Air Source Heat Pumps (ASHP)
The summer is nearly over and the requirement for air conditioning tends to traditionally fade away as people’s perception of air conditioning systems is that it’s for the summer season and for cooling only. However, this perception is slowly changing as people are starting to realise the benefit of Air Source Heat Pump systems (ASHP).
Heat Pump Air Conditioning Systems can provide comfort all year round providing cooling in summer and heating in winter. Using heat pump air conditioning split systems for individual offices or retail units can provide cooling in summer and heating in winter at much more cost effectively in most cases compared to traditional gas fired heating, such as boilers or electrical heating.
For large commercial applications such as multi-office complexes, sports gyms or hotels the VRV or VRF heat pump air conditioning system would provide ideal cooling in summer and heating in winter at very good running costs and initial installation may work out cheaper as well compared to traditional heating systems that would be considered at the time.
Air source heat pumps are a renewable energy technology that take warmth from the air outside (even when it’s freezing) and use it to heat internal space such as offices or retail units, air source heat pumps are suitable for a wider range of properties.
How does the Air Conditioning Heat Pump System work?
Air source heat pumps use the same type of technology that keeps your fridge cold, but in reverse. A liquid refrigerant that has a very low boiling point is pumped on a loop between two heat exchangers. This refrigerant takes on heat energy from the outside ambient air temperature and turns into a gas as it warms up. This gas is then compressed back into a liquid, which increases its temperature further. The warm refrigerant then goes through a heat exchanger, which transfers the warmth to a separate body of air circulating around a room or water for circulating round the central heating system. During the final stage the liquid refrigerant goes through an expansion valve reducing the pressure and temperature and the cycle repeats.
Coefficient of Performance or COP is why heat pumps are a useful technology: if you put 1kWh of energy into a system you will get more than 1kWh of heat energy out. Typically a heat pump has a maximum CoP of 2 or 3, meaning for 1kWh of electricity you will get 2 or 3 kWh’s of heat, in some cases it can be even more.
Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV), is an HVAC technology invented by Daikin Industries. The alternative system supplied by other manufacturers is the Variable Refrigerant Flow (VRF) system.
These VRV / VRF refrigerant heat pump air conditioning systems can supply cooling and heating in large quantities using single or multiple condensing units (which may be located outdoors or indoors, water or air cooled) and is circulate the cooling and heating within a building to multiple indoor units in multiple areas / offices. VRV or VRF systems, unlike conventional chiller or LPHW -based systems, allow for varying degrees of cooling or heating in only certain areas, reducing energy consumption.
VRV & VRFs are typically installed with an air conditioner inverter which adds a DC inverter to the compressor in order to support variable motor speed and thus variable refrigerant volume or variable refrigerant flow rather than simply perform on/off operation. By operating at varying speeds, VRV & VRF units work only at the needed rate allowing for substantial energy savings at load conditions.
Heat recovery VRV & VRF technology allows individual indoor units to heat or cool as required, while the compressor load benefits from the internal heat recovery. Energy savings of up to 55% are predicted over comparable unitary equipment. This also results in greater control of the building’s interior temperature by the building’s occupants.
VRV & VRF systems come in two system formats, two pipe and three pipe systems. In a heat pump two pipe system all of the zones must either be all in cooling or all in heating. Heat Recovery (HR) systems have the ability to simultaneously heat certain zones while cooling others; this is usually done through a three pipe design, with the exception of some brands, whose systems are able to do this with a two pipe system using a branch circuit (BC) controller to the individual indoor evaporator zones. In this case the heat extracted from zones requiring cooling is put to use in the zones requiring heating. This is made possible because the heating unit is functioning as a condenser, providing sub-cooled liquid back into the line that is being used for cooling. While the heat recovery system has a greater initial cost, it allows for better zoned thermal control of a building and overall greater efficiencies.
In heat recovery VRV & VRF systems, some of the indoor units may be in cooling mode while others are in heating mode, reducing energy consumption. If the coefficient of performance in cooling mode of a system is 3, and the coefficient of performance in heating mode is 4, then heat recovery performance can reach more than 7. While it is unlikely that this balance of cooling and heating demand will happen often throughout the year, energy efficiency can be greatly improved when the scenario occurs.
VRV & VRF systems may be air or water cooled. If air cooled, VRV & VRF condensing units are exposed to outside air and may be outdoors, and condensing units are the size of large refrigerators, since they need to contain a large condenser (heat exchanger) to transfer heat to the surrounding air, because air doesn’t have a high heat capacity. If water cooled, the condensing units are placed indoors and are much smaller and cooled, using water, possibly by a cooling tower.
Chillaire Limited can design, supply and install air source heat pump air conditioning systems for individual areas, offices or retails units using wall mounted, ceiling mounted our ducted indoor fan coil units.
We also supply Variable Refrigerant Volume (VRV or Variable Refrigerant Flow (VRF) systems for large buildings or multi office / area or complex to provide cooling and heating to individual areas at the same time with energy saving costs.
Call Chillaire Limited today to assist you with your Air Source Heat Pump Split System or VRV or VRF Air Source Heat Pump multi system. From initial site survey, design, supply, installation, warranty and future planned maintenance with 24 hour service.
We have offices throughout central England: