This video shows how the Polar Energi multi system indoor unit extracts maximum energy from Panasonic’s range of outdoor heat pumps.


Heat Exchanger

Traditionally, air to water heating systems have used a plate type heat exchanger. Polar Energi tanks use a heating coil providing effective heat transfer within the water tank. Heating capacity is not reduced by factors which affect flow such as sludge in the heating system.

Patented coil design

Regulations require that refrigerant gas pipe is contained within another pipe in the water tank. In the event of a pipe failure this ensures refrigerant gas can be vented off safely without coming into contact with the water supply. The requirement for this can cause a massive reduction in heat transfer efficiency. Polar Energi have eliminated this problem by developing a patented design of “pipe within a pipe”. This gives a gap of 0.1mm, maintaining safety, while allowing over 90% contact between the inner and outer heating coils.


 All heat pumps create “superheat” in the compressor which is lost in most heat pump systems. Polar Energi have created a way of harnessing this heat energy and transferring it into the hot water system through a patented heat store collar. This increases the temperature of hot water from the 55 degrees C produced by refrigerant gas, bringing it within 80 degrees C for domestic hot water. 

Preheating of DHW

Water for the domestic hot water supply is initially fed through a heat exchange coil in the central heating system section of a multi tank. This preheats the water so when it reaches the domestic hot water tank and heat exchanger, maximum heating of the water is obtained. 

Defrost cycle

When air temperatures drop near zero, frosting occurs on the outdoor unit. To combat this, all heat pumps will introduce a reverse cycle to defrost the system. This can occur every 40 minutes and in most systems lasts over 6 minutes. After initially starting, heat is drawn from the hot water in the tank to continue the cycle.  Electric heaters are then required to maintain temperature in the hot water. The defrost cycle in a Polar Energi tank lasts only 45 seconds due to the higher tank temperature and design of the system. Heat is also transferred from the patented heat store collar, preventing the water temperature being affected. When a heat pump is in defrost mode, it still consumes power, but cannot perform its primary function of heating water. The time spent in defrost mode over a 24 hour period means Polar Energi tanks spend approx 3 hours less in this state than our competitors.

High COP


Because of efficiencies in the design of Polar Energi tanks, they have a higher Coeffient of Performance (COP) than our competitors. This assists architects and consultant engineers produce efficient buildings, availing of incentive schemes where available.

Until recently, COP figures were calculated without including the defrost cycle, which in colder ambient temperatures has a major impact on running costs. In addition, manufacturers could choose the ambient temperature at which this was tested. Polar Energi products previously used an ambient temp of 12°c and this gave a COP figure of 8.43 on the VP150/170L multi tank. New regulations introduced in 2019 stipulate COP figures should be standardised and include the defrost cycle. This has reduced the figures for all manufacturers, however, some figures are still being quoted using the old system. When comparing efficiencies of Polar Energi products with those of other manufacturers, ensure you are comparing “like for like”. Details are printed on the specification sheets on this website, but contact us if you have any queries.

High COP means more than just good figures on a page, it means real savings in annual running costs.


Any tank for hot water must incorporate a system to eliminate Legionella. In most heat pump systems, electric heaters will be programmed to periodically increase the water temperature to kill any traces of Legionella in the tank. These heaters use electric power, increasing running costs and reducing efficiency. 

Because Polar Energi tanks achieve a water temperature of within 80 degrees C from the superheating process, the water is already hot enough to prevent Legionella in the tank and the need for additional heating and therefore electricity consumption, is minimal.

Find out more about the range of products from Polar Energi