Heat only electric boiler range

An electric heat only boiler, which is also known as an electric conventional boiler or regular boiler, was very popular for a central heating system in many UK homes constructed before the early 1990s.

Heat only electric boilers were usually installed as part of an open-vented heating system, which was very popular up until the late 1980s to the early 1990s in the United Kingdom.

Heat-only boilers are best suited for older homes with traditional heating infrastructure, households needing high hot water output via an indirect hot water cylinder, or situations where integration with other heat sources is desired, such as backing up or topping up heat for heat pumps, solid fuel boilers or heat pumps.

Electric boilers emit zero carbon emissions at the source and have a lower carbon footprint compared to fossil fuel boilers.

What is a heat only boiler?

Heat only boilers are also known as open vented, regular or conventional boilers. 

When used in conjunction with an indirect hot water cylinder and a feed and expansion tank (which is located in the loft above the boiler to give and maintain a good amount of head (i.e., pressure) of water to act on the boiler, they heat your central heating requirements, be they radiators or underfloor systems, and domestic hot water demands.

The electric boiler that you’re replacing is probably a heat only boiler if it’s really old. The fact that you will have a separate circulating pump rather than one within the boiler is another indicator that it’s a heat only boiler.

What is an open vent heating system?

An open vent heating system comprises two water tanks, the first being a water storage tank and the second a smaller feed and expansion tank installed in the property’s roof space, relying on gravity to provide the pressure to the wet central heating system.

These tanks also ensure a consistent water level in the heating system, as water is often lost from the hot water system due to evaporation or leaks, and the feed and expansion tank will replace water in the system to keep the pressure constant.

The tank’s height above the electric boiler must meet the minimum operating pressure required by the installed boiler.

They are also usually connected to an indirect hot water storage cylinder (hot water tank) in the airing cupboard that would produce domestic hot water for the property and be fed by the water storage tank in the loft space.

They do not make a combi boiler for an open vented system. If you require an electric combi boiler, then the heating side of the combi boiler must be a sealed heating system i.e. an unvented system – We do a full range of electric combi boilers, which are detailed here – Electric combi boilers

Central heating

Often installed in properties without a gas supply or that didn’t want to use oil as a heating fuel, these electric heating only boilers are an alternative to gas and oil boilers, being energy efficient and easier to install as no flue system is required and no oil tank to locate and install (that an oil boiler would require). The perfect solution, as they have 100% energy efficiency and are cost-effective too!

With the push to reduce reliance on fossil fuels and reduce carbon emissions, the days of the gas boiler or oil boiler seemed to be numbered, and electric boilers, along with heat pumps (most commonly an air source heat pump), which can be powered by electricity from renewable sources such as solar panels or wind turbines, reduce the carbon footprint and reduce electricity costs.

Unlike heat pumps, specifically air source heat pumps, electric boilers have 100% energy efficiency on the immersion heaters all year round. Heat pump efficiency figures drop when the external air temperature drops, when you require heating the most.

Heat loss calculations quantify the energy required to counteract heat loss through the property’s fabric. Please this dedicated webpage for more information on electric boiler sizing.

Heat only boiler

Unlike electric system boilers, which have an integral expansion vessel and inbuilt circulation pump, these direct electric boilers work with heating elements in the form of immersion heaters which heat the warm water in a heat exchanger for the radiators or underfloor home heating system and also generate suitable heat for indirect cylinders to produce domestic hot water.

Most electric boilers, and especially electric heat only boilers, are small in dimensions,with easy boiler installation,are quiet in operation, require less maintenance (thus less maintenance costs) and don’t require an in-depth annual service like their gas boiler counterparts. It is highly recommended to test the RCD on the electrical consumer unit approximately every 4 weeks.

One of the advantages of electric boilers is their simplicity compared to gas and oil boilers. In essence they function as a kettle works, using immersion heaters to heat water for your home heating, be they small or larger homes.

Single-phase versus three-phase electricity supply

Electricity comes in two different supplies – the most common that is often fitted into properties in the UK is a single phase 240 Volt supply. A single phase supply is one cable coming into the electric consumer board in a property. Single phase electricity supplies come in different amp values; standard 2 or 3 bed properties in the UK tend to have a 100 amp electricity supply. Older or smaller properties, such as flats, may only have a 60 amp electric supply.

In short, the number of amps will limit the size of electric boiler you can install; this means that when you have a single phase supply, you can only fit a certain kW output electric boiler.

A three phase supply, on the other hand, has three power cables (or phases) coming into the site.

Heat only direct electric boilers range

The following range of electric boilers can be powered by grid electricity and / or PV Solar generated electricity 

PV ((Photovoltaic) solar panels are a renewable energy source, reducing costs and emissions by powering homes with free, clean energy from the sun, with surplus electricity often fed back to the grid.  

8kW Electric heat only boiler

FHM3-8  The 8kW electric heat only boiler features an outdoor sensor, and an inbuilt circulating pump; is PV solar-ready; with an adjustable output range of 2kW, 4kW, 6kW, and 8kW of heating power output, with options for 230V Single phase or 400V Three phase electricy powered.

This electric boiler modulates to the following heat output steps: 

0.8kW, 0.9kW, 1.3kW, 2kW, 2.6kW, 3.3kW, 4kW, 4.6kW, 5.3kW, 6kW, 6.6kW, 7.3kW, 7.9kW

So yes, this electric central heating system boiler can be set to either 2 kW, 4 kW, 6 kW or 8 kW (technically 7.9kW, but close enough to 8kW for us), and the boiler will ramp up and down the above modulation scale depending on what the central heating system demands and save on heating bills

14kW electric heat-only boiler

The FHM3-14 is a 14 kW electric heat only boiler that includes an outdoor sensor and an inbuilt circulating pump, is PV solar ready, and has an adjustable output range of 6.9 kW, 9.2 kW, 11.5 kW, or 13.8 kW of heating power, operating on 1 phase/230 volts only.

This electric boiler modulates according to the following heat output steps: 

0.8kW, 1.5kW, 2.3kW, 3.5kW, 4.6kW, 5.8kW, 6.9kW, 8.1kW, 9.2kW, 10.4kW, 11.5kW, 12.7kW, 13.8kW 

This electric boiler can be set to either 6.9 kW, 8.1 kW, 9.2 kW or 13.8 kW (technically 13.8 kW but close enough to 14 kW for us), and the boiler will ramp up and down the above modulation scale depending on the central heating system’s demands and save on energy bills.

24kW Electric heat only boiler

FHM3-24: A 24 kW electric heat only boiler with an outdoor sensor and circulating pump that is PV solar-ready, with a 12 kW, 16 kW, 20 kW, or 24 kW adjustable output range – 400 Volt Three Phase electric powered only.

This 24 kW electric boiler modulates to the following heat output steps: 

1kW, 2kW, 4kW, 6kW, 8kW, 10kW, 12kW, 14kW, 16kW, 18kW, 20kW, 22kW, 24kW

This electric boiler can be set to either 12 kW, 16 kW, 20 kW, or 24 kW of heating power, and it will ramp up and down the above modulation scale depending on what the heating system demands.

This boiler range can be used for heating and hot water with an indirect hot water cylinder (storage tank water heater) to produce the DHW. 

This brochure details this above range 

M range electric heating boilers brochure from 2kW to 24kW of output Flexiheat UK 

Manual for this range

M range electric boilers technical and installation manual 2kW to 24kW from Flexiheat UK

Smart phone or tablet app control with Wi-Fi

You can control the “M” series electric boilers using an app on your smartphone or tablet when you have Wi-Fi at the location, which allows you to manage your boiler remotely; for example, you can switch the boiler on when you leave work so that it is warm by the time you get home.

 

Commercial heat only range of electric boilers

From 24 kW onwards we offer our commercial heat only electric boilers. These electric boilers are supplied without an inbuilt pump, as there isn’t enough room to accommodate one within the boiler casing. Thus, one must be installed on the central heating system to overcome the frictional losses of the pipework and fittings.

These electric boiler models have enhanced control capabilities because they can be integrated with building management systems (BMS) for commercial use through our “X” control panel. These units can also be used to produce domestic hot water via indirect cylinders.

Floor mounting kit option for our Thermo Max range

 

This wall or floor mounted electric boiler range is available from 24 kW to 96 kW and is detailed in depth on this webpage : Electric commercial heat only boilers 24kW to 96kW

Gas boiler?

Gas boilers are ever increasing in price with levies place on manufacturers to promote the use sustainable energy or green energy, and using a electric boiler for a wet central heating system is the perfect solution.Electric boilers do not pose a risk of gas leaks, nor do they require a flue for installation.

Contact Flexiheat UK

For more information, support, prices, check stock, purchasing or ordering our cost-effective and energy efficient electric heat only boilers, please don’t hesitate to contact our customer sales team at 01202 822221. Please click here for our email contact form. We serve both trade customers and end users.