A heat pump is just like a refrigerator at home working in reverse. The refrigerant in the system absorbs low-grade heat from the air outside like a sponge. The compressor in the system squeezes the heat out of the refrigerant increasing the temperature as it does so. This heat is used to heat the water circulating around your radiators.

Samsung EHS is a split type system comprising an indoor boiler connected to an outdoor unit; these are connected together with 2 refrigerant pipes installed on site

Heat pump systems are not radically different from a conventional system. They still utilise the same hot water pipe work and radiators or under floor heating system. The boiler is replaced with a hydro box, this device looks like a boiler and carries out same functions, the difference is that instead of burning fossil fuel to heat the water, this system uses a heat pump to absorb heat from the air outside and pump it into the water in the house

Heat pumps contain a refrigerant gas which is capable of absorbing heat even in very low temperatures, just like a sponge absorbs water. Using a pump (compressor) we squeeze this heat out of the refrigerant and into the water. The harder we squeeze (compress) the gas the higher the temperature available.

Some air source heat pumps can cool as well as heat. However caution should be applied when cooling with these machines, if we cool the water in the system any exposed metal components will sweat. Typically you cannot use radiators or under floor coils for cooling. Fan coil units are the best option if this is to be done effectively. Samsung EHS is the only system available which can also have air conditioning units installed which can cool or heat independently of the rest of the system.

A typical air source heat pump is silent in operation inside the house; the boiler is much quieter than a conventional fossil fuel boiler. The unit outside emits 60dBa when running flat out. This is equivalent to the noise of a typical conversation with someone 1m away. In most cases there are no problems with using this technology in high density housing applications.

Air source heat pumps have a life expectancy of 15 years in normal applications if maintained correctly.

Yes our systems are now classed as a renewable technology.

In most cases yes, a survey would normally be carried out to check equipment sightings, power supply requirements and suitability of existing radiators to confirm suitability.

The controls on these systems have many options not unlike all electronic equipment available today. In most cases these are set up and never adjusted again after commissioning. The day to day operation of the systems is generally simple, control is by a room thermostat and radiator valves just like a conventional system, any advanced settings are usually adjusted at maintenance.

The outdoor unit (absorber) is essentially the same as an air-conditioning unit out door unit. These have been used for the last 30 years and have a proven track record if installed and maintained correctly. The maintenance involved is essentially making sure the coils are clean and free from any obstructions.

In any heating system the lower the circulating water temperature the better the efficiency. Under floor usually operates with a water temperature of 45C, radiators operate at 55C with a heat pump and 70C with a fossil fuel boiler. Using radiators on a heat pump is the norm but in some cases radiators will need resizing to suit the lower water temperatures from the HP. We can calculate this for you.

A typical house needs a 9kW heating system, assuming a COP of 3 means the electrical energy input required would be 3kW. If you have wind or PV electricity available it can of course contribute towards this load but connecting one to the other with no help from the mains supply is not practical as supply and demand will vary unpredictably. It is possible to run the system 100% from wind power and solar PV if there is enough energy available

The unit needs to be installed 150mm above the ground on an external wall of the building. It is essential that the unit gets enough air to breath so enclosing it will reduce efficiency. Blocking airflow with wheelie bins or plants is not a good idea. Enclosures re available and sight screens can be used. Most systems need to be installed less than 30 metres away from the boiler.

The energy the heat pump absorbs is free as it is all around us, the only work it has to do is to pump it from outside to inside, hence the name heat – pump. This process is very energy efficient, it takes approximately 300 Watts of energy to move 1000 Watts of energy into your house so for each 1kW of electricity consumed between 3kW – 5kW of heat energy can be absorbed and transferred. By contrast, conventional fossil fuel boilers produce less heat output, about 0.85kW for every kW consumed, therefore heat pumps are, eco-friendly using renewable energy reducing CO2 emissions.

The maintenance schedule for an air source heat pump is a little more complicated than a conventional gas boiler. You need to allow up to £250+ vat for an annual ser ice visit and up to 2 call outs for a system serving a typical 3 bedroom house. A similar service agreement for a gas boiler will be £156/ year

Air source units can deliver sanitary hot water at up to 55C even in ambient temperatures of -20C. These systems are very popular in Scandinavia where the weather is much colder than in the UK. The efficiency of the heat pump will fall as the ambient temperature falls; this is discussed in another question.

The installed cost of an air source heat pump is typically 50-100% higher than a gas boiler. Oil and LPG boiler installations are approximately the same as a heat pump installation.

Payback periods depend on your annual energy usage. If your usage is high payback is faster than low usage properties. We can calculate this for you if you have old bills showing usage over the past 12 months.

In some cases the prediction of run cost have been wide of the mark, when calculating this energy use assumptions about usage have to be made especially in new build projects. If accurate energy use figures or copies of energy bills are available the accuracy of these predictions is very good. Like all software, if bad information is put in bad figures come out.

Manufacturers tend to give an energy efficiency figure for their kit at one "nominal" condition, typically 6 degree outdoors temperature and 20 degree indoor temperature. They are required to do this as part of EN14511. Generally this figure is a good indication of the sort of efficiencies you could expect over a whole year. Bizarrely there is no approved calculation method for working out whole year efficiencies so proceed with caution if figures vary from the nominal figures.

Air source heat pumps are designed to operate efficiently in ambient of as low as -20C, even at these temperatures the COP is over 2.

The cop of heat pumps is inversely proportional to the difference between the temperature of the heat source (the air or the ground) and the temperature of the water circulating round the building. If the difference is high the cop falls and visa versa. So in warm weather the COP is high and in cold it falls. See graph below. Note that reducing the circulating water temperature increases COP.