15kW Electric boiler / Electric Boilers

15kw electric boiler ;15kw electric system boiler; electric heating ; home heating

15kW Electric Boiler for a wet central heating system – radiators or underfloor heating.

15kw electric system boiler

Our 15kW electric boiler is our most popular electric boiler, for central heating and hot water system replacement for a gas boiler or oil boiler, as customers look to reduce their carbon footprint / carbon emissions. They can be used for underfloor heating or traditional radiator central heating, or even a combination of both.

These are electric system boilers, so have a pump, pressure relief valve and expansion vessel fitted internally, and these eliminate unnecessary external plumbing and pipework and have a 100% electric energy efficiency.

They can also be used to produce domestic hot water, when used in conjunction with an indirect hot water cylinder, especially if the property has a bath, as you will need an element of domestic hot water storage, as an electric combi boiler will not be able to cope with the demand.

Central heating with green electricity

With gas boilers being phased out in the UK to reduce our reliance on fossil fuels and reduce carbon emissions, electric boilers when powered by carbon neutral or renewable energy sources are just one of the solutions to reducing global warming and help replace gas boilers.

Largest electric boiler on single phase supply?

A 15kw electric boiler is the largest electric boiler you can run off a single phase supply that is commonly connected to properties with a 100 Amp electric supply that we have in the UK.

Thus, at maximum output these 15kw electric boilers can consume 72 Amps – when wired to a single phase / 240-volt supply

Should you put a kettle, a toaster, tumble drier, or hair dryer on, which all can consume 13 Amps each of your single phase / 240 Volt electricity supply – then you can get very close to maximum amps available or even blow you main board fuse.

With the following unique product – Our maximum current Watcher – which essentially, temporarily reduces the boilers output, and thus the amps drawn, should the boiler get close to your maximum amps – all automatically – when the amps drop, the boiler automatically goes back to the power required.

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 to 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 boiler will trip out the main electric board.

Electric Boilers

Electric boilers work without emitting any fumes or waste gases that you get with a gas boiler, which reduces your carbon footprint, eliminates the possibility of a carbon monoxide leak, and allows for flexible installation because a flue system is not required . Electric boilers are almost completely silent when running too thanks to the silent triac power switches. We supply a full range of outputs up to 45kW, so if you require another size, please see our webpage – electric heating boilers 

Wall mounted heating boiler

Advantages at a glance:

Energy saving circulating pump

High efficiency erp smart pumps are used in our 15kw electric boilers, with stainless steel impellers.

Pump protection against clogging

Regular spinning of the pump (once every 24 hours) prevents potential clogging of the pump during an extended electric boiler off period

Very quiet operation

Thanks to the silent triac power switches in this electric heating boiler – they are completely silent.

• Smart electronic modulating system with step less regulation in low power steps or jumps of 2.5 kW each – the modulating electronic control of this wall mounted heating boiler, will ramp up and down the power steps or levels , to suit the central heating system requirements – be it underfloor heating or radiators – this auto heating regulation mode or process ensures reduced energy consumption, as the electric boiler matches the heating output to the demand of the hot water radiators or under floor heating, and result in lower energy bills / running costs.

• Automatic modulating electric boilers (sem system)  – the minimum power of the electric boiler is 2.5 kW, then the boiler modulates up and down the output range in 2.5kW steps .You also have the capabilities of setting the boiler at a maximum kW output i.e., to either 2.5, 5, 7.5, 10, 12.5 or 15kW, and the boiler will ramp up and down depending on the heating system demand to the maximum set value.

• Comes with a wall bracket steel template for wall mounting these electric heating boilers.

Download the Flexiheat Electric Boiler Range Brochure


• Possibility of connecting a controller with “OpenTherm +” communication – these are your “Nest” or “Siri” type of thermostats, that can be wireless or internet thermostats- that you can control from an app on your phone, iPad or computer. Allowing you to control your central heating system.

apple ios virtual; experience dsr solaris; boilers comet electric; experience launch android; launch android virtual; android virtual experience; ios virtual experience; virtual experience dsr; virtual experience launch; mattira electric

Or you can use traditional ambient thermostats,

• Possibility of regulation according to the room or outside temperature

• Possibility of remote control of the electric boiler using an SMS message in conjunction with an SMS module (optional extra)

• Digital control panel with a clear, two-digit LED digital display

• Safety switch protection with heating flow detector

• We use copper elements – not stainless steel shielded elements – as copper has a shorter heat up period, and thus is a better product in this application.

• HDO communication – remote switching of the operation to a low rate by the electricity supplier- very handy if you’re on an economy 7 type of cheaper tariff scheme – saving costs on running your

• Internal heating expansion vessel

• Possibility to control the outlet temperature of the electric boilers by means of a 0 – 10 Volt electric signal

• Possibility of producing hot water in an external storage tank after installing a three-way valve which is controlled by the electric boiler.

• Top design – with all the components to operate a wet central heating system be it underfloor heating systems or radiators, with all pipework connections easily accessed at the bottom of the boiler, for ease of installation. The auto air vent is located at the top of the boiler, to ensure it gets the air removed from these electric boilers and an easy to use digital display inbuilt to the unit.

• Smaller external dimensions of the packaged boiler, with lower water content

• Integrated refill (regulated by hydro block) integrated frost protection

• Small dimensions – you have more location’s to fit you electric heating boiler, with a time saver install, with no additional external plumbing and pipe work are required , as these are sealed system boilers.

• Auto air vent – to remove any air from the electric boilers heat up chamber, and to prevent any damage to the immersion heater / heaters.

• Two year warranty for our insulated steel manufactured boilers.

• No noxious fumes or gases when you use electric central heating boilers.

Electric combi boiler

They simply don’t work at this size , you need a three phase supply for these boilers to give a usable hot water flow rate. See our dedicated webpage on electric combination boilers for more info.

Hot water indirect cylinder heating

domestic hot water heating with an electric boiler;

1. The electric boilers have an automatic system in them that operates both the heating and the indirect DHW cylinder

2. It operates in switching mode

3. Domestic Hot Water always has priority

4. For heating it works at the “heating” temperature – lower temperature (25C to .80°C), can be set and controlled – and you can use weather compensated control –

Compensated weather control- the boiler automatically drops the flow temperature relative to the weather conditions – for example on a day when the temperature is 12C outside – and you want 20C inside, the boiler works out that you only require 50C to the radiators, and this saves you energy and thus running costs.

The boiler then automatically switches on the pump and immersion heater heating elements and regulates to the desired temperature for the heating system.

5. For the DHW cylinder, the electrical boiler heats up to a higher temperature (usually 75-80°C, to heat the DHW indirect stainless steel cylinder as quickly as possible)  – the automatic control closes the heating circuit and opens the DHW storage heater heating circuit, switches on the pump and heating elements and heats to a higher temperature (75-80°C) and heats the DHW cylinder very quickly (100 litres in approx. 10 – 20 minutes! Based on a 15kW )

6. After the DHW Cylinder is heated, it switches to heating (see “4.”)

Why is this indirect set up important?

Because you can have two required temperatures – i.e., the heating side of the boiler, may be running underfloor heating – which needs a maximum temperature of 45C, or if the boiler is compensating the flow temperatures to a radiator system, for example – it may have reduced the flow temperature to 50 or 60C – This would not be a high enough temperature to heat the indirect hot water cylinder

And this is the problem with the old “S” and “Y” plan control system, that use 2 x 2 port valves – one for the heating and one for the DHW indirect water cylinder. You can only have one temperature coming out of the electric boiler – which may well be not high enough to supply the domestic hot water cylinder.

Electric central heating boilers

So call us at Flexiheat UK as we are the electric boiler specialists for the United Kingdom , our helpful friendly and professional sales team are ready to deal with your enquiry, get a price or order please contact our sales team on 01202 822221 or click above on our website for our email contact form.