Increasing energy bills, the need to reduce carbon emissions and the ever changing government legislation are driving the demand for alternative forms of domestic heating to improve energy efficiency.
Many people have heard of ground source heat pumps and the high efficiency levels they can offer but few people have realized that air source heat pumps can also offer higher levels of efficiency* when compared to more traditional methods of heating our homes.
Air source heat pumps are much easier to install than ground source, and require no major ground works or hole boring, this means they are suitable for nearly all types of dwellings.
The Mitsubishi Electric Ecodan range of air source heat pump systems have been developed specifically for the UK climate and bring advanced, inverter-driven technology originally developed for the commercial heating sector, With a UK-built cylinder and self-learning controls optimized to provide all the heating and hot water a home needs, whatever the weather.
The Ecodan air source heat pump system consists of an external heat pump unit which is fitted outside in the ambient air. It harvests renewable, low grade energy from the outdoor air and upgrades this into useful heat to supply a home with hot water and heating. For every 1kW of electricity fed into an Ecodan you could get at least 3kW of heating energy. The overall system efficiency and energy savings will depend on each individual property, system design and installation, and operational settings.
The Ecodan heat pump unit can work all year round even if the outdoor temperature should drop as low as -25°C (for some models)
The technology inside the air source heat pump is similar to any domestic refrigerator, which uses a vapour compression cycle. The main components in the air source heat pump are the compressor, the expansion valve and two heat exchangers (an evaporator and a condenser).
1. Refrigerant in the evaporator is colder than the heat source. This causes the heat to move from the heat source (in this case the outside ambient air) to the refrigerant, which then evaporates.
2. This vapour moves to the compressor and reaches a higher temperatures and pressures.
3. The hot vapour now enters the condenser and gives off heat as it condenses.
4. The refrigerant then moves to the expansion valve; drops in temperature and pressure; and then returns to the evaporator.
Energy savings of over 30% can be achieved by using a heat pump with a variable flow temperature as opposed to a fixed flow temperature. When installing a heat pump with a fixed flow temperature of 45°C, annual running costs for a three bedroom house are comparable to a traditional gas boiler. If variable flow temperature with radiators are used, the running cost savings are over 20% and even greater for under floor heating systems.
In using lower flow temperatures a more consistent heat output is achieved, Ecodan therefore gives a greater level of comfort, lower CO2 emissions and more efficient operation which reduces its running costs when heating the home.
This is an alternative to high temperature radiators that operate with sporadic bursts of heat in a bid to maintain the desired room temperature. Homes with suitably sized radiators can now enjoy a constant, controlled living environment, whilst benefiting from reduced system running costs and lessening the impact on our environment.
Capacity control in standard radiator systems, with a fixed flow temperature is controlled by Thermostatic Radiator Valves. These operate by turning the radiators on and off to maintain the desired temperature. For example at 2°C, with 45°C flow temperature, the radiators will be on 50% of the time and off for the other 50% of the time. The Ecodan will vary the flow temperature automatically, based on the ambient temperature to keep the house warm and comfortable. Operating at these lower flow temperatures can significantly improve the overall system efficiency.
Ecodan air source heat pumps are ideal for use in a variety of house sizes or styles and its carefully developed control system is designed to work perfectly to provide hot water to either traditional radiators or under floor heating systems.
Traditionally heat pumps have been seen as only suitable for under floor heating, however with the advanced control system of Ecodan and its ability to provide optimum variable flow temperature control, radiators can now be easily provided with the hot water they need and prove to be a very efficient option.
At the heart of every Ecodan unit is a modern, inverter-driven heat pump compressor which converts free energy from the air and upgrades it to higher temperatures suitable for heating. The inverter control regulates the system so that heat output modulates to match the exact capacity required, meaning the boiler will only consume the exact energy needed at any given time and thus increase efficiency further.
What are the benefits of the Ecodan
* Assuming the design flow temperature is 35°C maximum
** Based on a 5kW model
For every 1kW of input electrical energy, Ecodan harvests and upgrades renewable heat from the outdoor air to provide the home with an average of at least 3kW of heat output