An air source heat pump/ air to water heat pump collects and uses thermal energy from the outside air to heat the home and provide domestic hot water.

Our Daikin air to water Heat Pumps can extract heat from the air even when the outside temperature is as low as -25°C.

The heat generated can be used to warm water for radiators, underfloor heating and your domestic hot water.


You will probably have heard that an Air Source Heat Pump is merely the reverse of a fridge. In essence, this is correct.

Heat Pump works because of a principal called Boyles Law.  This law covers the relationship between temperature, volume and pressure. Basically, any gas when compressed produces heat.  Our Daikin Heat Pumps contain a refrigerant which has a very low boiling point. So when the ambient air is drawn through the outdoor unit and passed over the refrigerant coil the liquid refrigerant starts to boil or, in other words, turns the liquid refrigerant to a gas. This gas is compressed in the compressor creating considerably more heat.  

There are four processes involved in the working of the Heat Pump; Evaporation, Compression, Condensation & Expansion

Evaporation – In a heat exchanger, the liquid refrigerant absorbs energy from the ambient air drawn into the unit by the fan.  The refrigerant then evaporates as it’s temperature rises.

Compression – In a compressor the introduction of electrical energy causes the vaporised but still cool refrigerant to compress and heat up.  The refrigerant leaves the compressor as a hot gas. Boyles law in action.

Condensation – The hot gas flows into the heat exchanger, releases energy to the heating system, condenses and leaves the condenser as hot liquid refrigerant.  This energy heats the hot water for domestic use to the desired temperature.

Expansion – The hot, liquid refrigerant is transferred to the expansion valve where the pressure is reduced very rapidly.  The temperature of the coolant also drops very quickly without releasing energy. The cold, liquid refrigerant is transferred to the evaporator and the cycle begins again.

In essence, the Heat Pump allows us to harness that free energy available in the air and use it to heat your home and domestic hot water.  Because so little electrical energy is needed to run the system this means that 75% of your heating is coming free from the air. As a result of this Daikin air to water heat pumps can offer efficiencies up to 5 times higher than a fossil fuel boiler.  


At Keltic Renewables we are working with the biggest selling heat pump manufacturer in Europe, Daikin.

Daikin are a world leader in Heating Ventilation and Air-Conditioning. They are a core manufacturer and have set the standard on many innovative products that other mananufactuers try to emulate.

Daikin’s world headquarters are in Osaka, Japan where they have a highly regarded reputation for quality, efficiency and environmental awareness. Their pedigree is refrigerants which they manufactuer themselves.

Daikin’s history dates back to the 1920’s when they started manufacturing radiator tubings. From there they saw the potentials of refirgerants and produced their first refrigerator in the 1930s. Daikin produced Japan’s first packaged air conditioning unit in the 1950s with their first packeged heat pump for domestic applications produced in 1958. Since these beginnings they have established themselves as the largest HVAC company in the world with manufacturing facilities across the world.

Daikin’s headquarters in Oostende in Belgium started manufacturing in 1973. They now design and manufacture their products for Europe in their facilities in Belgium, Germany, Czech Republic, Italy and England.


We at Keltic Renewables are trained on Daikins range of products and pride oursleves on providing relevant, no nonsense information and pricing so our clients can make an informed decision that they know will work best for them.


This range of units are our most popular systems.  They provide heating and hot water up to 55 degrees Celsius without the need for back up heater. The heating ouput range are: 4kW, 6kW, 8kW, 11kW, 14kW and 16kW. This heat pump is mounted outside the building where it produces the heat. This heat is transferred into the indoor unit via refrigerant gas lines. The advantage of circulating the heat from heat pump like this is we can gain a higher efficiency and also do not have to worry about water freezing etc if there was a power outage.

The indoor units have different designs to allow our customers different possibilities to suit their interior designs.

Generally, most customers prefer the integrated unit which has a 180 litre or 260 litre factory insulated stainless steel cylinder built in. This allows for huge space savings and a much trimmer installation.

It is possible to have a separate hot water cylinder if required.

We also have the option of installing the Daikin HPSU unit (Heat Pump Solar Unit) which allows for a solar thermal system to be integrated together with the heat pump.  This give a capacity of 300 litre of 500 liter of energy storage. This energy can then be used for both heating and hot water production thus greatly reducing heating bills.

When these systems is in heating mode the unit can vary its flow temperature depending  on outside temperture. This is called weather compensation and is built in as standard across Daikins full range of air to water heat pumps. The advantage of this is that the zone that requires heating does not over heat or under heat via the underfloor heating or low temperature radiators.


This comprises of the high efficiency thermal store which has the Daikin altherma internal components housed above it.  This has the advantage that from one system location the heating, hot water and solar systems can be controlled. The integration of the heat pump and solar storage together has a huge added benefit in that the energy stored can be used for hot water and heating. In other words if there is a bright day and cool evening the system will use some of the stored energy for heating which keeps the heat pump off for longer.

(for more on Daikin solar please click here)


These range of heat pumps were designed for the retrofit market where a higher temperature is required to provide adequate heat via an existing heating system. These units are capable of producing up to 75 degrees Celsius directly from the heat pump without  the need of a back up heater. The units heating output range are: 11kW, 14kW and 16kW.

The indoor unit is floor mounted and can have a 260l capacity hot wtaer tank installed on top to save space.


As Daikin manufacture the majorioty of the components in house and we are a tier 1 agent we can offer a 5 year parts and labour warranty and additional 5 year parts warranty on the compressor, fans and PCB borads on Daikin air to watar heat pumps. This gives our customers  a 10 year piece of mind on the heart and brains of the system.

The only precondition to this is that system will be serviced once a year. We are happy to facilitate this and our existimng customers are happy to see us providing this facility to protect their investment.


How does the heat pump work at below freezing temperatures?

The boiling point of the refrigerants used for air to water heat pumps can be as low as -25 degrees C. This means that once the outside temperature is above this the system can still produce heat.

Is a dual tariff electrical meter beneficial?

Yes it can be but bare in mind that in night time the heat pumps efficiency will reduce as the outside air will be cooler.  If a dual tariff meter is installed other utilities should be managed such as washing mahines, dishwashers etc. to maximise the benefit.

How long should I leave the heat pump running each day?

Generally the internal controls will automate the runtime of the heat pump. As the individual rooms require heat the heat pump will repond accordingly. It is worth noting the heat pump is rarely at 100% ouput. This is because the system when enabled will calculate what the optimum output will be required based on outside temperature (weather compenstaion) and flow and return temperatures.

Do I switch off the heat pump oin th summer or if away on holidays?

Yes you can but we would suggest leave it in standby. This way if there is a sudden prolonged drop in temperature the system will respond even though in standby to prevent freezing etc.

Are the units noisey?

No. The indoor unit contains an a rated circulating pump which is well insulated. The largest outdoor unit has a sound power level of 47 dBa which will not be heard in the house.

How does weather compensation affect domestic hot water?

In short it does not. The system will decide whether to produce heat for heating or hot water. If it is in hot water mode it will bring the tank up to desired temperature in quickest time possible without considering external weather conditions.

How is the heat pump able to reach a higher temperature for domestic hot water without affecting the heating temperature?

The majority of the systems energy will be used for heating. To maximise the efficiency in this mode, weather compensation means the unit will change its flow temperature setpoint depending on outside temperature. Most modern houses do not require a high temperature and if the circulation system is designed properly we will be producing maximum 35 degrees C for underfloor heating  and 45 degrees C for low temperature radiators.

In hot water mode we want to store the water in the cylinder at a higher temperature and the system will use all its energy to do the same.

In other words the two modes are controlled seperatley.


What temperatures should my room be at?

It would be recommended that living rooms would be set at 21, hallways at 19 and bedrooms at 18. However because we provide controls to each main room these csn be altered to suit what you are comfortable with.


Yes, Yes, Yes .

How effective the heat pump will be depends on a number of details:

  • How old is Building?
  • What is the buildings current heat load based on fabric (insulation) losses and ventilation heat losses?
  • What is current heating system?
  • What is current heating circulation system (radiators or underfloor)?
  • How is heating controlled?

The majority of these questions can be answered by way of an energy assessment (BER). We would always advise for thsio to happen for both existing and new builds prior to works beginning.  This will help the end user apply various solutions to there property and quickly get resulting benefits of these changes/upgrades.

The good news is that a property will be entitled to a grant of €3500 for installing a heat pump to replace a boiler starting in April 2018. There will also be further benefits e.g. upgrading controls €700, credit from Electric Ireland of up to €824.80 for also installing a heat pump to replace a boiler.

The full conditions for qualifications of these payments are expected shortly.

Ballylehane, Ballylinan, Co. Laois
(059) 8622017, (085) 8014339

Heat Pumps, Solar Systems, Heat Recovery Ventilation, Underfloor Heating, Plumbing

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