Replacing an old outdoor unit like-for-like has a guide price of £6,000–£9,500, installed and including VAT. Where the system needs re-sizing or other upgrades, the written quote sets out each item. Grant funding rarely applies to replacements, because the Boiler Upgrade Scheme in England and Wales cannot usually fund a home already funded for a heat pump, so we check eligibility before quoting.
New outdoor units in West Sussex may differ in size from the old one, so the base and position are checked at survey. We replace heat pumps in West Sussex whoever fitted the original system, including monobloc and split units. Every replacement in West Sussex starts with a fresh heat loss survey, not just a copy of the old unit's size.
Who it suits
- Heat pumps nearing the end of their typical life with rising repair costs
- Oversized systems that short cycle and cost more to run than expected
- Systems that were undersized and struggle in cold weather
- Units that have failed with a major fault, such as a compressor failure
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.
Heat pump replacement prices in West Sussex
Guide prices for West Sussex, including VAT. We agree the visit rate before anyone attends, so there are no surprises on the day.
| Work | Installed guide price |
|---|---|
| Replacing an old outdoor unit like-for-like | £6,250–£9,900 |
| Full system replacement, 2–3 bedroom terrace or semi | £10,900–£14,050 |
| Full system replacement, 3 bedroom semi or small detached | £12,500–£16,100 |
| Full system replacement, 4 bedroom detached | £14,550–£18,700 |
Installed, inc VAT. Grant funding rarely applies to replacing a heat pump, so these prices are shown without any deduction; we check eligibility at survey.
Towns we cover in West Sussex
We cover 14 towns in West Sussex for heat pump replacement. 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 |
Heat pump replacement questions
Will a new heat pump fit where the old one was?
Sometimes. A new unit may be a different size, weight or shape and may have different clearance requirements, so the existing base and position are checked at survey. The MCS noise assessment is carried out for the new unit, and a different position may be suggested if it improves performance or reduces sound at neighbouring windows.
How much does it cost to replace a heat pump?
Replacing an old outdoor unit like-for-like has a guide price of £6,000–£9,500, installed and including VAT. Re-sizing, a new cylinder, radiator upgrades or new controls add to that, and each is itemised in your written quote. The final price is fixed after a survey, once we know what the existing system needs.
Can I get a grant to replace my heat pump?
Usually not. In England and Wales, the Boiler Upgrade Scheme cannot normally fund a home that has already been funded for a heat pump, and it is aimed at replacing fossil-fuel or electric heating. Your circumstances may differ, so we check eligibility before quoting. In Scotland, check Home Energy Scotland's criteria. Northern Ireland has no dedicated grant at present.
Can I replace just the outdoor unit?
Often, yes, if the rest of the system is sound and correctly designed. The cylinder, controls and radiators can stay where they are compatible with the new unit. Some older cylinders and controllers do not work with a new heat pump, and the survey checks this. If the original design was the problem, replacing only the unit will not fix it.