Heat pump installation planning: survey, design and handover

Prepare a survey evidence pack

Collect floor plans or measured room dimensions, construction and insulation notes, window and door sizes, ventilation details, an EPC, recent energy bills, current radiator dimensions, hot-water use and known comfort problems. Bills and an EPC provide context, but neither replaces a room-by-room design heat-loss calculation. Tell the surveyor about planned extensions, insulation or occupancy changes so the design does not freeze an outdated version of the home.

The survey record should state indoor design temperatures, local external design condition, fabric assumptions, air-change assumptions and a heat loss for each room as well as the building total. Uncertain construction should be marked as an assumption or investigated. Ask for the report before committing, because it is the bridge between the property evidence, selected heat-pump output and emitter schedule.

Connect heat loss, equipment output and emitters

The exact model must supply the required heat at the proposed outdoor and flow temperatures, not merely match a large number in a brochure heading. Ask the designer to show capacity at design conditions, proposed flow temperature, defrost and backup assumptions, system volume and control strategy. Oversizing can affect cycling and cost; undersizing can compromise comfort or lean too heavily on backup heat.

Existing radiators are not automatically unsuitable. For every room, compare design heat loss with the output of the proposed radiator, fan convector or underfloor loop at the intended mean water temperature. Record which emitters stay, which change and why. If a higher flow temperature is proposed to avoid radiator work, ask how it changes the seasonal-performance estimate and whether comfort is still demonstrated at the cold design condition.

Design hot water as a separate service

A standard air-to-water heat pump normally heats stored water rather than producing hot water instantly like a combi boiler. The proposal should identify cylinder type and volume, available cupboard space, coil compatibility, expected reheat strategy, target temperatures, immersion or other backup, controls and how the household's peak use was assessed. Pipe losses and cylinder placement should be visible rather than left as an afterthought.

Most air-to-air systems heat or cool rooms but do not provide domestic hot water, so a separate solution and its running cost are needed. Do not compare air-to-air and air-to-water totals until both options deliver the services the household requires. Any legionella-control or high-temperature cycle must be described by the competent designer and manufacturer instructions, not improvised from generic online advice.

Allocate electrical and refrigerant responsibilities

The quotation should say who checks the incoming supply, designs the dedicated circuit and protection, completes electrical work and supplies the relevant certification. It should also state who handles Distribution Network Operator notification or connection permission where required. Do not assume a consumer unit, cable route or existing supply is adequate until it has been assessed.

Split systems and any work that opens a refrigerant circuit require the applicable refrigerant competence and, where fluorinated gas is involved, the qualifications and company certification required by law. Ask for the responsible business and evidence before work starts. Homeowners should never be directed to open, charge or alter a refrigerant circuit themselves. A monobloc layout does not remove the need for competent electrical, hydraulic and commissioning work.

Resolve outdoor siting, water, noise and permission

Mark the exact outdoor-unit position, dimensions, service and airflow clearances, pipe route, mounting or base, condensate and defrost-water route, access for maintenance and exposure to damage. A narrow corner may look convenient but can change airflow, reflected sound and service access. Ask for the manufacturer's normal operating sound-power evidence and the site calculation; sound pressure at an unspecified distance is not a substitute.

Planning rules vary by nation, property and local restriction. England's permitted-development route has conditions and an MCS sound assessment; listed buildings, designated land, flats, leasehold terms, Article 4 directions and planning conditions may create separate questions. Freeholder or landlord consent is not replaced by planning permission. Confirm the route with the relevant authority and record who is responsible for applications or evidence before ordering equipment.

Make the quotation an installation schedule

A comparable quote names the exact heat pump, cylinder, emitters and controls and attaches the design outputs that justify them. It should allocate pipework, insulation, valves, pumps, buffer or low-loss components where used, water treatment, outdoor works, drainage, scaffolding, removal, waste, making good, electrical work, network notifications, building-control route, planning evidence, commissioning, training, warranty and aftercare. List exclusions and provisional sums plainly.

Keep project price before grant, the scheme contribution, genuine commercial discounts and customer payment separate. Link milestones to defined deliverables, not only dates. Establish who owns design errors, who coordinates subcontractors, how variations are approved and what happens if permissions, supply capacity or hidden fabric conditions alter the scope. The lowest number is not comparable if it transfers unresolved work to the homeowner.

Witness commissioning and collect the handover pack

Commissioning should confirm that the installed system matches the design, is filled and treated as specified, has suitable flow, is balanced, has working safety devices, controls and sensors, and is configured for the intended weather compensation, hot water and backup strategy. Ask the installer to demonstrate normal operation, schedules, fault indicators, frost protection and the safe customer checks. Do not accept an efficiency promise based only on a factory default screen.

Retain commissioning sheets, heat-loss and performance calculations, equipment list and serials, control settings, user manuals, warranty registration, maintenance schedule, electrical certificates, planning or permitted-development evidence, building-control and network records where applicable, refrigerant records where applicable and the MCS certificate for an MCS installation. Record the support contact and response process. Photograph labels and agreed settings before the installer leaves.

Plan the first season and aftercare

Agree when the installer will review the system after occupants have used it in real weather. Track comfort, flow temperature, hot-water recovery, backup operation and electricity consumption without repeatedly changing several settings at once. A high first bill is a reason to inspect tariff, weather, demand, controls and system behaviour; it is not by itself proof of a product fault or a guaranteed design failure.

Maintenance should follow the manufacturer and handover schedule. Keep outdoor airflow clear and use only the safe homeowner checks explained at handover. Refrigerant, sealed electrical and specialist hydraulic work belongs with qualified people. Preserve the original design and commissioning records so a future engineer can distinguish a changed household pattern from a changed system condition.

Decision checklist

Frequently asked questions