An air source heat pump should be designed as a complete heating and hot-water system, not treated as an outdoor appliance that simply replaces a boiler. Older construction, later extensions, different radiators and household hot-water routines can all change the right specification.
Green Energy Homes provides survey-led air source heat pump installation in Sevenoaks for suitable properties. Our main air source heat pump guide explains the technology, costs and installation process; this page looks more closely at the property checks that turn an initial enquiry into a workable local proposal.
Two homes with a similar floor area can need very different heating systems. Wall, roof and floor construction, glazing, airtightness, extensions and the temperatures expected in each room all affect heat loss. A room-by-room calculation gives the design a reliable starting point.
That information is used to select the heat pump and to test how it may perform at an appropriate flow temperature. It also identifies where a measured fabric improvement could reduce demand. The aim is not to insist that every older home must be rebuilt first, but to make the consequences of the existing building clear before equipment is chosen.
A heat pump normally operates differently from a boiler, so the existing emitters cannot be approved by appearance alone. Radiator output at the proposed water temperature, pipe sizes, system volume and any underfloor heating zones all need reviewing as one distribution system.
Some radiators may remain suitable; others may need increasing in size or replacing. Where floor heating is part of a renovation, it can be designed alongside the heat pump rather than added later. This targeted approach is more useful than promising that every radiator can stay or assuming they must all be changed.
An air-to-water heat pump generally uses stored domestic hot water rather than producing it instantly like a combi boiler. Cylinder capacity, recovery time, available cupboard or plant space and the pattern of baths and showers therefore belong in the early design.
The survey should also agree the route between the outdoor unit, indoor equipment, cylinder and heating system. In a carefully finished or extended Sevenoaks home, resolving that route before work starts can prevent avoidable boxing, long pipe runs or the loss of useful storage.
The outdoor unit needs clear airflow, service access, drainage and a stable base. Its position should also be checked for sound at nearby windows and boundaries, cable and pipe routes, visual impact and the way planting may grow around it. A screen or enclosure must not compromise the manufacturer’s clearances.
Many domestic installations can be permitted development when the relevant limits and MCS planning standard are met, but listed buildings, conservation areas, flats and restricted development rights can require a different route. Position and permissions should be tested before the final design and price are fixed.
The Boiler Upgrade Scheme can reduce the upfront cost of an eligible installation, but funding does not prove that a particular property or design is suitable. Green Energy Homes can check the current route as part of an MCS-compliant proposal; our Boiler Upgrade Scheme guide explains the process.
The quotation should separately identify the heat pump, cylinder, emitter or pipework changes, electrical work, controls, commissioning and handover. Customers can also review our accreditations and consumer protections before making a decision.
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Possibly. Suitability depends on measured heat loss, emitter capacity, pipework, hot-water demand, electrical provision and an acceptable outdoor position. Older or mixed construction does not create an automatic yes or no. The survey should show what can remain, what may need improving and the performance assumptions behind the proposal.
Not necessarily. Each radiator should be checked for the heat it can deliver at the proposed water temperature. Some may already be adequate, while particular rooms may need a larger or different emitter. Pipework and system flow also matter, so radiator decisions should follow the whole-system calculation.
A suitable position provides airflow, maintenance access, drainage and a practical route to the indoor system. Sound at neighbouring windows and boundaries, appearance, planning rules and future growth of planting should also be considered. The most hidden corner is not always suitable if it traps air or blocks servicing.
Yes. Correctly designed underfloor heating can provide useful output at the lower water temperatures that often suit a heat pump. Heat loss, floor construction, available heated area, pipe spacing and controls still need calculation. Existing floor circuits should be checked rather than assumed compatible.
An air-to-water system can provide space heating and stored domestic hot water, normally using a suitable cylinder. The design should reflect household demand, available space, recovery and any immersion or hygiene cycle. It should not be described as delivering unlimited hot water on demand like a combi boiler.
At the time of writing, eligible air-to-water heat pumps can receive £7,500. Until 31 March 2027, this rises to £9,000 for qualifying off-gas-grid properties replacing oil or LPG heating. The scheme is installer-led and subject to current eligibility and technical rules, which should be checked before a contract is agreed.
Tell us about the existing heating, hot-water routine, any planned renovation and possible outdoor positions. We can establish the information needed, check the current grant route and arrange a detailed assessment for your Sevenoaks property.
