch Screen Series – Electric Central Heating Boilers – Technical Data

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Electric Boiler for Heating and or Hot Water – FHEL Touch Screen Series from Flexiheat UK

Economic Series of Electric Central Heating Boilers 

Last but not least is our economic range of electric boilers, this range consist of two boilers only.The first is a 7.5kW electric boiler output model, that is suitable for 240V /Single phase electrical supply , and this is designated the FHELN8 , and the largest unit being the 15kW output electric boiler,which is designated the FHELN15 – this model can only be supplied with a three phase , 400 volt supply.These electric boiler for heating and / or hot water via a cylinder lack some of the features of the standard or touch screen series , in that they can use a opentherm plus controller on them ( so not optimised or compensated weather control ) , but they can use a standard room thermostat and you do have the  option to control the output temperature by 0 – 10 Volt signal. Their main advantage is the low acquisition cost or price and these units compliment our range of electric boilers, with a product that is still extremely well built and robust , but at a lower price . As with the rest of the range, they can also produce Domestic Hot Water via a indirect cylinder or calorifier. These boilers feature –

  • An inbuilt energy saving pump ErP compliant heating pump
  • Option to produce domestic hot water via an external indirect cylinder / calorifier and 3-way valve
  • Very quiet operation due to selected switching relays
  • Fluent regulation ( boiler output ) in steps of 2.5 kW for the 7.5kW electric boiler and 5kW steps for the 15kW electric boiler.
  • Minimum output of these electric central heating boilers is  2.5kW  for the 7.5kW model, and 5kW for the 15kW model
  • They have an easy to operate two-digit LED display
  • Option to control the boiler output temperature by a 0 – 10 Volt signal
  • Option to monitor the maximum current drawn to prevent overloading of the consumer board in the building/property – this system reduces the input power to the electric boiler automatically – ensuring that your main fuse does not blow.
  • Again these are electric system boilers and have an inbuilt 7 litre expansion tank

Please note the following for the for the rated current of these electric boilers – The smaller economic electric central heating boilers up to 15kW ,can be wired from either a three phase / 400 volt supply or a single phase 240 volt supply – thus on these units you will see two sets of figures for the maximum rated current – the first number “11” for example on the FHELN8 Model , is the 3 phase Amps – therefore 3 phases , with 11 Amps on each phase. The second figure in the brackets (33) is the single-phase Amps – therefore Single phase / 240 Volt pulling 33 Amps maximum for the FHELN5 Boiler.Where this range differs is that the 15kW electric economic boiler model, can only be used on 3 phase electric.The same applies for the main circuit breaker figures for the boilers – the first figure is if you use 3 phase supply to connect the boiler up , and the bracketed figure i.e. (the number withing here ) is the size require if you use a single phase supply to wire the boiler up.

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A lower cost electric boiler – the Economic Series – from Flexiheat UK – Same quality just a lower price

Economic / Lower cost Series of Electric Boilers Technical Data

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The Economic Series of Electric Boilers – Great product at a great low price or cost – Flexiheat UK

Download the Flexiheat Brochure For Electric Boilers “FHEL” Range

Electric boilers for hot water and central heating

By using your central heating electric boiler in conjunction with a Indirect domestic hot water cylinder or tank, then you can supply plentiful amounts of Domestic Hot Water for your bathing, be it showering or filling a bath and washing up requirements.

This hot water system ensures that the electric central heating boiler not only heats your wet central electric heating system, be it radiators, under floor or a mixture of both and the hot water cylinder via the cylinders internal heating coil.

You can couple up the boiler to an indirect hot water cylinder, that can also have an electric powered immersion heater in it either as a back-up, or to take advantage of cheaper off-peak electricity to heat the domestic hot water over night.

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A diagram showing how an electric central heating boiler is connected to a Domestic Hot Water Cylinder or Hot Water Tank

Using your electric central heating boiler in conjunction with solar hot water heating

An electric boiler can be used as either a “back up” or a “top up” hot water heater for a solar hot water heating system. The boiler can be used to heat up the domestic hot water which is stored in a hot water cylinder, when there is not enough solar energy to get to the desired temperature, which is normally 60 degrees centigrade for stored domestic hot water. This is achieved by using a 3-port valve and a cylinder stat.

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An Electric Boiler can be used to “top up” a solar hot water heating system

Frequently Asked Questions

Are electric central heating boilers expensive to run?

The current electricity cost rate per kWh – (Kilo Watt Hour) is currently 12.376 pence as at 11th August 2019 for the average UK consumer. The average kWh used for heating for low users, which should be considered typically as flats or lower occupancy medium sized houses is around 8,000 kWh per year, thus around £990 per year.

For medium users, which should be though of as a typical 3 bed semi property with the parents and 2 children living there, then this figure is 12,500 kWh per year, which results in a figure of £1,547 per year

Lastly heavy users, which would be a larger property e.g. a 4-bedroom house, parents and 3 teenagers/ young adults, then the consumption figure is 18,00 kWh per year, resulting in a cost per year of £2,228.

NB All prices are quoted ex Vat

Of course, if you are generating your own electricity via solar PV panels, wind turbines, or even water turbines, then these costs can be dramatically reduced, as well as the additional green benefits of adding no CO2 into the environment

Can electric boilers heat radiators?

Yes of course the can- An electric boiler should be thought of as a standard gas or oil boiler, the only difference is that in powered by electricity other than that they work in the same way.

How much does it cost to install an electric boiler?

It should be cheaper than installing a gas boiler, as there is no flue pipe / chimney to install as electric boiler don’t have this requirement. And definitely cheaper than installing an oil boiler, as no oil tank is required as well as the flue/chimney issue. Any competent plumber, who now these days are often qualified in electrical works would easily be able to install the boiler. If they are not qualified in electrical works, then in conjunction with an electrician.

Can you have electric central heating?

Yes- electric central heating in this sense is the same as a conventional wet central heating system but with an electric boiler as the power source, rather than a gas or oil boiler

What size  electric central heating boiler do I require ?

The first part of selecting the correct electric central heating boiler is the central heating load or kW requirement. You can do this in a couple of different ways –

1. Consult a plumber or a heating services engineer –

A good qualified plumber will be able to do a heat loss calculation , but probably won’t have the design insurance indemnities ( which means that they have an insurance policy to claim off – if the system they design / recommend doesn’t work as stated.

If you want a “proper job” as they say you need to consult a CIBSE Heating consultant , who will do all the heat loss calculations etc –

https://www.cibse.org/building-services/find-a-specialist

But they will probably charge you £100 – £150 per hour of design – probably a minimum of £300 – but they do have insurance indemnities- therefore should the heating system not work / or not be adequate enough you have recompense.

2. The cost nothing , but your time method –

Or you could calculate the load yourself using the following website – which is a heat loss calculation app, this will tell you the heat load for each room, input the room data for your property , and them all up – and you end up with your total heating load

https://www.wolseley.co.uk/webapp/wcs/stores/servlet/ProductSelector?catalogId=12001&langId=44&storeId=10203&selectorType=heatloss

Quick note – the result will be in BTU’s – to convert to kW – divide the BTU’S by 3,412 to get the kW figure.

This heat loss calculator is very good an accurate if the information inputted is correct , I’m pretty sure that this ( or very similar) is what plumbers and heating consultants use on a daily basis to do heat loss calculations these days

3.Last but not least the ” Rule of Thumb ” , we don’t recommend using these at all , as they make a lot of assumptions and can be very dangerous ! but here we go – and use at your own risk

For underfloor wet heating systems – use 100 watts per m2 for concrete floors , and for suspended timber floors use 70 watts per m2

For a radiator heating systems – use an average of 1.5kW of output for every radiator. Thus if the central heating system has 10 rads – 10 x 1.5kW = 15kW of heating output is required

One kilowatt of heat will be required for heating every 10 square metres of your property. Thus, for heating a 50 square meters property, you would need a 5 kW electric boiler

We really wouldn’t recommend using these rules of thumb methods, use point 2 at the very least in our opinion, these heat loss calculators are very accurate these days, as long as the information entered is correct

Safety and manufacturing standards 

All of our Electric Central Heating Boilers / Electric Boilers have been tested in accordance with Directives 2006/95/EC (Low Voltage Directive, LVD) and 2004/108/EC (Electromagnetic Compatibility Directive, EMC) and conform to these regulations in full.

These Electric Boilers are also in compliance with the following norms and regulations:
•EN 50110-1:2003 – handling and operation with electrical installations
•EN 55014:2001 – electromagnetic compatibility -conditions for household devices, electrical devices and similar devices
•EN 60 335-1+ed.2:2003 – electrical household devices
•EN 60 335-1+ed.2 zm.A1:2005 – electrical household devices
•EN 61000-3-2 ed.3:2006 – electromagnetic compatibility(EMC) – the limit for the harmonic current emission
•EN 61000-3-3:1997 – electromagnetic compatibility (EMC)–Law on the limitation of voltage fluctuations and flickering of the low-voltage partition network

Electric Boilers in cascade format option

The boiler electronics enable connection of up to 32 boilers into a single intelligent cascade which modulates the performance ranging from minimum output of the first boiler to the total of maximum outputs of all boilers combined. The interconnection of the master and slave boilers is possible only through a system of intelligent modules – i.e. the same interface must be used for master as well as the slave boilers.In this way the largest output that we can do is 32 x 45 kW Boilers, which equates to 1,440 kW of electrical boiler power output.

Electric boilers for sale UK & Ireland

So should you be after an Electric Boiler System, or Electric System Boilers ( We also hear them be referred to an Electric Flow Boiler or even an Electric Water Boiler ) then we at Flexiheat UK are the people to talk to. We think that we have the best range of Electric Central Heating Boilers in the UK and Ireland for both electrically heating a wet heating system  and / or doing your domestic hot water requirements via a hot water cylinder. Should you require anymore assistance or information on our Electric Boilers / Electric Central Heating Boilers , please don’t hesitate to contact our sales team on 01202 822221 or click here for our email contact form