Fujitsu VRF (variable refrigerant flow) air conditioning systems are the ideal, cost effective solution for the British climate given their ability to simultaneously heat and cool, combined with design flexibility and highly efficient performance.
Welcome to another British summer! The weather and the British obsession with talking about it – often puzzles outsiders until they experience for themselves all four seasons in one week.
Many buildings require both heating and cooling during some part of the year, and there are those that require both at the same time. There are two types of VRF systems. It is important to understand the difference between them. The two types of VRF systems are the 2-pipe, and the 3-pipe or heat recovery type.
About 3-Pipe VRF Systems
With the use of heat recovery, it can move the heat via the refrigerant pipework from the warm to the cold side and save considerable amounts of energy. In an ideal 50/50 cooling/heat scenario, the overall VRF system efficiency (kW power input vs. kW Heat / Cool output) can be as high as 7.6 or 760%.
About 2-Pipe Systems
Two-pipe VRFs, such as the Fujitsu Airstage V-III, can cool or heat, but not both at the same time. These systems are particularly suitable for cooling and heating homes, smaller offices or buildings, or buildings that just need cooling where a heating system already exists.
The design approach for 2 and 3-pipe VRF systems is (should be) completely different. For 2-pipe heat or cooling systems, the outdoor units should serve indoor units that are all on the same side/face of a building or all internal areas.
Each room should also have a similar heat load profile & occupancy levels. Internal/external or north/south areas should never be served by the same outdoor unit because this will result in simultaneous heat/cool demands which a 2-pipe VRF system cannot accommodate.
The only exception to this would be if a 2-pipe VRF system you used for cooling only, in which case the same system can serve internal/external or north/south areas.
Design Approach for 3-pipe Systems
VRF air conditioning systems are inherently efficient, especially the 3-pipe heat recovery variant. However, to achieve maximum efficiency, the VRF system as a whole must be designed to access the potential for heat recovery.
An accurate heat load/loss calculation of the building will reveal the areas that have simultaneous heating and cooling requirements. You see this in the spring and autumn when north facing areas require some heating and south/west & internal areas need some cooling.
Some interior areas can also require cooling in winter when perimeter areas need heating. To maximise heat recovery potential, you should include these areas on the same 3-pipe heat recovery VRF system. In this way, the possibility of heat recovery from a zone to another is maximised.
Different Design Approach with 2-Pipe Systems
Only include rooms with similar heating/cooling loads that occur at the same time & rooms on the same side/orientation of a building should be on the same 2-pipe system. Failure to observe this fundamental requirement for a 2-pipe system will cause temperature control problems and complaints from dissatisfied occupants.
The ideal scenario to achieve maximum energy efficiency in a 3-pipe Heat Recovery VRF system is a 50/50 demand for both cooling & heating at the same time.
VRF systems are very easy to retrofit into existing buildings. Their low running costs, flexibility, the speed of installation and complete control system make them the system of choice for both new and old buildings.
It is far easier and quicker to route relatively small diameter refrigerant pipework around the building than large ducts or water pipes.
Theoretically, there is no building too small for VRF and systems such as the Fujitsu 14kW J-IIS Mini VRF outdoor unit is specifically designed to occupy the smallest possible footprint so that you can site them on balconies, in gardens, on small flat roofs or even on outside walls on suitable brackets.
So, while the general population will continue to debate whether sunglasses, an umbrella, or an overcoat is required, heating and cooling engineers can discuss the most versatile and cost-effective VRF solution for the majority of buildings all year round.