Alternatives to gas boilers
What are the alternatives to gas central heating?
There are already viable alternatives to using gas and oil to heat our homes. In some countries, natural resources have been providing ‘free’ heat for many years. Around nine out of ten homes are heated by Iceland’s hot water springs, for example.
District heating systems
Iceland is a pioneer of so-called ‘district heating’ systems. Through these heating systems, whole streets, developments and even communities are supplied with hot water from a central geothermal plant.
This concept is now being more widely applied across the world. For instance, using low carbon energy sources such as biomass or heat-pumps to recover the waste heat from factories and other industrial activities.
District heating is usually most suitable for campuses or densely populated areas. In short, where lots of people live! But electric heating can provide a more flexible solution for other types of homes…
Electric alternatives to gas boilers can be as basic as bar fires and other portable heaters. More sophisticated systems include modern-day storage heaters and heat-pump systems that provide hot water and underfloor heating.
It’s useful to view electric heating as two separate groups: heaters, and heat-pumps, since they work differently:
Heaters include the kind of electric fires and fan heaters we’re all familiar with – along with more sophisticated devices like storage heaters. This group also includes direct electric underfloor heating, and electric water heating via immersion heaters and electric boilers.
All of these work by using a heating element to heat something up – be it the air, floor, or the water in your tank. Electric heaters are 100% efficient. So they turn virtually all the electricity they use into heat. On the flip side, they use a lot of electricity. And they can be expensive to run if you don’t have Economy 7 or a time of use tariff.
Heat pumps work differently. Instead of generating heat, they simply move it! They work a lot like a fridge going backwards, pumping heat from outside your home into your hot water or heating system.
There are two main types of heat pump. Air source heat pumps (ASHP) – which extract heat from the outside air. And ground-source heat pumps – which (GSHP) take it from pipes laid in the ground. Both have the advantage that they use a lot less power. For a given amount of electricity, Daikin says heat pump systems can be three or four times more efficient heat than an electric heater.
Solar PV (Solar Photovoltaics) is the generation of electricity using energy from the sun. Modern solar panels produce electricity from daylight and do not require direct sunlight, although more electricity is produced on bright, sunny days.
By installing Solar PV panels you can produce free, green energy for your home or business. Solar PV panels are normally mounted on the roof of your building although they can also be placed on the ground when a suitable roof is not available.
A device called an inverter changes the DC electricity produced by the panels into ‘useable’ electricity that can then be used to power appliances in your home or can be fed back into the National Grid.
Solar PV panels contain no moving parts, are low maintenance and only require regular cleaning.
Solar thermal panels use heat from the sun to warm fluid passing through them. This is then used to heat your water, which is stored in a hot water cylinder. An immersion heater/unvented hot water cylinder might be needed as a back-up heater or to get the water to the temperature you want.
There are two main types of solar water heating panels – flat plate and evacuated tubes (referring to the way the water interacts with the panel). Evacuated tubes look like a bank of glass tubes fitted to your roof. Flat plate systems can either be fitted onto the roof or integrated into it. Evacuated tube systems are more efficient than flat-plate versions, so are often smaller but still generate the same amount of hot water. There are also drain-back systems, which drain water from inside the solar panel when the pump is switched off. This prevents water from freezing or boiling inside the solar panel.
Air-source heat pumps can provide fairly low-cost space heating for super insulated homes which are not connected to the gas grid.
Air source heat pumps are a kind of renewable energy technology that take the warmth from the air outside (even when it’s freezing) and use it to heat the home. You can get other heat pumps that do the same thing using the warmth in the ground and in water, but air source heat pumps are suitable for a wider range of properties.
Because the air (or ground, or water) is heated by the sun, the energy that heat pumps produce is still classed as ‘renewable’, even though the pump itself is powered by electricity which may or may not have a renewable source.
There are two types of air source heat pump:
Air-to-water systems heat water which is then circulated around the home via radiators or an underfloor heating system. They can also be used to heat water in a storage tank for the bathroom or kitchen. These heaters produce water at 45-55 degrees C which is much lower than the a gas boiler 75-85 degrees C. If being retrofitted into existing housing stock, it is nearly always the case that the radiators will need to be increased in size to release more heat at the lower temperatures or underfloor heating installed. This will increase the installation costs and can be prohibitive.
Air-to-air systems typically use fans to circulate warm air around the home and cannot be used to heat water.
Cost of electric heating
The upfront cost of low-carbon heating systems can be high. But the good news is that they can be cheaper to run than fossil fuel-powered systems, provided high grade insulation practices are adopted and the space heating is appropriately adapted to cope with the lower temperature output.
Some renewable systems – such as solar hot water heating – can even run for free! (Although they can’t usually provide all of your hot water requirements)
Apart from their high efficiency, all electric heaters have the advantage that they are as green as your electricity supply. So if you sign up to a renewable tariff, your electric heating system effectively generates zero-carbon emissions.