A standard in air conditioning for many years, heat pumps are now also becoming a popular choice for heating. Most rely on HFC refrigerants but in Japan CO2 is popular in systems designed to produce domestic hot water.
A run-away success in Japan, over 4 million of these Eco Cute hot water heat pumps have been sold over the last 10 years.
The use of CO2 heat pumps in northern Europe, however, is still in its infancy due to problems with maintaining heating capacity and efficiency at low ambient temperatures
Mitsubishi Heavy Industries’ Q-ton heat pump appears to have overcome this problem through its use of an innovative two-stage scroll-rotary compressor which provides significantly improved heating capacity at cold outside air temperatures.
A Q-ton was recently successfully installed as part of a project at Colne House, a brand new medical centre in Watford, Hertfordshire, containing two doctors’ surgeries. The Q-ton CO2 heat pump was installed by Stevenage contractor AVC to provide sanitary hot water to 15 consulting rooms and four treatment rooms.
The 3-pipe KX6R VRF system for space heating and cooling comprises four outdoor units supplying 40 indoor fan coils. The system is centrally-controlled by an intelligent touch screen panel for extensive programming for optimal energy efficiency.
Both surgeries are supplied by one 30kW Q-ton model which is connected to a 1,000 litre stainless steel tank with water stored at 75°C. The combined system enables low running cost and carbon reductions.
The Q-ton is capable of generating hot water from 65°C to 90°C from one 30kW Q-ton unit providing 6,000 litres of hot water a day.
Lancaster Hall Hotel
Two 30kW Q-tons have also been installed at the Lancaster Hall Hotel in London.
The hotel consists of two separate boiler rooms with completely segregated hot water and heating systems utilising five boilers running at different pressures in order to cater for up to 250 people.
Mitsubishi Heavy Industries connected two Q-ton to two 2,000 litre hot water storage tanks. The system supplies 12,000 litres per day of domestic hot water at 65°C, saving up to 40% on running costs compared to their existing boiler.