Our policy at Total Floor heating is always to provide the very best quality equipment at the best possible price and provide the most efficient way to interlink the equipment into the heating/hot water system. This policy is very important with Heat Pump technology as efficiency is improved when the Heat pump is to a high technical standard. Another very important factor in improving efficiency is to reduce as much as possible the temperature lift i.e. the difference between the temperature of the heat source and the output temperature of the heat pump. As underfloor heating works at low water temperatures the temperature lift is reduced therefore the efficiency is improved. With ground source heat pumps the design of the collector loop is very important. The diagram below shows the COP ( coefficient of performance ) for an ideal heat pump as a function of temperature lift, where the temperature of the heat source is zero degree Celsius . Also shown is the range of actual COPs for various types and sizes of heat pumps at different temperature lifts.
If a heat pump has a COP of 5 that means you get 5 units of heat energy for 1 unit of electric energy.
Click graph to enlarge
Heat pumps offer the most energy-efficient way to provide heating and cooling in many applications, as they can use renewable heat sources in our surroundings. Even at temperatures we consider o be cold , air ,ground and water contain useful heat that’s continuously replenished by the sun. By applying a little more energy a heat pump can raise the temperature of this heat energy to the level needed for heating a building and hot water
Theoretically the total heat delivered by the Heat pump is equal to the heat extracted from the heat source , plus the amount of drive energy supplied. The normal drive energy for domestic and commercial heat pumps is electricity. Electrically driven heat pumps for heating buildings typically supply 100KW of heat with just 20-40KW of electricity. Many industrial heat pumps can supply 100kw. of heat uby using only 3-10 KW. of electricity.
Environmentally Friendly
Because Heat Pumps consume less primary energy than conventional heating systems, they are an important technology for reducing gas emissions that harm the environment, such as carbon dioxide ( CO2 ) , sulphur dioxide ( SO2 ) and nitrogen oxides ( NOx ) . However the overall environmental impact of electric heat pumps depends very much on how the electricity is produced. For example Heat Pumps driven by electricity produced from Hydropower or renewable energy reduce emissions more significantly than if the electricity is generated coal, oil or gas fired power plants.
How it Works
Almost all heat pumps used in domestic and commercial heating systems are based on a vapour compression cycle. The main components in this type of heat pump system are the compressor , the expansion valve and two heat exchangers referred to as the evaporator and condenser. The components are connected to form a closed circuit as shown in the diagram. A volatile liquid , known as the working fluid or refrigerant circulates through the four components .
In the evaporator the temperature of the refrigerant is kept lower than the temperature of the heat source , causing heat to flow from the heat source to the refrigerant which then evaporates. The refrigerant now in a vapour state is then compressed to a higher pressure and temperature , the hot vapour enters the condenser where it is condensed and gives off useful heat to the heating circuit. The high pressure working fluid (refrigerant ) is then expanded to the evaporator pressure and temperature in the expansion valve. The working fluid is returned to its original state and once again enters the evaporator and the cycle is repeated until the heating load is satisfied.
Heat Sources
The technical and economic performance of a heat pump is closely related to the characteristics of the heat source. There are several heat sources available amoung which are :-
Ambient and exhaust air , soil , ground water , sea/lake/river water , rock (geothermal) and waste water. The two most popular are :-
Soil ( Ground Source )
A water antifreeze mixture is pumped through the evaporator via horizontal pipe loop embedded about one meter below the surface , for a horizontal loop you will need at least three times the internal area of your house . It is important that the soil type is suitable or you may need additional area. If you haven’t got enough area then you will need a vertical bore hole , this tends to be more expensive. In both cases the loop(s) length must be matched to the heating load.
Ambient Air
The air to water heat pump is getting more and more popular because there is no need for costly ground loops. This type of heat pump is generally perceived to be slightly less efficient than ground source heat pumps because of the electricity used to run the fans and the occasional need to defrost the evaporator. However the modern air to water heat pumps are achieving a high COP ( coefficient of performance ) and SPF ( seasonal performance factor )
