Heat Pumps

Heat Pumps

Heat Pumps draw heat from the environment using the conventional refrigeration cycle to produce more energy than they consume. They are an extremely effective and efficient way to not only heat your home but produce all your hot water.

Daly work with a number of suppliers, including Ecoforest, Dimplex and Hitachi so that we can design and install renewable energy systems that best suits your needs.

There are 3 types of heat pumps conventionally used in the UK and Ireland. The source you choose largely depends on your specific circumstances.

  • Ground Source Heat Pumps
  • Air Source Heat Pumps
  • Water to Water Heat Pumps (less common)

Ground Source Heat Pumps

Ground Source Heat Pump Systems rely on the energy absorbed from the sun and rainwater penetration to keep the ground re-energised, which in the UK and Ireland results in a fairly constant temperature of about 8-12°C. This energy is absorbed by a series of HDPE plastic pipes which collect the energy via a water/ antifreeze solution commonly referred to as “brine”. The technology itself is well proven and has improved dramatically in the last 5 years. 80% of homes in Sweden have heat pumps as their heating system. At Daly we choose to work with Ecoforest as they are a company that are at the forefront of this cutting edge technology. Their heat pump is a compact unit which has the pumps, expansion vessels etc all built into the unit. It also uses Inverter Compressor Technology which modulates the heat output and comes in 2 sizes in the domestic range: 3-12kw and 5-22kw, both available in single or three phase. They also boast a unit which has an integrated 170L domestic hot water cylinder and with it’s built in HTR technology can produce hot water up to 70°C at no extra cost. It does this by using a second small heat exchanger which takes the excess heat from the refrigerant cycle and “tops-up” the hot water when on heating mode, resulting in hot water being produced when the system is on heating the Underfloor Heating or Rads at no additional cost to the home owner. This heat pump is also very quiet in operation and is therefore designed to be fitted inside the property, typically in a ground floor store, cloak room or Utility room.

Ecoforest B1 GSHP
Ecoforest B1 GSHP

The first consideration is in choosing a ground source heat pump are site specific and include:

  • The building’s energy characteristics and requirements. A heat pump is an ideal system for a low energy dwelling such where the typical heat load is less than 40 W/m2. A typical system in the Winter should be operating for a maximum period of 12 hours over a 24 hour period.
  • Location and Topography of Site
  • Geology of the ground - ground source heat pumps operate through pipes most commonly laid horizontally in trenches dug 1.2 metres deep. They can also operate from pipe laid in a bore hole, but this option is more expensive and would only be chosen where there was not enough ground available to lay horizontally. A typical horizontal collector system requires an approximate area of 400 – 800 m2 depending on the size of house.
Geothermal Pipework for GSHP
Geothermal Pipework for GSHP

Water to Water Heat Pumps

Water Source Heat Pumps work in a similar fashion but are less common as they require you to be not only near a suitable body of water and requires the permission of the water management agency. They work using similar technology as the ground source heat pumps, but an external pump is required and it is recommended to use a titanium plate heat exchanger if the water is found to be hard. At Daly we would argue that a well designed and installed conventional GSHP system is as effective as a water to water system as the additional COP gained by extracting water at 10-15°C can often be offset by the electrical energy to run an additional circulating pump (depending on local water conditions).

Air Source Heat Pumps

Air Source Heat Pumps work using similar technology as the ground source heat pumps, but using the outside air as its energy source. In the UK and Ireland, the outside air temperature rarely goes below -3°C. The heat or energy moves from hot to cold (2nd law of thermodynamics) and the refrigerant in the heat pump boils at very low temperatures of -30°C so the difference between the outside air and refrigerant create the energy that flows into the heat pump.

Having installed heat pumps since 2007, we have built up significant experience in the installation of heat pump technology.
With having installed GSHP & ASHP System in similar sized houses with similar insulation specifications, we have found after going back to review our systems that a typical ASHP will have a 15-20% higher running cost than GSHPSystems. This is still significantly better than a fossil fuel system as an ASHP will still be around 400% efficient compared to an oil or gas boiler which is around 90% efficient. ASHP Systems are cheaper to install than a GSHP System with the main difference being that the unit will have to be mounted at the side of your property or garage whereas the GSHP unit is internal in the house.
An Air Source Heat Pump uses a fan to draw the outside air across the evaporator and during the Winter season will have to carry out periodic defrosts as the evaporator will begin to form a layer of ice as the heat is drawn out of the air. The defrost process requires a 4-way valve inside the unit to switch the operation of the refrigerant system and draw energy back from the heating system to carry out the defrost. A typical defrost can take 3 to 6 minutes to complete.

Hitachi Yutaki ASHP
Hitachi Yutaki ASHP

Maintenance Requirements

The maintenance requirements for both systems are minimal. There are filters on both systems which can be removed and cleaned and after this is done at commissioning stage it should not have to be done on a repeated basis. Other external factors such as ensuring the pressure in the heating and/ or brine circuits is regularly checked and the quality of the water will have an impact on the performance and longevity of these systems but this is no different to a conventional heating system.

Contact us for more information on Heat Pumps.

Cost Considerations

Ground Source

Ground Source Heat Pumps are more expensive to install than Air Source Heat Pumps, but are more efficient and have a lifespan of 20-25 years.

Air Source Heat Pumps

Air Source Heat Pumps are becoming more popular in the UK and Ireland as they are significantly less expensive to install. This is because they don’t require any ground works and need less space, which also makes them an excellent choice for urban dwellings, flats and apartments.

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