The trade-off is efficiency. The hotter the water a heat pump makes, the more electricity it needs for each unit of heat, so a system running at 65°C has a lower seasonal efficiency than one running at 45°C. Good design still matters: weather compensation runs the unit cooler on mild days and only raises the temperature in the coldest weather, which keeps running costs down across the year.
Period houses in West Sussex with original cast-iron radiators may suit a high-temperature unit that works with them. For older West Sussex homes with microbore pipework, a higher flow temperature can avoid lifting floors to replace pipes. In West Sussex, rooms with large bay windows are often the ones where radiator output is checked most carefully.
Who it suits
- Owners who want fewer changes inside the house
- Period and listed homes where the radiators are part of the character
- Older homes where insulation improvements are limited
- Homes with microbore pipework that would be disruptive to replace
Grants and rules for heat pumps in England
In England the Boiler Upgrade Scheme gives £7,500 towards an air source heat pump (£9,000 if it replaces oil or LPG, from 21 July 2026 to 31 March 2027), and since 28 April 2026 a valid EPC is no longer needed. The grant is applied for by the MCS-certified installer and shown as a deduction on your quote.
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.
High-temperature heat pumps prices in West Sussex
These are guide prices for West Sussex, installed and including VAT. Your final price is fixed in a written quote after the survey and depends on the heat loss of the house, the radiators that need changing and where the unit goes.
| 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. A high-temperature unit typically adds £1,500–£3,000.
Towns we cover in West Sussex
We cover 14 towns in West Sussex for high-temperature heat pumps. 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 |
High-temperature heat pumps questions
Are high-temperature heat pumps less efficient?
Yes, when they run hot. Every heat pump uses more electricity per unit of heat as the flow temperature rises, so a unit running at 70°C is less efficient than one running at 45°C. With weather compensation it runs cooler for much of the year, which narrows the gap. The design aims to keep the maximum temperature as low as your radiators allow.
Is a high-temperature heat pump right for a listed building?
It can be, because it reduces the need to replace period radiators or lift historic floors for new pipework. The outdoor unit position still matters: in England, listed buildings need listed building consent for external works, and the other nations have their own rules. We check what applies at survey and look for discreet positions, such as a rear courtyard or behind an outbuilding.
Do I still need a hot water cylinder?
Yes. Like other air-to-water heat pumps, a high-temperature unit heats a stored cylinder rather than supplying hot water on demand. Its higher output temperature can help the cylinder reach the temperature needed for its periodic legionella cycle with less reliance on the immersion heater. The cylinder is sized for your household at survey.
Can a heat pump work with my existing radiators?
Often, yes, especially with a high-temperature unit. Standard heat pumps run most efficiently at 35–50°C, so some radiators may be too small at those temperatures. A high-temperature unit can run at around 65–75°C, so existing radiators can usually heat rooms much as they do with a boiler, at a cost in efficiency. The survey checks every radiator against its room's heat loss.