Heat Pump
Introduction

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Heat pumps offer a sustainable and environmentally friendly solution to meeting the heating and cooling requirements of buildings across the UK. This well-established technology uses a small amount of electricity to power a clever thermodynamic process which transfers low temperature thermal energy from one location and distributes it at a higher temperature in another. By utilising the existing thermal energy from the surrounding environment, heat pumps significantly reduce CO₂ emissions which would otherwise contribute to global warming.

This process is extremely efficient, with the potential to produce 4 or 5 kWh of useful thermal energy for every 1 kWh of electricity consumed ². Read here how this process works. The efficient performance of a heat pump has the benefits of eliminating local emissions, significantly reduces running emissions and reducing system running costs.

Heat pumps provide space heating and hot water using a small quantity of electricity to process free thermal energy from the local environment

At Renewables First we specialise in water-source and ground-source heat pump projects (not air-source), leading all stages from initial feasibility assessment to system design, installation and commissioning. With experience in large and small-scale renewable technology installations we have a wealth of experience to bring to your heat pump project.

You can take confidence knowing that our domestic installations are performed to the highest standards and are MCS certified ¹ – a requirement for application to government backed grants such as the Boiler Upgrade Scheme (BUS).

In both water-source and ground-source installations the heat pump is located inside the building or an adjoining structure. Only the collection system and its connecting pipework are located out of sight externally, ensuring minimal visual impact upon the property. There are also no requirements for external vents or flues. The image below shows a typical heat pump installation. The collector type will change depending upon the source but the remaining system is consistent with most installations.

Typical water-sourced heat pump system installation schematic

Water-source heat pumps

Water-source heat pumps use a static or flowing water course as the heat source, so typically a river, canal or lake, though wells and the sea can also be used. The amount of heat that can be extracted from water is much higher than the ground, and in the case of flowing water there is no risk of depleting the resource of heat because it is being continuously replenished. There are two types of water-source heat pump installation, ‘open-loop’ and ‘closed-loop’. In ‘open loop’ the source water is abstracted (pumped out) of the source and passed through a Primary heat exchanger, and from the other side of the Primary heat exchanger the heat is transferred to the heat pump. In ‘closed-loop’ systems the heat collectors (FireFlo or pond mats) are located in the source water, so only the heat is extracted from the water course and not the actual water. Open loop tends to be used for larger commercial systems, and closed loop for smaller domestic systems – generally speaking, close-loop is better if it is possible. Because of the higher ‘specific heat capacity’ of water and the steadier temperatures found in water bodies, the CoPs that can be obtained from water-source heat pumps typically range from 3 to 5.5 ² in well-designed systems.

Want to find out more about water-sourced heat pumps? Head over to our Heat Pump Learning Centre where you’ll find answers to the most frequently asked questions.

Renewables First have considerable experience and full project capability, from initial feasibility study through to system design and installation. To read about the services we offer and to make an enquiry, please head to either our commercial or domestic heat pump web pages.

Ground-source heat pumps

Ground-source heat pumps benefit from the steadier and warmer winter time temperatures available from the ground compared to ambient air. Where land area allows, heat is extracted from the ground using a horizontal collection system. Here many hundreds of meters of slinky pipe are buried in shallow trenches (approx. 1.2 m deep). As a general guide one 10 m long trench will be required per kilowatt of heat pump capacity, with the heat pump capacity being determined by the size and heat loss of the property. Where land area is limited a vertical collector array is installed with single loops of pipe being sunk into boreholes which can be hundreds of meters deep. The number and depth of the boreholes is determined by the heat pump capacity and the geological makeup of the ground. Vertical systems are less disruptive but more expensive due to the costs of skilled geothermal drilling contractors. Well-designed ground-source systems can have CoPs of 3 to 4.5 ², sometimes even better. At the upper end of these CoPs the finances of a ground–source heat pump can get attractive.

Want to find out more about ground-sourced heat pumps? Head over to our Heat Pump Learning Centre where you’ll find answers to the most frequently asked questions.

Renewables First have considerable experience and full project capability, from initial feasibility study through to system design and installation. To read in detail about the services we offer and to make an enquiry please head to either our commercial or domestic heat pump web pages.

1. MCS certification for Heat Pumps is provided through an umbrella scheme from Kensa Heat Pumps, where we are their installation contractor and are responsible for the design and efficient operation of the system. We can provide plumbing & electrical contractors or we can utilise your own local contractors.

2. Coefficient of Performance (CoP)  will depend on the source temperature of the collector and the desired supply temperature. Please see the following link from the European Heat Pump Association (EHPA) for their verification of the likely CoP White_Paper_Heat_pumps-1.pdf(page 32).