Heat Pump Installation: What to Expect
A day-by-day breakdown of the heat pump installation process from survey to completion.
Wondering what actually happens during a heat pump installation? Here's the complete process explained step by step.
Timeline Overview
Stage 1: Initial Survey (Week 1)
An MCS certified surveyor visits your home to assess suitability. This takes 1-2 hours and includes:
- Heat loss calculation: Room-by-room measurement to determine required heat pump size
- Property inspection: Insulation levels, radiator types and sizes, existing heating system
- Outdoor space assessment: Location for outdoor unit, distance to indoor unit, drainage
- Electrical check: Consumer unit capacity, cable runs required
- Hot water needs: Current cylinder or need for new one, sizing requirements
🔍 What the surveyor will tell you:
- • Whether your home is suitable (most are)
- • Recommended heat pump size (kW rating)
- • Any prep work needed (radiator upgrades, cylinder replacement)
- • Estimated installation timeline
Stage 2: Quote & Grant Application (Week 1-2)
Within a week, you'll receive a detailed quote showing:
- Full installation cost breakdown
- Less £7,500 BUS grant
- Your final payment amount
- Equipment specifications (brand, model, warranty)
- Payment schedule (typically deposit, then balance on completion)
Once you accept, the installer applies for your BUS grant. Ofgem typically approves within 48 hours, issuing a redemption code valid for 3 months.
Stage 3: Pre-Installation Prep (Week 2-4)
Before installation day, you may need:
Some older radiators are too small for heat pump flow temperatures. Installer will replace undersized radiators (typically 2-4 per home). This adds 1 day to timeline and £500-1,500 to cost.
If you have a combi boiler (no cylinder), you'll need a new unvented cylinder installed. Takes half a day, typically £800-1,200 included in quote.
Heat pump needs dedicated circuit from consumer unit. Electrician runs cable to outdoor unit location. Usually done on Day 1 of installation.
Stage 4: Installation Days (Air Source)
Day 1: Outdoor Unit & Electrical
What happens:
- Outdoor heat pump unit delivered and positioned (wall-mounted or ground pad)
- Drilling through wall for refrigerant pipes and cables
- Electrician installs dedicated circuit and wiring
- Condensate drain pipe installed
Your old boiler stays connected and working throughout.
Day 2: Indoor Unit & Pipework
- Indoor heat pump unit installed (usually in garage, utility room, or where boiler was)
- Hot water cylinder installed/connected if needed
- Refrigerant pipes connected between indoor and outdoor units
- System pipework connected to existing radiators
- Buffer tank installed if required (depends on system design)
Day 3: Commissioning & Handover
- System filled, pressurized, and leak-tested
- Heat pump started up and commissioned
- Settings optimized for your home (flow temp, heating schedules)
- Full system demonstration and handover
- Old boiler decommissioned and removed
- MCS certificate issued
Ground Source Installation
Ground source takes longer due to ground loop installation:
Days 1-3: Excavate trenches 1.5m deep across 100-200m² of garden. Lay ground loop pipes in slinky or straight runs. Backfill and restore lawn.
Days 4-5: Indoor heat pump installation and connection to ground loop.
Days 6-7: System fill, commissioning, handover.
Days 1-4: Drilling rig arrives. Drill 1-3 boreholes 50-150m deep. Insert ground loop pipes and grout.
Days 5-7: Indoor unit installation, connection, and manifold setup.
Days 8-10: Pressure testing, commissioning, optimization, and handover.
What to Expect During Installation
Disruption Level
- ✓ You can stay at home throughout
- ✓ No heating/hot water for 4-8 hours max (usually Day 2)
- ✓ Some dust and noise (drilling, pipe work)
- ✓ 2-3 engineers on site each day
- ✓ Ground source: Garden inaccessible for 3-5 days
After Installation
The first few weeks are a "settling in" period:
- Week 1-2:Installer remotely monitors performance and tweaks settings for optimal efficiency.
- Month 1-3:You learn how to use the system. Heat pumps work differently to boilers—leave them running low continuously rather than blasting on/off.
- 6-12 months:First annual service (usually free). Performance check and minor adjustments.
Common Installation Issues (and Solutions)
Solution: Flow temperature too low. Installer adjusts up by 5°C. Most common in first 2 weeks.
Solution: Check anti-vibration mounts installed correctly. Add acoustic fence if needed.
Solution: Usually due to heat-up mode (bringing house to temp from cold). Bills normalize after 2-4 weeks.
Your Checklist
- ☐ EPC up to date with insulation completed
- ☐ BUS grant approved (redemption code received)
- ☐ Clear access to indoor installation location
- ☐ Outdoor unit location agreed and clear
- ☐ Deposit paid, installation dates confirmed