How to Price an Air Source Heat Pump Installation: Equipment, Labour and BUS Grant Impact

Quick Answer: A typical UK domestic air source heat pump (ASHP) installation prices between £10,500 and £18,500 in 2026 before the £7,500 Boiler Upgrade Scheme (BUS) grant — equivalent to £3,000–£11,000 net to the homeowner. Equipment runs £4,500–£8,500 supplied; labour £4,000–£7,500 across 4–8 days for a 2–3 bed retrofit; cylinder, buffer, controls and pipework £1,500–£3,500. MCS certification (MIS 3005) is mandatory to claim BUS — the certifier-installer can charge a £400–£900 administrative premium for the application paperwork.

Summary

An ASHP install is no longer a niche price exercise. With BUS at £7,500 and gas boilers in the cross-hairs of the future Clean Heat Market Mechanism, demand has hardened. Tradespeople pricing this work are typically MCS-certified plumbing-and-heating firms, not generalists. The pricing model that wins jobs in 2026 is transparent: a fixed equipment line, a banded labour line based on emitter retrofit scope, and a clearly broken-out grant line so the homeowner sees gross-then-net.

The single biggest pricing variable is whether the existing radiator emitters are sized to deliver the design heat load at low flow temperatures (45–55 °C). A direct boiler-swap retrofit where rads are already adequate prices at the lower end. A full house with 1990s-spec single-panel rads needs 4–8 of them upsizing to doubles or triples — that's £1,200–£3,500 of additional plumbing labour and materials before the heat pump is even hung on the wall.

The second biggest variable is hot water. ASHPs pair with an unvented cylinder (typically 200–250 L), which often replaces a vented tank in the airing cupboard. If there's no airing-cupboard space, an integrated cylinder unit or remote-sited cylinder pushes £400–£1,200 of cabinetry, pipework and electrical work onto the quote. MCS calculation and the EPC disclosure for BUS adds paperwork time — bake £400–£900 into the quote for that.

Key Facts

Quick Reference Table

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Job type Typical kW Equipment cost Labour days Total install (gross) Net after £7,500 BUS
1–2 bed flat / small bungalow 5 kW £4,500–£5,800 3–4 £9,500–£13,000 £2,000–£5,500
2–3 bed semi (existing rads OK) 6–7 kW £5,800–£7,200 4–5 £11,000–£14,500 £3,500–£7,000
3 bed semi (4 rads to upsize) 7–8 kW £6,800–£8,000 5–7 £14,000–£18,500 £6,500–£11,000
4 bed detached 9–11 kW £7,500–£9,500 7–9 £15,500–£22,000 £8,000–£14,500
5 bed / period property (high losses) 12–16 kW £9,000–£12,500 8–14 £19,000–£32,000 £11,500–£24,500
Hybrid (ASHP + retain combi for DHW) 5–7 kW £4,800–£6,500 3–5 £8,500–£12,500 £1,000–£5,000

Detailed Guidance

MCS, BUS and the certification premium

MCS certification under MIS 3005 is the gateway to the BUS grant. Installers without it can quote and install but cannot claim BUS — that pushes their net pricing roughly £7,500 above the certified competition for the same scope, which is uncompetitive in the post-grant market.

Pricing the MCS overhead correctly matters:

A clean BUS-eligible quote separates these out so the homeowner can see what they're paying for.

Emitter retrofit — the hidden cost

The headline equipment number is rarely what wrecks an ASHP quote. It's the emitters. ASHPs deliver heat at 45–55 °C flow temperature versus a gas boiler's 70–80 °C — at the lower temperature, a radiator's heat output drops by roughly 50% per BS EN 442 ratings.

Pricing rule for emitter scope:

Existing emitter capacity at 45°C flow vs MCS room heat loss
       │
       ├── Adequate (>110% of design load)   →  No retrofit; price as direct swap
       │
       ├── Marginal (90–110% of design load) →  Upsize 1–3 rads to double/triple
       │                                        Allow £180–£280 per rad upsized
       │                                        + £80–£150 if pipe-tail extension needed
       │
       └── Inadequate (<90% of design load)  →  Whole-house emitter overhaul or
                                                fan coil + UFH retrofit
                                                Allow £1,800–£4,500

Always price the heat loss survey BEFORE quoting the install. Quoting from a kW-per-m² rule of thumb will leave you under-priced in 6 out of 10 retrofits.

Hot water cylinder, buffer and controls

The cylinder is the second-biggest line after the heat pump itself. Specifications matter:

Component Spec (typical) Trade buy 2026 Quote line
Unvented stainless cylinder 200 L G3 to BS EN 12897, 28 mm coil £750–£1,150 £1,250–£1,750 fitted
Unvented cylinder 250 L G3 unvented £900–£1,400 £1,400–£2,000 fitted
Unvented cylinder 300 L G3 unvented £1,150–£1,600 £1,650–£2,300 fitted
Buffer tank 50 L Pre-insulated £180–£300 £350–£550 fitted
Volumiser 25–40 L Pre-insulated £120–£240 £250–£450 fitted
Smart controls (zoning + weather comp) Manufacturer-specific £150–£450 £400–£800 fitted
G3 building notice Notification £80–£150 passed through

Unvented cylinder install is notifiable under Part G3 — installer must be a member of an unvented competent persons scheme (CIPHE, BPEC, etc.) and submit a building notice. Don't price for an unqualified plumber to install the cylinder and bring the certified person back in for sign-off — it costs more on labour overall.

Outdoor unit siting and condensate

Siting decisions drive cost more than they drive aesthetics. Cheap siting choices to avoid:

Condensate from defrost cycles can be 5–15 L per day in winter. The drain run must be frost-protected — either trace-heated or run into a heated internal space. A condensate pump (£90–£150 + £180 fitted) is needed where gravity drain isn't possible.

F-Gas, pre-charged splits and self-contained units

Two equipment archetypes:

  1. Monobloc — refrigerant circuit factory-sealed inside the outdoor unit; only water pipework runs into the house. Easier install, no F-Gas registration needed for the install. Slightly larger outdoor unit footprint. Price at the lower end of equipment costs.
  2. Split — separate indoor and outdoor units linked by refrigerant lines. F-Gas Cat I/II registration required for any work that breaks the circuit (some are pre-charged with up to 6m of pipework so no F-Gas work is needed). Smaller indoor footprint. Price slightly higher.

R290 (propane) units are now common for their high SCOP and natural-refrigerant credentials, but the 1m exclusion zone around openings, drains and ground-floor windows under the unit can limit where they can be sited.

Hybrid and bivalent install pricing

For period properties or homes where full electrification isn't economic, hybrid systems retain a gas combi for DHW and use an ASHP for heating only. These prices sit £2,500–£5,000 below a full ASHP install because:

BUS still applies to hybrid as long as the heat pump is MCS-certified.

Frequently Asked Questions

What's the BUS grant worth in 2026 and how do I apply?

£7,500 for ASHP, £7,500 for ground source, paid to the installer who passes it through as a deduction on the homeowner's invoice. Application is via the MCS portal — the installer uploads the MCS certificate, homeowner consents via email, Ofgem pays the installer within 6–10 weeks. The homeowner does not handle the application, but they must consent.

Do I need planning permission?

Most domestic ASHP installs fall under Permitted Development (Class G). Triggers for full planning are: outdoor unit >0.6 m³ external volume, within 1m of boundary, in a conservation area on a front-garden wall, on a flat roof of a flat or maisonette, or on a listed building. Always check the council's planning portal before committing to siting in the quote.

Why is my quote so much higher than the £7,500 BUS — I thought it was free?

The grant covers a fixed amount, not the whole install. £7,500 typically lands at 50–70% of the gross install cost. For a property needing emitter upsizing, planning permission, or a cylinder relocation, the net-of-grant cost can run £8,000–£12,000.

How long does the install take?

Most 3-bed installs take 4–7 working days on site for a 2-engineer team. A simple combi-to-monobloc with existing adequate emitters can be done in 3 days. A whole-house emitter overhaul plus cylinder relocation can stretch to 10–14 days.

What's the noise rating I need to quote?

MCS 020 limits the unit to 42 dB(A) at the nearest neighbour habitable window (1m off the elevation, 1.5m above ground). 2026 R290 monoblocs typically run 38–50 dB(A) at 1m off the unit, so the calculation matters — site units behind a fence or lined with absorbent material rather than under a kitchen window.

Regulations & Standards