Heat only electric boiler range

An electric heat-only boiler, which is also known as an electric conventional boiler or electric 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 in the United Kingdom until the late 1980s and early 1990s.

Heat-only boilers are best suited for older homes with traditional central heating infrastructure (radiators or underfloor heating) and 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 produce instant hot water, 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 is to be located and installed (that an oil boiler would require). They are the perfect solution, with 100% energy efficiency and cost-effectiveness!

With the push to reduce reliance on fossil fuels and reduce carbon emissions, the days of the gas boiler or oil boiler seem 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 visit 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, especially electric heat-only boilers, are small in dimensions, with easy boiler installation; are quiet in operation; require less maintenance (thus lower 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 work like a kettle, using immersion heaters to heat water for your home heating, whether in small or larger homes.

Single-phase versus three-phase electricity supply

Electricity comes in two different supplies, with the most common, often fitted in properties in the UK, being a single-phase 240-volt supply. A single-phase supply consists of a single cable that connects to 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 limits the size of the electric boiler you can install; this restriction means that with a single-phase supply, you can only fit an electric boiler with a certain kW output.

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 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.  

Electric heat-only boiler range

With a full range from as low as 4.5 kW all the way up to 96 kW, we have the electric heat-only boiler to suit all needs.

Here is a brief overall detail of the boilers. 

Controller options for the 4.5 kW to 24 kW range of heat-only boilers 

From 4.5 to 24 kW, the control panel comes in two options 

“O” control panel – This panel option comes with heating optimisation and weather compensation – you need an external temperature sensor, which we can supply

or 

“V” control panel – This panel option comes with heating optimisation and weather compensation (you need an external temperature sensor, which we can supply), and also the ability to produce domestic hot water via an indirect hot water cylinder (an indirect storage tank for water heating); again, an immersion sensor is required for this DHW capability, which we can supply.

Manual for this range from 4.5 kW to 24 kW

Electric boilers technical and installation manual 4.5kW to 24kW from Flexiheat UK

Commercial heat only range of electric boilers

From 28 kW onwards, we offer our commercial heat-only electric boilers with the “X” control panel. This control panel (“X” control panel), which is integral to our electric boilers, is fully Modbus-compatible and includes the following features:

• Frost protection system – if the water temperature drops below 7°C, the boiler automatically raises it above 7°C to prevent freezing.

• Inputs:

• Two temperature sensor connections – one for connecting an external temperature sensor for weather compensation and the other for an immersion sensor for control and production of sanitary-grade hot water via an indirect commercial hot water cylinder. Both of these optional sensors are available from us.
• Remote On/Off signal
• Safety thermostats switch off.
• 0-10 volt analogue signal for set point temp or percentage of power output
• Outputs: 
• 0-10 volt temperature signal or percentage of power (power steps)
• Error signal

Thermo Extra commercial electric hot water boilers, with outputs ranging from 28 kW to 96 kW, are available from Flexiheat UK.

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 also 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 placed on manufacturers to promote the use of sustainable energy or green energy, and using an 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.