The short version
- The survey gathers what is needed for a room-by-room heat loss calculation: room sizes, wall, floor and roof construction, insulation, windows and draughts.
- MCS’s design standard, MIS 3005-D, says the calculation should follow BS EN 12831-1:2017, and the heat pump chosen must meet at least 100% of the calculated heat load without help from a backup electric heater.
- The surveyor also checks radiators, pipes, hot water, the fuse board and the outdoor unit spot, including an MCS 020(a) sound calculation where the unit is to go in under permitted development in England.
- Afterwards you should get room heat losses, the design flow temperature, radiator sizes, a performance estimate and a clear written quote that lists any extra work.
- The installer applies for the Boiler Upgrade Scheme from the agreed quote. You may be eligible for £7,500.
A survey turns “could a heat pump work here?” into a design you can check, so it is worth knowing what a good one covers and which parts come from MCS standards. For what happens next, see our guide to heat pump installation, step by step.
What happens in a heat pump survey?
Someone walks through every room, takes measurements and photos, and asks how you use your heating and hot water. The point is to collect everything needed to design the system, not just to pick a box size.
MCS requires it. Both versions of MIS 3005-D, the heat pump design standard that MCS certified installers work to, say the installer must make sure the building, “including curtilage” (the land around it), is assessed by a competent professional experienced in heat pump systems. That person checks the home is suitable and that the work will not compromise its compliance with the Building Regulations, in particular on energy efficiency and electrical safety. The Energy Saving Trust’s installer guidance adds that for an existing home “a detailed site survey will be needed”.
The room-by-room heat loss calculation
This is the core of the visit. A room’s heat loss is how much heat it needs to stay warm on a cold day; the total sets the heat pump size. MIS 3005-D says the calculation should use set indoor and outdoor temperatures and otherwise comply with BS EN 12831-1:2017.
| Room | Minimum design temperature (MIS 3005-D Table 1) |
|---|---|
| Living room, dining room, bedsitting room | 21°C |
| Bedroom, hall and landing, kitchen, toilet | 18°C |
| Bathroom | 22°C |
For the outdoor side, the standard lists design temperatures by location. For Manchester it gives −2.7°C (the temperature equalled or exceeded for 99% of the hours in a year) or −4.5°C (99.6%), and the installer chooses which column fits your location. See what size heat pump do I need? for how these figures turn into a kilowatt rating.
The Energy Saving Trust’s installer toolkit lists what a surveyor records:
- Walls: external, internal and party wall construction, and any insulation added over the years.
- Lofts and roofs: the thickness of loft insulation and the type of roof.
- Floors: which rooms are on the ground floor and whether the floor is solid or suspended. MIS 3005-D treats the two differently in the calculation.
- Windows and doors: their condition, frame material, glazing and age.
- Draughts and ventilation: open fireplaces, vents and gaps all add to the heat a room loses.
- What is next door: whether each room has a heated room above or below, a loft, or an unheated space such as a porch or conservatory alongside.
The same guidance notes that in-situ U-values (how well your actual walls and floors hold in heat) and airtightness can vary considerably, which is why the surveyor asks questions. If you know what was done to the house and when, say so.
Radiators, pipework and your existing heating
A heat pump is most efficient when it heats water to a lower temperature than a typical boiler, so radiators may need to be bigger to give out the same heat. The surveyor notes the type and size of every radiator or other emitter and, according to the Energy Saving Trust toolkit, the space available in case a larger radiator is needed. Our guide do I need new radiators for a heat pump? explains how that comparison works.
They will also check pipe sizes, because a heat pump moves water at higher flow rates, and how new pipes will enter the building and join the existing system. The lower the flow temperature, the more efficiently the system runs; see heat pump flow temperature explained.
If a design proposes a flow temperature above 55°C, MIS 3005-D says the installer should also give you an alternative design at 55°C or lower, explain the differences in efficiency and energy use, and let you choose.
Hot water
The surveyor will ask how many people live in the home and count the bedrooms. For homes, MIS 3005-D works out the daily hot water demand with the formula 45 × N, where N is the larger of the number of bedrooms plus one, or the number of known occupants.
They will also note any existing cylinder’s position, type and size, and your mains water supply. Where the design uses a cylinder, the standard says it should be sized from the daily demand, and an existing cylinder that is kept must have its insulation brought up to the level required for new installations. Ask the surveyor to explain in writing how your hot water will be provided. Our guide to heat pumps and hot water covers the options.
Where the outdoor unit goes, and the noise check
In England, an outdoor unit can often go in under permitted development rights, and one of the conditions is the MCS 020(a) sound calculation. The Energy Saving Trust toolkit advises doing it early, so the system is designed around a suitable location.
MCS 020(a) checks whether the unit would meet a limit of 37 dB(A) at an “assessment position”: a point 1 metre outside the centre of a door or window to a habitable room of a neighbouring property. To work it out, the installer:
- takes the unit’s sound power level from the manufacturer’s data, and may not use the figure for “low noise mode”;
- counts the reflecting surfaces, such as the ground and nearby walls, within 1 metre of the unit. A position with more than three, such as a small lightwell, will not meet the standard;
- measures the distance to each assessment position to the nearest 0.1 metre;
- allows for any solid wall or fence between the unit and the neighbour’s window.
The standard says the installer must keep one copy of the completed calculation and give another to you. Other planning conditions apply too, and Wales has its own rules; see do you need planning permission for a heat pump? and are heat pumps noisy?
Your electrical supply
Expect the surveyor to look at your fuse board and the main incoming fuse, and whether there is room for any extra consumer unit. MIS 3005-D says the installer must make sure the electricity supply is adequate for the size of heat pump specified, and that the installation is notified to your Distribution Network Operator (the company that runs the local power network), with permission sought in advance where necessary.
How long does a heat pump survey take?
There is no set length in the MCS standards; it depends on the size and complexity of the home. A small, simple flat takes less time than a large older house with extensions. When you book, ask how long to allow so you can be in for the whole visit.
MCS is moving installers from its original scheme onto a redeveloped one (MCS:2025) in phases through 2026 and into 2027, so two versions of MIS 3005-D are in use. The original-scheme version (Issue 3.0) says the design should be complete within 60 calendar days of the contract being agreed. The MCS:2025 version (Issue 2.0) does not repeat that clause, so ask what timescale your installer works to.
What you should get after the survey
What you are promised before you sign depends on which MCS scheme your installer is on, so ask. For installers already on the redeveloped MCS:2025 scheme, its Customer Commitment says the installer will give you a clear and detailed written quotation, tell you about any additional work needed and its cost at the quotation stage, explain how any grant is applied to the cost, and provide realistic estimates of how the system is likely to perform. The contract should state the product’s make, model number and power rating. For installers still on the original scheme, MIS 3005-D Issue 3.0 says a performance estimate and the manufacturer’s datasheet for the proposed heat pump must be given to you in writing before the contract is awarded.
Before installation starts, MIS 3005-D lists the design information to be provided in writing:
| Design document | Why it matters to you |
|---|---|
| Specific heat loss of every room (W/m²) | Shows the survey was done room by room |
| Calculated daily hot water demand | Shows how your household’s hot water use was sized |
| Type and dimensions of each radiator or emitter | Tells you which radiators change |
| Design emitter temperature, based on the worst-performing room | The room that sets the water temperature |
| Specification and recovery rate of any new hot water cylinder | How quickly hot water comes back |
| Design flow temperature leaving the heat pump | Lower usually means a more efficient system |
| The installation’s SCOP at that flow temperature | A comparable efficiency figure |
| Any metering that may be needed for financial incentives | Avoids surprises later |
One detail is worth knowing. The original version of MIS 3005-D says this list goes to you; the redeveloped MCS:2025 version says it goes to the installer. Either way, ask for a copy. If the detailed design changes what you were quoted, the MCS:2025 Customer Commitment says you must get a written variation to the contract, and if the change is significant you can choose to carry on or cancel without further cost. To weigh up more than one quote, see how to compare heat pump quotes.
The cost depends on what the survey finds: the heat pump size, any radiator or pipework upgrades, where the outdoor unit goes and the pipe run, hot water and any electrical work. See heat pump costs in Manchester.
How to prepare for a heat pump survey
MCS’s Customer Commitment for its redeveloped scheme asks customers to give accurate information about how many people live in the home, what insulation they have, any future home improvements and how they are likely to use energy. To prepare:
- Clear access to the loft hatch, the airing or cylinder cupboard, the boiler and the fuse board.
- Find any paperwork on insulation, new windows, extensions or a floor plan from when you bought the house.
- Have a recent energy bill to hand showing your annual gas, oil or electricity use.
- Note any rooms you keep warmer or cooler than usual, and plans to extend or insulate.
- Have a view on where you would and would not want the outdoor unit and any cylinder.
How the survey links to the Boiler Upgrade Scheme
The Boiler Upgrade Scheme offers £7,500 towards an air source heat pump in England and Wales. You may be eligible if you own the property and are replacing fossil fuel heating such as gas, oil, LPG or electric. Social housing and most new builds are not eligible, and hybrid systems are not covered.
GOV.UK sets out the order: get quotes from MCS certified installers, confirm eligibility (your installer will tell you), agree a quote, and the installer applies to Ofgem for you. The grant comes off what you pay, and Ofgem will contact you to confirm the installer is acting for you.
So the grant application rests on a quote built from the survey. Under the scheme regulations, a voucher for an air source heat pump expires three months after it is issued, so the installation needs to be ready to go. More on eligibility is on our grants and rebates page.
What to ask, and where ByEco stands
Whoever surveys your home, these questions will tell you a lot:
- Will you do a room-by-room heat loss calculation, and can I have the results?
- What design flow temperature are you aiming for, and which radiators would change?
- Where would the outdoor unit go, and can I see the MCS 020(a) calculation?
- How will my hot water be provided?
- What would make the final design differ from this quote?
We are MCS certified for air source heat pump installation (certificate IAA10330), and we apply for the £7,500 Boiler Upgrade Scheme grant on your behalf. Get in touch for a free home survey: we will work through your home room by room, explain what your system needs and give you an itemised quote. If you are happy with it, we go ahead. Find out more about our air source heat pump service or book a free survey.
Sources
Every figure on this page was checked against primary sources on 29 October 2026. Grant rules, planning rules and prices change — if you are reading this much later, verify before acting.
- MCS — MIS 3005-D:2025 Heat Pump Design Standard, Issue 2.0 (5 December 2025)
- MCS — MIS 3005-D The Heat Pump Design Standard, Issue 3.0 (5 December 2025)
- MCS — MCS 020(a) Air source heat pump sound calculation, Issue 1.1
- MCS — Customer Commitment, MCS:2025 2.0, Issue 1.1 (8 September 2026)
- MCS — Transitioning to the redeveloped installer Scheme
- Energy Saving Trust — Heat pump installer toolkit: heat loss calculations, detailed guidance
- GOV.UK — Apply for the Boiler Upgrade Scheme: how to apply
- GOV.UK — Apply for the Boiler Upgrade Scheme: what you can get
- GOV.UK — Apply for the Boiler Upgrade Scheme: check if you’re eligible
- legislation.gov.uk — The Boiler Upgrade Scheme (England and Wales) Regulations 2022, regulation 15
Book your free home survey
Every home is different. The cost depends on the size of system, any radiators that need upgrading, the pipework and where the outdoor unit goes. Get in touch and we will arrange a free survey of your home and give you a clear quote. If you are happy with it, we can go ahead.
