Design is what separates a comfortable, economical system from a disappointing one. Heat pumps run most efficiently at low flow temperatures, around 35–50°C, so the survey checks every room's heat loss against the radiator in it and sizes the unit to the whole house rather than to the old boiler's output. Weather compensation controls then adjust the water temperature to the weather outside, so the system runs gently for long periods instead of in short bursts.
In West Sussex, cylinder space is planned with you, often in an airing cupboard, utility room or garage. For older properties in West Sussex, the heat loss calculation looks closely at solid walls, single glazing and draughts before any unit is sized. Installers working in West Sussex plan the order of work so heating and hot water are off for as short a time as practical.
Who it suits
- Households with room for a hot water cylinder
- Owners and landlords in England and Wales eligible for the Boiler Upgrade Scheme
- Homes replacing a gas, oil, LPG or electric heating system
- Houses with reasonable insulation, or a plan to improve it
Grants and rules for heat pumps in England
Homes in West Sussex can use the Boiler Upgrade Scheme, which takes £7,500 off the cost of an air source heat pump when it replaces fossil-fuel or electric heating. Replacing oil or LPG heating qualifies for £9,000 for installations from 21 July 2026 to 31 March 2027, and air-to-air systems for £2,500. The MCS-certified installer named in your quote applies for the grant and deducts it from the price.
Installing heat pumps is zero-rated for VAT across the UK until 31 March 2027. Since 29 May 2025, permitted development in England allows up to two air source heat pumps on a house, each up to 1.5 m³, with no blanket 1 m boundary rule — the installation must still meet the MCS planning standards, including the noise check. Listed buildings, flats and some conservation-area positions need extra consent, which we check at survey.
Air source heat pump installation prices in West Sussex
Here are typical prices for air source heat pump installation in West Sussex, installed and including VAT. Use the guide price tool for a figure based on your home, then a survey confirms it in writing.
| Home | Typical size | Installed guide price | After £7,500 grant |
|---|---|---|---|
| 1–2 bedroom flat or small terrace | 4–5 kW | £9,900–£13,000 | £2,400–£5,500 |
| 2–3 bedroom terrace or semi | 5–7 kW | £10,900–£14,050 | £3,400–£6,550 |
| 3 bedroom semi or small detached | 6–9 kW | £12,500–£16,100 | £5,000–£8,600 |
| 4 bedroom detached | 8–12 kW | £14,550–£18,700 | £7,050–£11,200 |
| 5+ bedroom or larger older house | 11–16 kW | £17,150–£23,400 | £9,650–£15,900 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning.
Towns we cover in West Sussex
We cover 14 towns in West Sussex for air source heat pump installation. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Crawley | RH11 | Horley | 7 h 53 min |
| Worthing | BN11 | Shoreham-by-Sea | 7 h 56 min |
| Bognor Regis | PO21 | Chichester | 7 h 57 min |
| Littlehampton | BN17 | Arundel | 7 h 56 min |
| Horsham | RH12 | Crawley | 7 h 54 min |
| Haywards Heath | RH16 | Burgess Hill | 7 h 55 min |
| Chichester | PO19 | Bognor Regis | 7 h 56 min |
| Burgess Hill | RH15 | Haywards Heath | 7 h 55 min |
| East Grinstead | RH19 | Crawley | 7 h 53 min |
| Shoreham-by-Sea | BN43 | Worthing | 7 h 56 min |
| Emsworth | PO10 | Havant | 7 h 56 min |
| Arundel | BN18 | Littlehampton | 7 h 56 min |
| Midhurst | GU29 | Petworth | 7 h 55 min |
| Petworth | GU28 | Midhurst | 7 h 55 min |
Air source heat pump installation questions
What grants can I get for a heat pump?
It depends on where you live. In England and Wales the Boiler Upgrade Scheme gives £7,500 towards an air-to-water heat pump, which the installer claims and deducts from your quote. In Scotland, Home Energy Scotland offers a grant of up to £7,500, with up to £1,500 more for eligible rural and island homes, but you need a written funding offer before work starts. Northern Ireland has no dedicated homeowner heat pump grant at present.
How long does an air source heat pump installation take?
A typical home installation takes 2–4 days on site. It takes longer if several radiators are being replaced, pipework is being upgraded or the cylinder is going in a new location. Your quote sets out the expected programme, including when you will be without heating and hot water. Timings are typical rather than fixed, because older homes sometimes reveal surprises once floorboards are lifted.
Can I cancel after accepting the quote?
Nothing is ordered until you accept the written quote. Where the contract is agreed away from our premises, for example at your kitchen table, you can cancel within 14 days under the Consumer Contracts Regulations 2013. If you ask us to start sooner and then cancel, you pay only for work done up to that point.
Will an air source heat pump be noisy?
Heat pumps are designed to run quietly, but where the unit sits makes a real difference. The survey looks for a position away from bedroom windows and neighbours, with clear airflow, and the installation must pass the MCS noise assessment. The fan is most noticeable on very cold days when the unit works hardest, and a little vapour during the periodic defrost is normal.