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What is an Air Source heat pump?

An air source heat pump is a refrigerated product that extracts heat from ambient air which is upgraded to a high grade heat by way of a compressor. This upgraded heat can then be used to heat the property as well as heat hot water up to 50°C. The heat pump output will vary throughout the year so will need to be sized to meet the properties heating requirements.

What is a Ground Source heat pump?

A ground source heat pump is also a refrigerated product that extracts heat from the ground which is upgraded to a high grade heat in exactly the same manner as an air source. The ground temperature is pretty consistent all year round so a heat pump can be matched exactly to the properties requirements. With ground source heat pumps there is a need for an amount of land space to position the ground loops. The loops can be horizontal or vertical which type to use will be dependant on the amount of land space available. To determine the exact length of pipe required a Bespoke Point Prognosis and a Temperature and Thermal properties of the ground survey needs to be done. This is performed by the British Geological Survey team before the installation can take place.

Ground Loops – How it works

Ground loops are fitted in a trench which is excavated at a depth of 1.6 metres at 1 metre wide and the length of trench ranges from 25-50 metres long. A ground loop pipe is terminated at the flow manifold then clipped to the ground alongside one side of the trench. It then returns back to the other side of the trench and terminates to the return manifold. The amount of trenches is dependent on the size of the heat pump and the length of the land space. Each trench must be 0.8 metres apart to prevent too much heat being extracted from one area.

Boreholes – How it works

Borehole loops do not need so much land space as holes are drilled vertically into the ground they are drilled down to about 100 metres. Boreholes can go further down but the cost increases plus the extraction rate changes too. The total amount of drilled holes needed depends on the size of the heat pump. If more than 1 borehole is required then the distance between them must be a minimum of 5-6 metres apart.

What size Heat Pump do I need?

A Heat Pump is sized at design conditions according to MCS guidelines to ensure that the right product is installed for maximum efficiency. The guidelines which all MCS accredited companies have to adhere to are MIS 3005 Installation Standards and MCS Planning Standards. These installation standards ensure that the right product is installed correctly and the planning standards ensure that the heat pump meets all of the noise criteria and impact to the environment. In very cold winter days there may be a requirement for an additional back up heating; if the customer has an oil or gas boiler then this can be used to work together with the heat pump. All new build properties have the highest level of measures to minimise heat loss; so sizing a heat pump should be able cope with 100% of the heating requirements.

The size of the Heat Pump is dependent on the size of the property and what kind of heat emitter is being used. A properties total heat loss is calculated by a room by room sizing exercise; once all rooms have been added together a final figure will be known. A Heat Pump can then be selected based on these figures which can meet 100% of the total heat loss. Lower percentages can still be used by a heat pump however an additional heat source will need to be working alongside it.

What is a Heat Source?

A heat source is basically what heats your home the most common ways of heating a property is by radiators or Underfloor heating. The temperature at the heat source differs; radiators use a high temperature (70°C) and Underfloor heating is much lower (35°C).

Heat Pumps can achieve the same temperatures as a boiler which would mean that the radiators may not need to be changed. Underfloor heating is installed in a lot of new build properties but can be installed in retro-fits as well. Underfloor heating is by far the best way to heat a property as it heats the whole fabric of the building.

Will a Heat Pump heat hot water as well?

A Heat Pump will heat Hot Water but not at the same time as heating, a valve will direct water flow from heating mode to hot water mode. The Cylinder is specially designed to work with Heat Pumps so the likelihood is that it will need to be changed. The reason for this is that the Heat Pump needs to transfer all of its energy into the hot water cylinder by way of heat transference into a coil. Solar Thermal systems can also work with Heat Pumps and again the cylinder will need to cater for both technologies. A Hot Water cylinder’s capacity is calculated using BS 6700 standards which is based on the amount of people using hot water and the amount of bathrooms.

What is CoP?

CoP stands for Co-efficient of Performance in other words it is the efficiency of the Heat Pump’s performance while running. CoP on an Air Source Heat Pump will vary depending on the water temperature and the air temperature, as air temperature increases then the CoP increases. When the air temperature increases and water temperatures are reduced then this improves the CoP as well. By comparison a boiler efficiency is around 85% and an immersion heater is 100%, a Heat Pump will achieve an efficiency of anywhere between 180% - 460%.

Do I need planning permission?

Most domestic Heat Pump installations do not require planning permission; the exceptions are if the building is listed, if the area is of an outstanding natural beauty, or if the property is in a location which could affect the National Grid. An MCS Planning Standards test will be carried out for free during the site survey and advice will be given should you need one.

Do I need to upgrade my Insulation and Windows?

With any kind of property the heat loss is down to how much insulation there is and how tight the air gaps are within the building. The amount of insulation and the type of windows has a direct effect on the heat loss it will determine the size of the heat pump needed. If it is possible to upgrade windows and insulation then it is recommended to do so; this will lower the size of the Heat Pump and the running costs will be much lower. The savings could possibly run into thousands of pounds over the life of the heat pump which could last anything up to 25 years.

Does the Heat Pump need Servicing?

A Heat Pump and the installation does have moving parts and filters in place so it is recommended that the system should be serviced at least once a year. A complete service can consist of checking all components within the heat pump system as well as checking the hot water cylinder. If a property has Underfloor heating then this can be checked as well.




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