Geowarmth Heat Pumps Solar Biomass Renewable Energy

 

The schematic below illustrates the three circuits to consider in a heat pump installation.

 

The heat source is the blue circuit on the left of the diagram.  The heat source can be air, water or the ground.  Most of the heat absorbed by a heat pump is solar energy rather than geothermal from the centre of the earth.  The heating distribution circuit is the red circuit on the right and represents the hot water flowing around the heating system in the property.  The refrigerant circuit is the green circuit in the middle.  This links the external heat source with the heat distribution system and is contained within the heat pump.

 

The three circuits are connected within the heat pump by two heat exchangers.  The energy equation on the diagram is important in understanding the reasons for a heat pump's efficiency.  Typically for every unit of electricity input, three to four units of heat are output by the heat pump.  This is also referred to as the co-efficiency or performance or COP.  As an example the seasonal COP of a Nibe F1155-12 ground source heat pump at a flow temperature of 40oC is 4.59 (source MCS database).  Thus in this example for a power input of 1kW, thermal output of 4.59kW is produced.

 

 

In a typical ground source heat pump installation fluid circulates around the ground in plastic pipes at a lower temperature than the ground, say at 5oC.  This creates a heat gradient and draws heat from the ground into the fluid in the pipe.  The fluid passes through an evaporator (heat exchanger) in the heat pump and the heat extracted from the ground is absorbed by the refrigerant which circulates around the heat pump.  The refrigerant becomes a gas and is compressed in a compressor which causes further heat.  The pressurized refrigerant then passes over another heat exchanger called a condenser where the heat is transferred to the building’s underfloor or radiator pipe work.  Having given up its heat, the refrigerant passes through an expansion valve where its pressure and temperature further reduces returning it to a liquid state to start the cycle again.  The main power consumer in a heat pump is the compressor, but the majority of the energy comes from the environment.

 

 Air conditioning systems can be used to provide space heating, cooling and domestic hot water.

In heating mode, an external heat exchanger or evaporator absorbs heat from the air and transfers it to a refrigerant vapour in the refrigerant circuit. This passes in to a compressor where the vapour pressure is increased which creates an increase in temperature. This higher temperature pressurised refrigerant passes through another heat exchanger or condenser, where it liquefies and transfers heat that can be delivered to the property via the air in the building. The process is also known as a vapour compression cycle.

In cooling mode the process is operated in reverse with heat in the building extracted from the air and disposed of to atmosphere. A variation on this involves heat recovery where the extracted heat from some parts of a building can be used to warm other parts of the property or using a heat pump boiler to provide domestic hot water.

Air conditioning systems are based on heat pump technology with components common to those is a refrigerator.

The efficiency of heat pumps arises from some of the heat or cooling coming from the atmosphere rather than from electricity. There is a ratio of heat delivered to electrical power consumed known as the Coefficient of Performance or COP. In cooling mode this ratio is known as the Energy Efficiency Ratio or EER. Typical values are between 3 and 4 so for every 1kW of electricity input the equivalent of 3 or 4kW of heating or cooling is achieved. Air conditioning heat pumps thus provide a very cost effective way of heating and cooling a building compared with direct electricity and can also compare favourably with other forms of heating.

 

 R22 is a hydrochlorofluorocarbon (HCFC) and has been common in air conditioning in the past. R22 gas can no longer be supplied in the UK or used for servicing and maintenance of existing systems. To do so would be illegal. R22 is harmful to the ozone hence it is now banned.

It is therefore necessary to replace existing R22 air conditioning with a more modern alternative such as an inverter controlled system containing the more efficient refrigerant R410A. Geowarmth can offer a rnage of solutions from single room air conditioners to whole building simultaneous heating and cooling systems.

Increases in efficiency of 30-50% should be possible by switching to R410A inverter controlled air conditioning units from old
R22 systems. Higher efficiency means lower electricity consumption and less CO2 emissions.

The cost of change need not be a burden. Various tax incentives are available for replacing old systems such as Enhanced Capital Allowances (ECAs) or Annual Investment Allowances which can allow businesses to write off the cost against tax in year one. In addition finance to businesses is also available.

Please contact us for a bespoke solution