Answer first
In the government-funded Electrification of Heat project, installations averaged two to four days with two installers and an electrician. That included new radiators and water tanks but excluded energy-efficiency work.
Treat that as evidence from one large project, not a promise. A simple installation can be shorter; a large home, major pipe replacement, difficult routes or separate fabric work can take longer. Ask when heating and hot water will be unavailable and how the team will manage it.
Average installation duration in the 742-home demonstration project
View sourceTypical project team in that reported average
View sourceElectrical work formed part of the reported installation team
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The installation starts before anyone removes the boiler
Design, funding steps, equipment ordering, DNO notification or approval, planning checks and scheduling all happen before the physical work. Delays in that preparation do not count as days in the home, but they affect the calendar date.
Do not authorise removal of working heating until the equipment, design and dependencies are ready. The installer should confirm any customer actions, funding conditions and access requirements in advance.
What happens during the main works
The sequence varies, but work can include removing the old boiler or tank, installing the outdoor unit and base, fitting a cylinder, changing radiators, adapting pipework, adding electrical circuits, routing condensate, filling and flushing, then controls and commissioning.
Different trades may overlap. A well-planned programme shows who attends on each day and when the home will lose heating, hot water, electricity or water.
- 1
Protect and isolate
Agree access, floor protection, shutdowns and what old equipment will be removed.
- 2
Install equipment and distribution changes
Outdoor unit, cylinder, emitters, pipework and electrical work are coordinated.
- 3
Commission the system
Flow, balancing, controls, hot water, safety and design settings are checked.
- 4
Handover
The homeowner receives controls guidance, documents, warranty and support contacts.
What makes an installation longer
Replacing many radiators is repetitive but predictable. New pipe routes, solid floors, asbestos, restricted lofts, listed-building requirements, scaffold, wall repair or an electrical supply upgrade can add more uncertainty.
Separate insulation or building work should have its own programme. The two-to-four-day demonstration-project average specifically excluded energy-efficiency measures, so it should not be applied to a combined retrofit without adjustment.
- Number and accessibility of radiator changes
- Cylinder relocation or cupboard alterations
- Microbore replacement and floor access
- Long external or internal pipe routes
- Consumer-unit or network work
- Planning, scaffold or specialist building work
Plan for the time without heating and hot water
Energy Systems Catapult highlighted the importance of explaining disruption early and providing an alternative heat source during the installation period. Ask exactly which services will be unavailable, for how long and what contingency applies if commissioning slips.
Protect anyone who needs dependable warmth or hot water. Medical needs, young children, home working and pets can change the sensible schedule.
Completion is more than switching it on
Allow time for balancing, weather-compensation settings, hot-water programming and a proper homeowner handover. A rushed handover can leave an efficient system operating badly because the occupants do not understand setbacks, boost settings or what a normal defrost looks like.
Before final payment, agree any snagging, documentation and monitoring check. Take photos of settings and ask who to contact if comfort or consumption is not as expected.
What to read next
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Questions people also ask
Will I be without heating for the whole installation?+
Not always, but there will normally be a period when the old system is isolated. The installer should state the expected outage and contingency before work.
Can I stay in the house?+
Often yes, although noise, access and service interruptions can be disruptive. Discuss household needs and safe working areas when planning the job.
Does the quoted duration include insulation?+
Do not assume so. The cited two-to-four-day project average excluded energy-efficiency work. Ask for each workstream and dependency in the programme.
Evidence used for this answer
Figures are explained in context and links go to the independent source. Prices, tariffs, scheme rules and standards can change, so check the source again before making a financial or technical decision.
- Energy Systems Catapult: home surveys and installation reportEvidence from 742 installations, including radiators, cylinders, survey constraints and typical installation duration.
- MCS domestic heat-pump guideConsumer guidance covering design, installation, controls, handover and maintenance.
- MCS heat-pump design standardTechnical requirements for heat loss, equipment selection, domestic hot water and system design.