Heatpump Information

What are heatpumps?

A heatpump is an electrical device that extracts energy (or heat) from the ground or the air – and converts in into hot water for domestic heating bathing purposes. It typically replaces an oil or gas boiler in a building and operates for ca. 40% – 50% of the cost of a fossil fuel boiler. They operate most efficiently in moderate Climates (like Ireland). Heatpumps are effectively refridgerators or air-conditioning systems in reverse and have been manufactured for over 6 decades.

All domestically required energy (either electricity or heat) can be measured in kWH units or kilowatt Hour units. Danfoss heatpumps in this country output 4 – 5 kWH units of heat for every 1 kWH unit of electricity they consume. This makes them the most efficient heating system available today.

In most mainland European countries today – newly constructed dwellings would rarely use a fossil fuel heating system, opting for renewable systems like heatpumps for heating and hot water.

Main benefits of Heatpumps

  • They offer huge savings on heating and hot water bills
  • There are no Fossil Fuels (Oil, Gas…) needed for heating
  • They are eco-friendly and reduce the carbon footprint of any building
  • They improve the energy rating (BER) of a building increasing its value
  • They can run in weather compensating mode which means they automatically adjust to the outside temperature
  • They are low maintenance and require minimal servicing
  • They are safe to install inside a building – this minimising heat-loss from hot water pipes
  • They are particularly suited to underfloor heating systems

How do Heatpumps Work?

  1. Brine* circulates in a collector coil and absorbs the heat energy from bedrock, ground, air or water.
  2. At the heat exchanger (evaporator) the tepid brine in the collector coil meets the ice-cold refrigerant** in the heat pump, which is then heated a few degrees and evaporates.
  3. Then, a compressor compresses the refrigerant. The heat that is then generated is transferred via a heat exchanger (condenser) to the house's heating system.
  4. The refrigerant circulates and an expansion valve lowers the pressure and the refrigerant becomes cold again. The process begins again when the refrigerant meets the tepid brine from the collector coil.

* The brine is a mixture that cannot freeze, for example alcohol or glycol.
** Modern environmentally sound refrigerant are used, e.g. hydrocarbons and carbon dioxide. Formerly, freon was used.


Cost Savings Geothermal Heatpump Vs Oil Boiler

The Heating load or requirement in any particular dwelling or residential building remains the same regardless of which type of heat source it has. In quantifiable terms this is usually calculated as follows:

The size or square meterage of the building times the heat-loss or heating load per sqM (making certain allowances for the climate and the indoor temperature required). Heat-loss is governed typically by the insulation levels in the building.
Heat Energy, like electrical energy can be measured in kWh units (kilowatt hour units). ESB Bills or Bord Gais Bills for example are measured in kWh units times a cost per unit in cents. Although Oil bills are still in litres – it is easy to convert from litres of oil to kWh units – as per this UK Carbon Trust Link: http://www.carbontrust.co.uk/resource/energy_units/default.htm

Let’s take a new-build 250sqM dwelling constructed to the current building regulations: It will lose ca. 40w of heat per sqM during the coldest period of the winter. In other words 250sqM x 40w = 10,000w – 10kW. This means that it requires 10 kW of heat to keep the building at a constant temperature. Every hour it will require 10kWH units. Over the course of a year the house may require 2500 hours of heat meaning that the total annual heat consumption for this house will be 25,000kWH units
The cost of providing this amount of heat using is as follows:

  1. Oil Boiler
    • 1 Litre of Home Heating Oil = 11kWh units
    • 1 Litre of home heating oil =  €0.75 (average inc VAT over last 12 months)
    • 1 kWh unit of heating energy supplied in oil costs  €0.068
    • Oil cost for above house = 25,000 x 6.8cents = €1,700.00 / annum
  1. Heatpump
    • ESB Day Rate for domestic is currently €0.15  / kWh unit
    • Night Saver Rate is €0.08 / kWh unit   (11:00pm – 8:00am Winter / 12:00am – 9:00am Summer)
    • Heatpump will run  60% day rate / 40% night rate
    • Average kWh unit cost of €0.13
    • Danfoss Geothermal Heatpump has a COP (Coefficient of Performance) of at worst 4 (but this is typically 5 in the Irish climate) i.e. 1 ESB kWh unit consumed – 4kWh units of heat outputted
    • 25,000 kWh units of heat requires 6,250 kWh units of energy to run the heatpump
    • Heatpump cost for house = 6,250 x 13c = €812.50

In other words to warm the house with 25,000 kWh units of heat:
- Oil = 6.8c/unit
- Heatpump = 3.25c/unit

- Thus Heatpumps will heat at less than 50% of the cost Oil (currently).

Energy sources for heatpumps

There are five different types of heat source


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