Air conditioning unit uses less refrigerant to challenge traditional chillers

Mitsubishi Electric has launched a new air conditioning unit that uses less refrigerant than traditional VRF (Variable Refrigerant Flow) systems whilst providing simultaneous heating and cooling in a simplified two-pipe design.

The HVRF system operates without using refrigerant in occupied spaces, removing the need for leak detection equipment and allowing more properties to take advantage of manageable phased installation through the system’s modular design.

At the heart of the new system is an HBC (Hybrid Branch Controller) box, which is connected to the outdoor unit via traditional refrigerant piping. Between the HBC box and the indoor fan coils, the system uses water piping but still offers high sensible cooling and stable room temperatures for maximum comfort.

“Many of our buildings have been traditionally cooled and heated through a combination of chiller technology and oil or gas boilers, but with increasing legislation on energy efficiency and the rising cost of fuel, we now need a low-carbon, cost-effective alternative,”

explains Mitsubishi Electric’s Mark Grayston.

“We have developed this new approach to answer the need for energy efficiency and internal comfort.”

Set to rival traditional heating and cooling, the new HVRF system delivers optimum comfort and efficiency, using an innovative combination of unique 2-pipe technology and water to provide simultaneous heating and cooling with heat recovery.

The system is already working to full effect at the offices of mechanical and electrical specialists, Working Environments Ltd, who are using the new air conditioning unit to deliver comfortable and stable internal temperatures for staff at their Southampton headquarters.

“We have worked closely with Mitsubishi Electric for many years and when we first heard of this innovative development, we wanted to be one of the first to check out its merits,”

explained Mike Jenkins, Special Projects Director for Working Environments.

“By combining the benefits of a water based system with the efficiency and flexibility of a heat recovery VRF system, HVRF is proving the ideal integrated solution.”

HVRF has other significant key benefits which open its use up to many other buildings. Having no refrigerant in occupied spaces whilst delivering simultaneous heating and cooling via quiet fan coils means HVRF is particularly suited to applications such as hotels and high end residential situations.

In addition, the system offers significant reductions in installation time and lower running costs and emissions than the traditional methods of heating and cooling.

Current legislation restricts the use of refrigerants in buildings, with EN378 in particular intended to minimise possible hazards to persons, property and the environment from refrigerating systems and refrigerants. As such, leak detection must be provided if, in the case of R410a, a concentration of 0.44 kg/m3refrigerant could be exceeded if all the refrigerant from a system were to leak into a single room.

This legislation is particularly applicable for hotels. Generally, this limits systems to about 20Kg of R410a or forces the addition of leak detection systems. The only other option is to break larger systems down into smaller ones. Either way, an increase in cost and complexity cannot be avoided…until now.

“We realised that one way to reduce cost and minimise possible hazards to persons, property and the environment, would be to remove the refrigerant from occupied spaces using a water based system,”

explained Mark Grayston.

“This hybrid VRF system has been developed exclusively to answer this need.”

The outdoor unit behaves in much the same way as a two-pipe heat recovery VRF system with two refrigerant pipes connecting a Hybrid Branch Controller (HBC), which has been optimised to provide the same efficiency as standard VRF.

The HBC enables simultaneous heating and cooling with heat recovery to take place in a similar way that the standard Branch Controller can. However, instead of two refrigerant pipes sending refrigerant for cooling or heating to the indoor units, hot or cold water is sent instead using either plastic or copper pipe. Efficiency is further improved from the heat-recovery defrost, enabling short defrost times with immediate return to heating.

HVRF provides the function of a four-pipe fan coil system and the efficiency of modern VRF in one system. Off coil temperatures are dependent on on-coil temperatures which results in high sensible cooling and efficient heating. Load capacity control is achieved through the use of inverter driven pumps and flow control valves which are all built into the HBC. Phased installation also reduces building down-time and room sizes can be reduced whilst still providing a high end heating and cooling system.

All the advanced VRF controls can be used and combined with the flexibility of design and installation that VRF offers and high levels of efficiency, HVRF now offers a serious alternative to chiller technology and allows even more building owners to benefit from the low carbon potential of heat pumps.

Further details on the HVRF system is available by calling 01707 282880 or emailing airconditioning(Replace this parenthesis with the @ sign)