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London — Tier-1 Pillar

London Air-Source Heat Pump — MCS, BUS Grant, Planning, Noise

London air-source heat pump reality. MCS-certified installer, £7,500 Boiler Upgrade Scheme (BUS) grant, Permitted Development (usually), MCS 020 noise assessment, hot-water cylinder, radiator resize, Part L 2021. £10K-£22K typical before grant.

~2 min read·Updated 2026-04-23

Air-source heat pump installation is the centrepiece of the Future Homes Standard transition. The Boiler Upgrade Scheme (BUS) provides a £7,500 grant for replacing a fossil-fuel boiler with an air-source heat pump — payable to an MCS-certified installer on completion. The grant covers roughly 35-50% of a typical London installation cost (£10,000-£22,000 before grant).

Planning-wise, air-source heat pump external units fall under Permitted Development in most cases (GPDO 2015 Schedule 2 Part 14 Class G) — subject to siting, size, and MCS 020 noise assessment. The unit must be sited at least 1 m from the property boundary, must not exceed 0.6 cubic metres, must be on ground or roof (not forward of the principal elevation), and must pass MCS 020 noise at the nearest neighbour's windows. In conservation areas and on listed buildings, full planning or Listed Building Consent is frequently required.

The practical constraint on London terraces is the combination of external siting, pipework to the indoor cylinder, and radiator resizing. Heat pumps run at lower flow temperatures (35-50°C) than gas boilers (70-80°C), so existing radiators usually need upsizing by 30-60% — which means plumbing disturbance in every room.

AskBaily routes London air-source heat pump installations to MCS-certified installers with BUS grant experience, MCS 020 noise assessment capability, and track records on London Victorian/Edwardian terrace conversions.

ASHP compliance checklist

  • MCS. Installer certification required for BUS grant + SEG eligibility.
  • BUS grant. £7,500 for ASHP. Paid to installer on completion.
  • Planning. PD on most unlisted properties with MCS 020 noise compliance. Conservation / listed: full planning likely.
  • MCS 020. Noise assessment at nearest neighbour's windows.
  • Part L 2021. U-value uplift often paired with ASHP install to maintain comfort at lower flow temperature.
  • Radiator resize. 30-60% upsizing typical.

Frequently asked questions

Am I eligible for the Boiler Upgrade Scheme? £7,500 grant for ASHP replacing a fossil-fuel boiler. Property must have a valid EPC (no outstanding loft or cavity insulation recommendations). Installer must be MCS-certified. Grant claimed by installer, not homeowner.

Do I need planning permission for a heat pump in London? Usually not — falls under Permitted Development subject to MCS 020 noise test, siting, and size limits. Conservation areas: often full planning. Listed buildings: Listed Building Consent mandatory. Front-elevation siting typically refused.

How much does a London ASHP installation cost? £10,000-£22,000 before the £7,500 BUS grant. Final cost after grant: £2,500-£14,500. Radiator upsizing and hot-water cylinder add £2,000-£6,000.

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