F Find Heat Pump

What a heat pump installation actually involves

A typical UK heat pump install takes 2–5 working days on-site, plus 2–6 weeks beforehand for survey, design and grant processing. Here's the sequence, what a good installer does at each stage, and what disruption to expect at home.

Week 0: enquiry & initial conversation

  • You contact 2–3 MCS-certified, BUS-registered installers.
  • They ask about property type, age, insulation, current heating, and rough number of radiators.
  • A good installer doesn't quote at this stage — they ask to survey.

Weeks 1–2: site survey

This is the most important stage. A proper MCS heat-loss survey is 2–4 hours on-site, measuring:

  • Each room's floor area, window area, and existing radiator output.
  • Wall construction (solid brick, cavity, timber-frame) and insulation state.
  • Loft insulation depth and condition.
  • Existing pipework (microbore, 22 mm, 28 mm) — this affects whether pipework needs upgrading.
  • Outdoor unit location options and condensate drain routing.
  • Hot water cylinder location.
  • Electrical supply: consumer unit capacity and the main fuse rating (often a stumbling block).

Weeks 2–4: design and quote

The installer sends a written design pack including:

  • Total heat loss in kW.
  • Specified heat pump model and kW output.
  • Designed flow temperature.
  • Estimated SCOP.
  • Radiators to be replaced (room by room).
  • Hot water cylinder size and brand.
  • Itemised quote with BUS grant deduction clearly shown.

Weeks 4–6: BUS voucher and contract

  • The installer applies to Ofgem for a Boiler Upgrade Scheme voucher.
  • Voucher issued (typically 1–2 weeks).
  • You sign the contract with a small deposit (10–20% is normal).
  • Installation date confirmed, typically 4–10 weeks out depending on the installer's diary and equipment lead times.

Day 1 on-site: prep and outdoor unit

  • Installers arrive (typically 2 engineers).
  • Outdoor unit position confirmed and base prepared (concrete plinth or wall brackets).
  • Outdoor unit delivered, lifted into place, levelled.
  • Refrigerant pipework routed to the indoor location, drilling 1–2 wall penetrations.
  • Condensate drain routed to a downpipe or soakaway.

Day 2: indoor plumbing and cylinder

  • Old hot water cylinder removed if applicable. Combi boiler isolated (or removed if you're going full electric).
  • New unvented cylinder installed.
  • Heat pump heat exchanger and buffer connected.
  • Hot water mains pressure tested.
  • System filled, vented, flushed.

Day 3: radiator changes and electrical

  • Identified radiators replaced (usually 1–3, sometimes none).
  • Smart thermostat and weather-compensation sensor installed.
  • Electrical works: dedicated heat pump circuit, isolators, possibly a consumer unit upgrade.

Day 4: commissioning and handover

  • System started and run through manufacturer commissioning procedure.
  • Flow temperature set, weather compensation curve adjusted.
  • SCOP verified against design.
  • Installer walks you through controls.
  • MCS certificate issued.
  • Building Control notification submitted (if required).
  • Manufacturer warranty registered.

What disruption to expect at home

  • No heating for a few hours during cylinder swap on day 2.
  • No hot water for half a day on day 2.
  • Outdoor noise while drilling and craning the outdoor unit.
  • Indoor mess in the rooms with radiator changes — installers should sheet up.
  • Electrical disruption for 1–2 hours if the consumer unit is being upgraded.

What "fully commissioned" should mean

By the end of day 4 you should receive:

  • MCS certificate (PDF and original on paper).
  • Manufacturer commissioning report.
  • Heat-loss survey and design pack.
  • Warranty registration confirmations.
  • Quick-start guide for the controls.
  • Annual servicing booking for ~12 months out.

Common things that go wrong (and aren't deal-breakers)

  • Refrigerant leak during commissioning. Caught at install. Installer fixes and re-charges.
  • Flow temperature too high on day 4. Comes down as the installer dials in weather compensation over the first cold week.
  • One room slow to heat. Usually a balancing issue — fixed without parts.
  • Cylinder noise. Air in the system; bleeds out over a week.

Find your installer

Start with our regional directory and use the questions to ask guide.

Sources