Waterford Energy Bureau-Heat Pumps: Waterford County Council

Heat Pumps

A heat pump extracts heat from a low temperature sources (ground, water, and air), upgrades it to a higher temperature where it is used for space and water heating. It operates similar to an air conditioning system, only in reverse. A heat exchanger at the heat source absorbs the low level heat through the evaporation of a refrigerant which is upgraded using a compressor to a high temperature vapour. The high temperature refrigerant vapour then transferred its heat to the buildings central / water heating system. As a compressor is required for the heat pump cycle electricity is needed for it to operate. The efficiency of the cycle is expressed as the ratio useful heat delivered to electrical load of the cycle, called the Coefficient of Performance (COP). So for a system with a COP of 4:1, every kWh of electricity used to drive the cycle returns 4 kWh of heat.

Suitability

There can be several variations / configurations for a heat pump operation, and the type of installation is generally chosen by the suitability to the proposed building being serviced.

Ground and Water Source (Geothermal) Typical COP = 4:1 to 5:1

Lowest possible running costs, as temperatures are relatively constant all year.

There are two main configurations for the external heat exchanger:

Surface collector (horizontal) or Ground Loops. Suited to premises with adequate ground area, or access to water (lake or river). Coils are buried 1-2m below the surface, harnessing direct and indirect solar energy absorbed by the soil or a body of water.
Borehole or vertical Collector. More suitable for smaller plots or areas with restricted space. Geothermal energy is harnessed from the bedrock or from underground water sources such as wells or aquifers.

Air Source (Aerothermal) Typical COP = 3.5:1

This type of heat pump is better suited for retrofitting or where there is a limited space. Heat is absorbed from the air by an external unit located on a roof, ground or fixed to a wall. Unlike water or ground source systems, there will be a greater fluctuation of the air temperature depending on weather conditions, affecting the heat pumps performance.

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Waterford Energy Bureau What We Do Waterfords Energy Requirement Local Energy Projects WEB Projects Energy Efficiency Renewable Energy Wind Energy Solar Energy Heat Pumps Liquid Biofuels Bio Energy CHP Combined Heat and Power Grants Sustainable Transport	Heat Pumps A heat pump extracts heat from a low temperature sources (ground, water, and air), upgrades it to a higher temperature where it is used for space and water heating. It operates similar to an air conditioning system, only in reverse. A heat exchanger at the heat source absorbs the low level heat through the evaporation of a refrigerant which is upgraded using a compressor to a high temperature vapour. The high temperature refrigerant vapour then transferred its heat to the buildings central / water heating system. As a compressor is required for the heat pump cycle electricity is needed for it to operate. The efficiency of the cycle is expressed as the ratio useful heat delivered to electrical load of the cycle, called the Coefficient of Performance (COP). So for a system with a COP of 4:1, every kWh of electricity used to drive the cycle returns 4 kWh of heat. Suitability There can be several variations / configurations for a heat pump operation, and the type of installation is generally chosen by the suitability to the proposed building being serviced. Ground and Water Source (Geothermal) Typical COP = 4:1 to 5:1 Lowest possible running costs, as temperatures are relatively constant all year. There are two main configurations for the external heat exchanger: Surface collector (horizontal) or Ground Loops. Suited to premises with adequate ground area, or access to water (lake or river). Coils are buried 1-2m below the surface, harnessing direct and indirect solar energy absorbed by the soil or a body of water. Borehole or vertical Collector. More suitable for smaller plots or areas with restricted space. Geothermal energy is harnessed from the bedrock or from underground water sources such as wells or aquifers. Air Source (Aerothermal) Typical COP = 3.5:1 This type of heat pump is better suited for retrofitting or where there is a limited space. Heat is absorbed from the air by an external unit located on a roof, ground or fixed to a wall. Unlike water or ground source systems, there will be a greater fluctuation of the air temperature depending on weather conditions, affecting the heat pumps performance.
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