Heat Pump Installation Time & Process UK 2026

The full UK timeline at a glance

Week 1 — Survey day

The installer visits for 90 minutes to 3 hours and does:

• Loft and floor void inspection (insulation, pipework routes)
• Existing radiator size measurements (room-by-room)
• EPC and U-value review
• Heat loss calculation per BS EN 12831 (room-by-room)
• Site assessment for outdoor unit (boundary distance, noise, drainage)
• Electrical assessment (supply capacity, fuse board)
• Cylinder location and pipework route planning

Most installers issue a written quote within 5-7 days of the survey. If they need longer than 14 days, push back — slow quoters often mean slow installs.

Week 2 — Quote review and contract

A proper quote includes:

• Heat pump make, model, size
• Cylinder size and brand
• Itemised radiator upgrades (which rooms, what BTU output, cost each)
• Pipework upgrades (if any) — 22mm primary flow is now standard
• Controls package (weather compensation, app integration)
• Calculated SCOP at design conditions
• Estimated annual running cost on stated tariff
• Workmanship warranty scheme (HIES, RECC or QANW)
• BUS grant amount and payment terms
• Total cost gross, BUS deduction, net to pay

If any of these are missing, ask. Don't sign without seeing the heat loss calc.

Weeks 2-3 — BUS grant application

Your installer submits the BUS application to MCS on your behalf. MCS approval typically takes 10 working days (sometimes faster). You don't need to do anything except sign the customer authorisation form your installer provides.

Note: BUS funding is allocated quarterly. If you're applying in Q1 or Q4, watch for budget exhaustion — installers will warn you if your application risks falling into the next quarter.

See: Boiler Upgrade Scheme 2026 Guide

Weeks 3-5 — Equipment order and lead times

Typical UK lead times in 2026:

• Mitsubishi Ecodan: 2-3 weeks
• Vaillant aroTHERM Plus: 2-4 weeks
• Daikin Altherma 3: 3-4 weeks
• Grant Aerona 290: 1-2 weeks (Grant holds UK stock)
• Samsung/LG: 3-5 weeks
• Worcester Bosch: 4-6 weeks
• Nibe: 8-12 weeks (Scandinavian import)

Winter (Oct-Jan) lead times typically double. Order in March-May for the fastest turnaround.

Weeks 4-6 — Optional pre-work (radiator upgrades)

If your survey found undersized radiators (very common in older homes), the installer may schedule a 1-2 day visit before the main install to swap them. This minimises disruption during the main install week.

Typical scope:

• Replace 4-8 radiators with K2 (double-panel) or K3 (triple-panel) units
• Cost: £150-300 per radiator including fitting (often included in main quote)
• Heat will be off for 4-8 hours during the swap (plan a warm-weather week)

Weeks 5-7 — The main install (3-5 days on-site)

Day 1 — Outdoor unit and base

• Concrete base or wall bracket installed
• Outdoor unit positioned (typically 2 engineers, takes 4-6 hours)
• Initial pipework run to indoor location
• Condensate drain installed

Day 2 — Indoor cylinder and primary pipework

• Old gas boiler and HW cylinder removed (if applicable)
• New unvented cylinder installed (typically 200-300L)
• Primary flow and return pipework run (often through airing cupboard or utility)
• Heating system flushed

Day 3 — Electrics and controls

• Dedicated electrical supply run from consumer unit (often a new 30A breaker)
• Outdoor unit wired
• Controller installed (Mitsubishi MELCloud, Vaillant sensoComfort, Daikin Madoka)
• Weather compensation outdoor sensor mounted
• First-fire test on heating

Day 4 — Refrigerant connection, vacuum, gas charge

• Refrigerant lines connected outdoor-to-indoor
• System vacuumed to remove air (90+ minutes)
• R290 or R32 charge added
• Full pressure leak test
• Initial commissioning run

Day 5 — Commissioning and handover (often 1-2 weeks later)

• Final balancing of radiators (Engineers Lockshield valves set)
• Flow temperature optimised to design target
• Weather compensation curve programmed
• App installed on customer phone (MELCloud / Onecta / sensoApp)
• Customer training: app, controls, fault codes, what to do in emergencies
• MCS certificate issued (electronic, also added to MCS database)
• BUS grant deducted from final invoice
• Workmanship warranty registration

Weeks 7-10 — Settling-in and follow-up

A good installer will revisit after 4-6 weeks for a free check-up:

• Review SCOP performance via app
• Re-tune flow temperature if needed
• Adjust weather compensation curve based on real data
• Answer any customer questions on running

This visit is often the single biggest factor in real-world SCOP — first-run settings are typically conservative and can be optimised 0.2-0.4 SCOP higher after data review.

What can slow the timeline

• Planning permission required (listed building, Article 4 zone) — adds 8-12 weeks
• Electrical supply upgrade needed — DNO can take 4-8 weeks for new fuse
• Cylinder location issues — bespoke cylinder lead times 4-6 weeks
• Winter installer backlog — adds 4-6 weeks across most regions
• BUS budget exhaustion at quarter-end — may push install into next quarter

How to keep your install on track

• Get 3 quotes early — don't wait until your boiler dies
• Sign in spring (April-May) for late-summer install (fastest turnaround)
• Pre-clear the install path: empty airing cupboard, remove garden obstructions to outdoor unit site
• Check your consumer unit has space for a new breaker before survey day
• Confirm your insurer is happy with the install (notify them once you have the quote)