How a ground source heat pump works

Ground source heat pumps are very efficient and are well established and have been around since the 1950’s becoming increasingly popular due to environmental issues. They produce three to four times the amount of heat energy for every electrical unit required to run them.

A ground source heat pump operates by extracting geothermal energy from the ground. The temperature at a metre underground stays at about eight degrees celsius to thirteen degrees Celsius all year around. This heat energy is then used to provide hot water and central heating for your home or an office building. Under floor heating is the best option for central heating when using ground source or air source heat pumps because they generate the lower temperatures required for under floor heating.

How a ground source heat pump works

Pipes are laid in the ground that contain a mixture of water and anti freeze they are either laid down in a trench or in a bore hole in a coil formation and the fluid in the pipe is pumped around to extract the heat from the surrounding earth. The energy extracted into the fluid in the buried pipes in the ground will be replaced but the suns rays heating up the earth so there is a constant source of renewable energy to be absorbed into the fluid in the buried pipes.

The stored energy extracted from the earth that is stored in the loop in the ground is then transferred to the refrigerant in the heat pipe using the evaporator.

The compressor then moves the refrigerant vapour round the pump and compresses the refrigerant at the same time which heats the refrigerant gas to the level needed for your domestic hot water or central heating circuit.

You will notice that when you pump a bicycle tyre up the pump gets hot as the air is compressed this is the same principle. The compressed refrigerant vapour will then reach the condenser within the heat pump at which point the heat from the vapour will be transferred to the hot water cylinder or central heating. The cooled refrigerant will then repeat this process over and over again to build up heat in the hot water cylinder or central heating , (radiators or under floor heating).

The advantages of ground source heat pumps The pumps are about three to four times more efficient than using electrical emersion heaters because three to four units of heat energy are provided for every unit of electricity. This efficiency can be enhanced further by running the ground source heat pump on economy seven. They are also quieter than air source heat pumps.

There is a constant source of energy throughout the year even in the colder months because the average temperature a metre under the ground is between eight and thirteen degrees celsius

As already stated ground source heat pumps and air source heat pumps are far more efficient than using electricity but they are also far cheaper than oil and liquid petroleum gas and due to the efficiency of ground source heat pumps compared to electric the costs become comparable to mains gas. Although the greatest cost savings will be for households or businesses that are not connected to the gas mains

ground source heat pumps have a long life span of around twenty five years due to there simplicity

A ground source heat pump is quieter to run than an air source heat pump and therefore can be mounted within the home will less disturbance to the occupants

They take longer to heat up a hot water cylinder than a normal boiler

The disadvantages of a ground source heat pumps

They are more expensive to install than an air source heat pump because they may require far more land if you are to lay the pipes in a trench, even if you are not using a trench to lay the pipes you will need a bore hole to mount the pipes vertically

Should I fit a ground source heat pump to my home?

• A ground source heat pump generates lower temperatures than a traditional gas boiler (around 50 degrees Celsius) therefore they should be used in conjunction with good insulation. So ensure that your property already retains all of its existing heat efficiently via cavity wall insulation, draught excluders etc.
• More space will be needed for the pipes to be laid in a trench or bore hole but because of this they can extract a consistent level of energy all year round because the ground temperature a metre down stays at between eight and thirteen degrees celsius.
• You will need larger radiators than a normal gas boiler central heating system this is why under floor heating is preferable for ground source heat pumps.
• It will prove cheaper to install if you are not adding to an existing central heating system, therefore a new property is always the best solution.
• You can combine the install with a solar water heating panel that will heat your water in your hot water cylinder via its own dedicated coil.
• The greatest savings are in area that are not connected to the gas mains and therefore if you are using heating oil electricity or LPG you will get the best savings and will use between a third and a quarter of the electricity required to run an immersion heater.
• They produce around forty percent less emissions than a condensing boiler.
• You are no longer reliant upon a rapidly depleting fossil fuels air is inexhaustible or held to ransom to energy price rises.
• The heat pumps can be used for hot water, central heating and swimming pools.
• The ground source heat pumps have a three year guarantee.
• They use modern compressors that are highly efficient

General questions

What is the cost to install a ground source heat pump Estimate for ground source heat are at around £5500 upwards a large part of this being for the trench to be dug out or the vertical bore hole.

How much does it cost to run

It will reduce your current electricity consumption to about a third to a quarter of your current consumption.
Heating oil savings are comparable with the cost savings on electricity and are estimated at about eight to nine hundred pounds a year.

Can I get a grant?

grants are available for ground source heat pumps

What about under floor heating?

Ground source heat pumps work very well with under floor heating and because under floor heating operates at the lower temperatures provided by a ground source heat pump

What should I save in costs?

It will reduce your current electricity consumption to about a third to a quarter of your current consumption and approximate savings for ground
source heat pump providing your central heating are between three hundred and nine hundred pounds a year.

Gas and coal cost savings are estimated at three hundred pounds and oil at around six hundred pounds and electricity at around eight hundred and fifty
pounds. These figures can be further improved by adding a solar water heating panel that will provide all of your hot water for around six to
seven months of the year and part of your hot water for another two to three months. But remember these are all approximations and will fluctuate
depending upon your own personal demands for your hot water and your central heating supply

Installing in a smaller property with limited space

You can fit ground source heat pumps to smaller properties but you will need to use a more expensive bore hole for the pipe. It would be far more effective to fit an air source heat pump in these scenarios

This entry was posted on Tuesday, December 16th, 2008 at 11:31 am and is filed under Green Energy. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.