Replacing a gas boiler with a heat pump means removing the boiler and installing an air-to-water heat pump that heats your radiators and a stored hot water cylinder instead. Most UK homes heat with mains gas, so this is the switch many households are weighing up, and the existing radiators and pipework can often be reused with some changes. What needs most planning depends on the type of boiler you have now.
Rear gardens and side returns in Hertfordshire usually offer a sensible spot for the outdoor unit, checked for airflow and neighbours. Semi-detached and terraced houses in Hertfordshire often have an airing cupboard that can be reused for a heat pump cylinder. Households across Hertfordshire moving off gas can have a survey in Hertfordshire that compares running costs on realistic assumptions.
Who it suits
- Boilers that are old, unreliable or due for replacement
- System or regular boiler homes with an existing airing cupboard
- Households ready to give up gas entirely and drop the standing charge
- Combi owners who can find space for a hot water cylinder
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.
There is no VAT on installing a heat pump anywhere in the UK until 31 March 2027. In England most houses can have an air source heat pump under permitted development, provided the unit meets the MCS noise and siting standards; the old 1 m boundary limit was removed on 29 May 2025. We flag listed buildings, flats and sensitive conservation-area positions at survey.
Gas boiler to heat pump prices in Hertfordshire
These are guide prices for Hertfordshire, 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 | £10,000–£13,150 | £2,500–£5,650 |
| 2–3 bedroom terrace or semi | 5–7 kW | £11,050–£14,200 | £3,550–£6,700 |
| 3 bedroom semi or small detached | 6–9 kW | £12,600–£16,300 | £5,100–£8,800 |
| 4 bedroom detached | 8–12 kW | £14,700–£18,900 | £7,200–£11,400 |
| 5+ bedroom or larger older house | 11–16 kW | £17,350–£23,650 | £9,850–£16,150 |
Installed, inc VAT: unit, cylinder, controls, minor pipework and commissioning.
Towns we cover in Hertfordshire
We cover 17 towns in Hertfordshire for replacing a gas boiler with a heat pump. Each links to local guide prices and the grant position for England.
| Town | Postcode district | Nearest town | Midwinter daylight |
|---|---|---|---|
| Hemel Hempstead | HP2 | Berkhamsted | 7 h 47 min |
| Stevenage | SG1 | Hitchin | 7 h 45 min |
| St Albans | AL1 | Radlett | 7 h 47 min |
| Welwyn Garden City | AL8 | Hatfield | 7 h 46 min |
| Cheshunt | EN8 | Hoddesdon | 7 h 47 min |
| Hatfield | AL10 | Welwyn Garden City | 7 h 47 min |
| Bishop's Stortford | CM23 | Ware | 7 h 46 min |
| Hitchin | SG6 | Letchworth Garden City | 7 h 45 min |
| Hoddesdon | EN11 | Ware | 7 h 47 min |
| Letchworth Garden City | SG6 | Hitchin | 7 h 45 min |
| Harpenden | AL5 | St Albans | 7 h 46 min |
| Hertford | SG13 | Ware | 7 h 47 min |
| Berkhamsted | HP4 | Tring | 7 h 47 min |
| Ware | SG12 | Hertford | 7 h 46 min |
| Royston | SG7 | Letchworth Garden City | 7 h 44 min |
| Radlett | WD7 | St Albans | 7 h 48 min |
| Tring | HP23 | Berkhamsted | 7 h 47 min |
Replacing a gas boiler with a heat pump questions
Is there a grant to replace a gas boiler with a heat pump?
In England and Wales, the Boiler Upgrade Scheme gives £7,500 towards an air-to-water heat pump that replaces a gas boiler, for eligible owners of existing homes. The MCS-certified installer applies to Ofgem and deducts the grant from your quote, and Ofgem contacts you to confirm. Scotland has separate Home Energy Scotland funding, and Northern Ireland has no dedicated homeowner grant at present.
Can a heat pump replace a combi boiler?
Yes, but you need room for a hot water cylinder, because heat pumps store hot water rather than heating it on demand. Most homes find a space in a cupboard, utility room, garage or under the stairs, and compact or combined indoor units help where space is tight. The survey measures the options first, so you know where everything will go before you accept the quote.
Do I need to replace the cylinder I already have?
Usually, yes. Older cylinders have a small internal coil designed for water from a boiler at around 60–70°C, and they cannot take in heat quickly enough at the lower temperatures a heat pump runs at. A heat pump cylinder has a larger coil. On its own, a cylinder supplied and fitted has a guide price of £1,200–£2,200, installed and including VAT, though it is normally part of the full system price.
Will my hot water run out with a heat pump?
Not if the cylinder is sized properly for your household. The survey asks how many people live in the home, how many bathrooms you have and whether you prefer baths or showers, then sizes the cylinder to suit. The heat pump reheats the cylinder on a schedule, often overnight and again during the day, and an immersion heater acts as a backup.