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Ground Source Vs. Air Source Heat Pumps – What Are The Main Differences?

Posted by Paul Tuson on May 10th , 2022

Heat pumps are a fantastic way to cheaply power your building’s heating system by harnessing the earth's natural outdoor warmth, ending or reducing your dependence on gas-powered boilers. Using a renewable sink to collect renewable heat and usefully distribute it inside the building (via a powered, liquid evaporator-condenser loop and central heating system) is a more efficient, eco-friendly, and economical alternative to relying on expensive oil and gas boilers.

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There are two different types of heat pump systems to consider for commercial systems, depending on the amount of surrounding land available – ground source and air source heat pumps. Ground and air source pumps have distinct features and strengths that make each better suited to different applications. Read on to find out more.

Ground Source Heat Pumps

Ground heat pumps use buried borehole cylinders (10-100 m deep) or surface-level pipelines (1.2 m deep) to collect and use the earth's ever-present geothermal warmth. Ambient heat from the earth's core and the sun warm underground soil and rocks (to 10-20 °C), providing a steady, year-round source of harvestable heat for the pump. 

By burying the pump's heat sink deep or enclosing it under a thin layer of protective topsoil, heating grids become resilient against poor performance and heavy energy usage during cold snaps and miserable weather. Subsuming the sink and pipeline improves the pump's source-to-water heat retention, saving you money and energy. 

Installation Requirements

To install a ground source heat pump, you will need a suitable amount of open land for the borehole or piping network. Car parks, lawns, and green spaces surrounding office complexes, universities, hospitals etc are ideal for ground source heat pump networks. For the same reason, ground source heat pumps are less suited to commercial buildings in built-up areas.

Ground Source Pump Benefits

  • Eco-friendly, low maintenance
  • Eligible for renewable heat incentive (RHI Scheme, Ofgem) subsidies
  • Excellent compatibility with open spaces (e.g. Fields, gardens, lawns)
  • Great for heavier, denser soils
  • Ground sink installations last for over a century without repair
  • Quicker and more efficient in geothermally active areas
  • Low-profile, 'hideable' heat sinks
  • Tiny to no carbon footprint
  • Underground sinks provide consistent, weather-resistant performance
  • Often classed as a 'permitted development' - no planning permission required

Air Source Heat Pumps

Air source heat pumps extract energy from the surrounding air to power a heating loop, and have a straightforward, basic design and simple installation. The heat sink and evaporator-condenser loop fit into a mountable, all-in-one panel fixed securely to a roof, free-standing mount, or wall. Ambient sunlight and thermal drafts provide the energy to heat an insulated, enclosed sink.

Air source pumps come in two sub-varieties - air-to-air and air-to-water. Air-to-air loops vent warm air directly into an open room on the opposite side of the wall – good for large open spaces and high-ceilinged rooms. Air-to-water pumps use point-injection to indirectly power a fluid based indoor heating system (e.g. radiator circuits, underfloor pipes, water-heater panels, hot water boilers).

Installation Requirements

An air source heat pump can be installed in almost any type of building. The pumps themselves have a small footprint and can be integrated with most commercial heating and air conditioning systems, making them ideal for offices, shops, schools, workshops, warehouses, and public buildings in town centres without the space for a ground source heating loop.

Air Source Pump Benefits

  • Extracts residual warmth from cold air (down to -20 °c)
  • Easier to reach, maintain, and replace
  • Hot, dry weather boosts performance
  • Fits well with photovoltaic (PV) roof panels
  • Great for tightly enclosed or hard-to-access urban builds
  • Minimal Co2 emissions
  • No gas storage, plumbed line, or flue requirements
  • Safe, secure, and reliable
  • Some air source pump models are RHI (microgeneration) grant eligible
  • Small, adaptable, 'fix-anywhere' designs
  • Twenty year working life (per pump)
  • Zero carbon dioxide, carbon monoxide, or chlorofluorocarbons (cfc)

Heat Pump Advice From Lowe and Oliver

Get in touch today with Lowe and Oliver today to find out more about the benefits of air source and ground source heat pumps for your premises. We offer specialist advice on the best choice of heat pump to fit your budget, build, and requirements.

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