Heat Pump Frequently Asked Questions

Here we answer your common questions on heat pumps from how much they cost? to how long they take to install? 


What is a Heat Pump

A heat pump is a renewable technology that extracts natural energy from one place and transfers it to another, to provide energy-efficient, cost-effective space heating and hot water.

How do heat pumps work and what are the different types?

Heat pumps work by harnessing natural energy stored in the ground, rock, lakes, air or water. The system then feeds this renewable energy back to a heat exchanger, to provide efficient, reliable heating and hot water. Thermal Earth supply and install the following types of heat pumps:

Air Source Heat Pumps

Ground Source Heat Pumps

Water Source Heat Pumps

What are the benefits of renewable heating technologies?

Unlike costly fossil fuels, which are dwindling fast, renewable energy is secure, readily available and effectively infinite. Renewable heating systems offer a cost-effective, reliable and energy-efficient way to help us reduce our carbon footprint, and could also deliver long-term fuel savings. By installing a renewable heating technology, you could also be eligible for a one off payment to cover the part of the initial cost of a system install, through the government’s 'Boiler Upgrade Scheme (BUS).

Does my property need to be well insulated to have a heat pump?

Insulation should be up to modern Building Regulation standards to ensure the heat pump both effectively and efficiently heats the property.

Do heat pumps work in cold weather?

Yes. Heat pumps work effectively year-round. The top 15m of the Earth’s surface maintains an average year-round temperature of 12ºC. Ground source heat pumps (GSHPs) use this heat source to supply the energy required to heat domestic water, and a low temperature heating system such as underfloor heating. Air source heat pumps work in a similar way, except they extract available warmth from passing air rather than from the ground. In theory they should be able to extract useful energy from the outside air down to temperatures as low as -15°C. The storage cylinder provides both domestic hot water and a boost of heating energy in the coldest weather.

Can I use my heat pump 24 hours a day?

Yes, absolutely. It’s the most efficient way.

What is the cost of installing a heat pump?

When installing a heat pump, there isn’t a simple one-off cost. There are different aspects of the installation that need to be considered and factored into a quote.


This can vary greatly, dependant on the level of use and how regularly it is checked and serviced. Heat pumps should be serviced annually, with some commercial systems requiring bi-annual servicing arrangements. Generally, the lifespan of a heat pump is expected to be around 20-25 years.


It is essential that you have sufficient external space for the installation of a GSHP, which tends to rule out most urban properties. With regards to cost, the difference between a GSHP and an ASHP is comparitiv but with the groundworks and the costs associated, costs can be significant. There are 'right' and 'wrong' solutions for each project and they should be assessed individually.


Yes a heat pump can produce adequate domestic hot water for all normal use. Generally, we recommend to heat a hot water cylinder to 45 - 50°c. This is warm enough for all washing and bathing. We try to encourage customers to find a happy medium, as the golden rule with all heat pump systems is to keep the output temperature as low as possible while maintaining comfort. Over 50°c normally means that you would need to turn the cold tap on to cool the water, it makes no sense to heat the water and to then cool it at point of use.


Yes. Reverse-cycle heat pumps deliver both heating and cooling very effectively. With air source heat pumps this can only be delivered with full active operation of the compressor but with ground source heat pumps we can provide cooling both active and passively. Passive cooling is the circulation of the brine fluid from the ground collector array directly with the water in the heating/cooling system. This serves has the added benefit of 're-charging' the ground collector during the summer months ready for winter operation.

Is planning permission required?

From 1 December 2011 the installation of an air source heat pump on domestic premises is considered to be permitted development, not needing an application for planning permission, provided ALL the limits and conditions listed below are met. These permitted development rights apply to the installation, alteration or replacement of an air source heat pump on a house or block of flats, or within the curtilage (garden or grounds) of a house or block of flats, including on a building within that curtilage. A block of flats must consist wholly of flats (e.g. should not also contain commercial premises). Limits to be met: Development is permitted only if the air source heat pump installation complies with the Microgeneration Certification Scheme Planning Standards (MCS 020) or equivalent standards. Read more about the scheme. The volume of the air source heat pump’s outdoor compressor unit (including housing) must not exceed 0.6 cubic metres. Only the first installation of an air source heat pump would be permitted development, and only if there is no existing wind turbine on a building or within the curtilage of that property. Additional wind turbines or air source heat pumps at the same property requires an application for planning permission. All parts of the air source heat pump must be at least one metre from the property boundary. Installations on pitched roofs are not permitted development. If installed on a flat roof all parts of the air source heat pump must be at least one metre from the external edge of that roof. Permitted development rights do not apply for installations within the curtilage of a Listed Building or within a site designated as a Scheduled Monument. On land within a Conservation Area or World Heritage Site the air source heat pump must not be installed on a wall or roof which fronts a highway or be nearer to any highway which bounds the property than any part of the building. On land that is not within a Conservation Area or World Heritage Site, the air source heat pump must not be installed on a wall if that wall fronts a highway and any part of that wall is above the level of the ground storey. In addition, the following conditions must also be met. The air source heat pump must be: used solely for heating purposes. removed as soon as reasonably practicable when it is no longer needed for microgeneration. sited, so far as is practicable, to minimise its effect on the external appearance of the building and its effect on the amenity of the area. You may wish to discuss with the Local Planning Authority for your area whether all of these limits and conditions will be met.


For domestic properties it is recommended to pasteurise a hot water cylinder once per week to 60°c and above. The heat pump will already have heated the cylinder to approximately 50°c so to top it an immersion heater can be used. On commercial installations this must be carried out daily rather than weekly.

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