How We Survey, Design and Install Your Air Source Heat Pump

An efficient heat pump installation starts long before the equipment arrives.

At Enerus, we take a design-first approach. We survey the property, calculate its room-by-room heat loss, assess the existing heating system and plan how every part of the new system will work together. Only then do we specify the heat pump, cylinder, radiators, controls and installation requirements.

This detailed preparation helps us design a system that can keep your home comfortable at the local winter design temperature while operating at the lowest practical flow temperature. It also gives you a clear explanation of the proposed system before you commit to the installation.

Your heat pump journey with Enerus
Initial consultation
On-site technical survey
Room-by-room heat-loss calculations
Complete system design and proposal
Professional installation
Testing and commissioning
Customer handover
Aftercare and first-winter support

Why heat pump design matters

A heat pump is not simply a replacement boiler with a different fuel source. It normally works most efficiently by supplying steady, lower-temperature heat for longer periods. The heat pump, radiators or underfloor heating, hot-water cylinder, controls and pipework must therefore be designed as one complete system.

Selecting equipment from the number of bedrooms or the output of the old boiler is not enough. The design must answer several important questions:

How much heat does the property lose on a cold winter day?
How much heat does each individual room require?
What flow temperature is needed to keep every room comfortable?
Can the existing radiators provide enough heat at that temperature?
What heat-pump capacity is available at the property’s outdoor design temperature?
How much stored hot water does the household need?
Where can the outdoor unit and cylinder be installed safely and practically?
Will the proposed location meet applicable noise and planning requirements?

Current MCS heat-pump design standards require room-level heat-loss information, emitter specifications, the proposed design flow temperature, cylinder information and a system performance estimate to be established before installation. Our process is built around getting these fundamentals right.

Step 1: Your initial consultation

Your journey starts with a straightforward conversation about your home and what you want from the new heating system.

We will ask about your current heating, energy use, comfort, hot-water requirements and any renovation or insulation work you are planning. We will also explain how a heat pump differs from a conventional boiler, what the installation may involve and how the Boiler Upgrade Scheme may apply to an eligible project.

At this stage, we can discuss likely installation and running-cost considerations. However, we will not pretend that an accurate fixed design can be produced from a telephone call alone. A firm specification requires an on-site technical survey and detailed calculations.

Step 2: The on-site technical survey

An Enerus engineer will visit the property to collect the information needed for the design. A typical domestic survey takes approximately 1.5 to 2 hours, although larger or more complex homes can take longer.

The survey is not limited to measuring rooms. We assess the property as a complete heating system.

Building fabric

We record relevant details including:

room dimensions and ceiling heights;
external walls and their likely construction;
floors, roofs and adjoining heated or unheated spaces;
window and external-door dimensions and glazing types;
loft, wall and floor insulation where it can be established;
ventilation provisions and other significant heat-loss routes; and
any planned building improvements that may affect the final design.

Existing heating and hot water

We also examine:

the existing boiler or heating appliance;
radiator sizes and types in each room;
underfloor-heating areas, where present;
visible pipework and likely distribution arrangements;
the hot-water cylinder and available storage space;
current controls and heating zones; and
how the household uses heating and hot water.

Proposed equipment locations

The survey includes practical planning for:

the outdoor heat-pump position and required clearances;
noise assessment and proximity to neighbouring properties;
a safe condensate discharge route;
cylinder, control and ancillary-equipment locations;
new pipework routes and insulation;
electrical supply and cable routes;
installation access; and
any planning, electrical-network or structural considerations identified at survey stage.

Where something cannot be confirmed during the initial visit, we will identify what further investigation is needed rather than building the design around an assumption.

Step 3: Room-by-room heat-loss calculations

Back at the office, the survey information is entered into professional design software. Each room is calculated separately using its dimensions, construction, exposed surfaces, glazing, ventilation and target internal temperature.

The calculations establish:

the heat loss of every room;
the total design heat load of the property;
the output required from each radiator or underfloor-heating zone; and
the lowest practical system flow temperature that can maintain comfort.

This work follows recognised heat-loss methodology and the applicable MCS design requirements. It is deliberately more detailed than estimating heat demand from floor area, historic fuel consumption or the size of the existing boiler.

If you only require an independent calculation rather than a complete installation, see our professional heat-loss survey service.

Step 4: Designing the complete heat-pump system

Once the heat losses are established, we design the complete system around the building and the way it will be used.

Heat-pump selection

We assess the manufacturer’s published output at the proposed flow temperature and the outdoor design temperature for the property. The number printed on the front of a heat pump is not enough: its available output changes with operating conditions.

For a full heat-pump system, the selected unit must be capable of meeting the calculated design heat load without relying on a supplementary electric heater to disguise undersizing.

Radiators and underfloor heating

Every emitter is checked against the heat required by its room at the proposed flow temperature. Existing radiators that are suitable can remain. Where an emitter cannot provide enough output, the design will identify the upgrade required.

This does not mean replacing every radiator automatically. The objective is to create a balanced low-temperature system—not to sell unnecessary equipment.

Hot-water design

We calculate the household’s expected daily hot-water demand and specify a suitable heat-pump cylinder and recovery arrangement. Available space, occupancy, bathroom use and the heat pump’s hot-water capability are considered together.

Controls and hydraulic design

The design also covers the system layout, water flow requirements, circulation, controls, weather compensation and any buffer or volumiser required by the selected equipment. Good hydraulic design helps the heat pump maintain stable flow and operate as intended.

Performance estimate

You will receive an estimate of the proposed system’s annual performance and electricity consumption using the prescribed methodology and the information available at design stage. This is an informed estimate, not a guaranteed energy bill. Weather, electricity tariffs, occupancy, thermostat settings and how the system is operated will all affect actual consumption.

Step 5: Your installation design pack and fixed proposal

We bring the survey, calculations and system specification together in an Installation Design Pack and Contract. The exact length varies with the project, but it provides a clear written record of what has been designed and what is included.

Your pack will normally cover:

room-by-room and whole-property heat loss;
selected heat pump and relevant design output;
proposed design flow temperature;
radiator or emitter schedule;
hot-water cylinder specification;
proposed equipment locations;
noise and planning assessment where applicable;
estimated seasonal performance and electricity use;
installation scope and exclusions;
fixed quotation and payment schedule; and
contract terms, warranties and customer responsibilities.

We will explain the proposal and answer your questions before an installation date is agreed. If a design choice involves a trade-off—such as retaining smaller radiators and using a higher flow temperature—we will make that clear.

Step 6: Preparing for installation

Before work starts, we confirm the equipment, installation programme and access arrangements. Where required, the electrical network connection process, planning checks, grant application and product registrations are progressed at the appropriate stage.

You will know where the outdoor unit, cylinder and internal equipment are intended to go, which radiators are being changed, the planned pipe routes and how long the work is expected to take.

Step 7: Professional installation

On the first morning, the installation team will review the agreed design and walk through the work with you before starting. Floors and working areas are protected, materials are checked and the planned locations and pipe routes are confirmed.

The installation may include:

removal or safe isolation of the existing heat source;
installation of the outdoor heat pump;
hot-water cylinder and hydraulic components;
heating pipework and insulation;
radiator or underfloor-heating upgrades;
electrical supplies and controls;
condensate drainage; and
system cleaning, filling and water treatment.

We work to the approved design and manufacturer instructions. If an unexpected site condition requires a material change, it will be discussed and recorded rather than improvised without explanation.

Once the physical work is complete, exposed new pipework is insulated where required, work areas are cleaned and the property is left ready for commissioning.

Step 8: Testing and commissioning

Commissioning is more than switching the heat pump on. The system is checked, tested and adjusted so it operates in line with the design.

Depending on the system, this includes checking:

system pressure, water flow and circulation;
electrical supplies and protective devices;
sensors and control settings;
heating-curve and weather-compensation settings;
flow and return temperatures;
domestic-hot-water operation;
frost protection and condensate drainage;
system cleanliness and water treatment;
outdoor-unit clearances and vibration control; and
recorded operating data required for the commissioning documentation.

Fine-tuning continues during handover and, where necessary, through seasonal aftercare. A heat pump commissioned during mild weather may still benefit from adjustment when the heating system experiences genuine winter conditions.

Step 9: Customer handover

Before we leave, we demonstrate how to use the heating and hot-water system. We explain the controls, normal operating behaviour, recommended settings and what to do if something does not appear right.

Your handover information will include the relevant documents for the installation, such as:

as-installed system information;
commissioning records;
product manuals;
warranty registrations;
MCS installation certification;
electrical and Building Regulations documentation where applicable;
grant-related records where applicable; and
servicing and maintenance requirements.

The aim is for you to understand the system—not to leave you with a folder of unexplained paperwork.

Step 10: Aftercare and first-winter support

Our responsibility does not end when the installation team leaves.

Enerus provides a 24-month workmanship warranty on its heat-pump installations. If you need assistance, contact us by phone or email with a description of the issue, when it started and whether anyone has altered the heating system since installation. We can then assess the information and arrange an engineer visit when required.

We also offer a complimentary first-winter visit to check how the system is operating under colder conditions. This gives us an opportunity to review settings, answer questions and make appropriate adjustments where needed.

Annual servicing is important for reliability and may be required to maintain the manufacturer’s warranty. Enerus services and repairs heat pumps installed by us and systems installed by other companies. Visit our heating-system servicing and repair page for more information.

Start with a properly designed system

A high-quality heat pump installation is the result of accurate information, careful design, competent installation and thorough commissioning. Skipping any of those stages can affect comfort, efficiency and long-term reliability.

Enerus provides a single, accountable route from the initial conversation through to survey, design, installation and aftercare.

Book your free initial heat-pump consultation.

Call 01740 669 585, email homeservices@enerus.co.uk or contact Enerus online.

Frequently asked questions

How long does an air source heat pump survey take?

Most domestic technical surveys take around 1.5 to 2 hours. Large, extended or unusually constructed properties may require longer or a follow-up investigation.

Will every radiator need replacing?

No. Each existing radiator is checked against the room’s calculated heat loss and the proposed flow temperature. Suitable radiators can remain; only emitters that cannot provide the required output need to be addressed.

Why can you not give an exact quotation over the phone?

The final equipment, radiator upgrades, cylinder, electrical work and installation requirements depend on the property. A telephone estimate cannot replace an on-site survey and completed system design.

Does the survey include a heat-pump noise assessment?

The proposed outdoor-unit position is considered during the survey. Where applicable, the design includes the noise assessment required for the proposed planning route and MCS requirements.

Is the performance estimate guaranteed?

No. It is a design-stage estimate based on calculated demand, equipment data and standard assumptions. Actual electricity use is affected by weather, tariffs, occupancy, control settings, hot-water use and user behaviour.

What happens after my heat pump is installed?

The system is commissioned and demonstrated, and the relevant installation documents and registrations are completed. Enerus also provides aftercare, a 24-month workmanship warranty, a complimentary first-winter visit and ongoing servicing options.

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Heat Pump Survey, Design and Installation Process