Home Heat Pump Guide

How to Prepare Your Home for a Heat Pump

A heat pump will work best — and cost the least to run — when your home is properly prepared for one. The good news is that preparation does not have to be complicated or expensive. Most of it is practical common sense, and much of it will reduce your energy bills regardless of what heating system you use.

This guide walks you through everything you should do before your heat pump installation day, from insulation upgrades to clearing outdoor space, checking your radiators, and getting your paperwork in order.

Step 1: Improve Your Insulation

This is the single most impactful thing you can do. Heat pumps deliver heat at lower temperatures than gas boilers — typically 35–50°C compared to 60–80°C. That means your home needs to retain heat more effectively. The better your insulation, the lower the heat pump can run its flow temperature, and the higher its efficiency.

Loft Insulation

If your loft insulation is less than 270mm deep (the current Building Regulations recommendation), top it up. This is one of the cheapest and most effective upgrades you can make. Costs are typically £300–£600 for a standard three-bedroom house, and it can reduce heat loss through the roof by up to 25%.

If your loft is already at or above 270mm, no further action is needed.

Cavity Wall Insulation

If your home was built between the 1930s and 1990s, it likely has cavity walls. If the cavities are unfilled, getting them insulated costs around £500–£1,500 and makes a significant difference. You can check whether your cavities are filled by looking for drill holes in the exterior mortar or asking a surveyor.

If your home has solid walls (typically pre-1930s), the options are internal or external wall insulation — both more expensive (£5,000–£15,000) but potentially worthwhile, especially if your heat pump running costs would otherwise be high.

Floor Insulation

Suspended timber floors can be insulated from below if there is access to the void. Solid concrete floors are harder to insulate retrospectively. If you are already planning building work, it is worth considering, but floor insulation alone should not hold up a heat pump installation.

Windows and Doors

Double glazing is sufficient for most heat pump installations. If you still have single-glazed windows, upgrading to double glazing will reduce heat loss significantly. Triple glazing is beneficial but not essential — the cost-benefit is marginal compared to loft and wall insulation.

Draughtproofing around doors, windows, letterboxes, and other gaps is cheap and effective. A draughtproofing kit for the whole house might cost £50–£200 and can make a noticeable difference.

Step 2: Get an EPC (Energy Performance Certificate)

An EPC rates your home's energy efficiency from A (most efficient) to G (least efficient). You will need one for several reasons:

  • BUS grant requirement: To claim the Boiler Upgrade Scheme grant of £7,500, your home must have a valid EPC. There is no minimum rating required, but having one is mandatory.
  • Identifies improvements: The EPC report lists recommended upgrades with estimated costs and savings — useful for prioritising preparation work.
  • Installer reference: Your MCS installer will use the EPC data alongside their own survey to design the heat pump system correctly.

An EPC costs around £60–£120 and is valid for 10 years. If you already have one that has not expired, you do not need a new one — though if it was done before recent insulation improvements, a fresh one will give a more accurate picture.

Step 3: Check Your Radiators

Because heat pumps run at lower flow temperatures, your existing radiators may need to work harder — or be upgraded — to deliver enough heat. This does not mean every radiator needs replacing, but it does need checking.

What Your Installer Will Assess

During the survey, your installer will carry out a room-by-room heat loss calculation and compare it against the output your existing radiators can deliver at lower flow temperatures. The key question is: can each radiator provide enough heat at 45–50°C flow temperature to keep that room at the desired temperature?

Common outcomes:

  • Well-insulated home with modern double-panel convector radiators: Existing radiators may be perfectly adequate, perhaps with one or two upgrades in the coldest rooms
  • Older home with small single-panel radiators: Several radiators may need replacing with larger ones
  • Rooms with underfloor heating: Already ideal for heat pumps — no changes needed

Do not pre-emptively replace all your radiators before speaking to an installer. Let the survey dictate what is needed. You might spend money unnecessarily.

Step 4: Clear Outdoor Space for the Unit

An air source heat pump needs an outdoor unit, and that unit needs proper airflow, accessibility, and positioning. Before your installer visits, think about where the unit could go:

Space Requirements

  • The unit itself is roughly the size of a large suitcase to a washing machine, depending on the model and capacity
  • It needs at least 300mm clearance on all sides (more on the fan discharge side — typically 1 metre or more)
  • It should be on a solid, level base — either a concrete pad or purpose-built mounting brackets

Positioning Considerations

  • Noise: Position away from neighbouring bedroom windows. The 42 dB boundary limit must be met.
  • Airflow: Do not box the unit into a tight corner or surround it with dense vegetation. It draws air across a heat exchanger and needs free airflow.
  • Pipework runs: The unit needs to connect to your indoor heating system via insulated pipework. Shorter pipe runs are more efficient and cheaper to install.
  • Access: Leave space for annual servicing and maintenance.
  • Drainage: Heat pumps produce condensate (like an air conditioning unit). You need a suitable drain point nearby.

Before installation day, clear the chosen area of garden furniture, plants, stored items, and debris. If a concrete base is needed, your installer will usually arrange this as part of the installation.

Step 5: Review Your Electrical Supply

Heat pumps run on electricity, and larger units can draw significant power. Your installer will check your electrical supply, but it helps to be aware of potential issues:

  • Main fuse rating: Older homes may have a 60A fuse, which might need upgrading to 80A or 100A. This is done by your DNO (Distribution Network Operator) and is usually free.
  • Consumer unit: You may need a new circuit and MCB (miniature circuit breaker) for the heat pump. If your consumer unit is very old, it might need replacing — typically £300–£600.
  • Three-phase supply: Larger heat pumps (above about 12 kW) may need a three-phase supply. This is more common in larger detached properties.

Your installer will handle the DNO notification if one is required. The key thing is not to be surprised if your electrical supply needs some attention — it is a routine part of the process.

Step 6: Consider Your Hot Water Setup

Most heat pump installations include a hot water cylinder, because heat pumps cannot produce instant hot water the way a combi boiler does. If you currently have a combi boiler and no cylinder, you will need to find space for one.

A typical heat pump hot water cylinder is 170–250 litres and stands roughly 1.5–1.8 metres tall with a diameter of about 55–60cm. Common locations include:

  • Airing cupboard (if large enough)
  • Utility room
  • Garage
  • Under-stairs cupboard (height may be an issue)

If you already have a hot water cylinder from a previous system (system boiler or gravity-fed), it may be possible to reuse the existing space, though the cylinder itself will usually be replaced with a purpose-designed heat pump cylinder with a larger coil for efficient heat transfer.

Step 7: Choose Your Installer Carefully

Preparation is not just physical — choosing the right installer is arguably the most important step. A good installer will guide you through all the preparation above, carry out a thorough survey, and design a system tailored to your home.

Key things to look for:

  • MCS certification: Essential for the BUS grant and a mark of competence
  • Experience: Ask how many heat pumps they have installed, and request references
  • Full survey: Any installer who quotes without visiting your home is a red flag
  • Room-by-room heat loss calculation: This should be standard practice, not optional

Get at least three quotes and compare them carefully. The cheapest is not always the best — and an installer who recommends preparation work (like insulation upgrades) before quoting a smaller, cheaper heat pump is often giving you better advice than one who quotes a large, expensive unit to compensate for poor insulation.

Step 8: Understand the Timeline

A typical heat pump installation process looks like this:

  1. Initial enquiry and quotes: 2–4 weeks
  2. Survey and system design: 1–2 weeks
  3. DNO notification (if needed): 1–4 weeks
  4. BUS grant application: Usually processed within a few weeks
  5. Equipment ordering and scheduling: 2–6 weeks
  6. Installation: 2–5 days on site
  7. Commissioning and handover: Included in installation

From first enquiry to warm radiators, expect roughly 8–16 weeks. Starting your preparation work early — especially insulation improvements — means everything is ready when the installer is.

What Not to Do

Some common mistakes to avoid during the preparation stage:

  • Do not replace all radiators before the survey. Let your installer tell you which ones need upgrading. You might waste money on unnecessary replacements.
  • Do not choose a heat pump model yourself. Your installer will select the right unit based on your home's heat loss calculation. Choosing by brand reputation alone can lead to oversizing or undersizing.
  • Do not skip insulation upgrades to save money. Under-insulating your home means the heat pump works harder, runs less efficiently, and costs more to operate every single year.
  • Do not leave preparation until the last minute. Insulation work, EPC assessments, and electrical upgrades all take time. Starting early keeps the installation on schedule.

Frequently Asked Questions

Do I need to insulate my home before getting a heat pump?

You should ensure your home is reasonably well insulated, but you do not need to achieve Passivhaus standards. At minimum, ensure your loft is insulated to 270mm and cavity walls are filled (if applicable). Your installer will advise on whether further improvements are needed based on the heat loss calculation.

Can I prepare my home while living in it?

Yes, absolutely. All preparation work — insulation, EPC assessment, radiator checks, clearing outdoor space — can be done while you live in the property. The heat pump installation itself typically takes 2–5 days, during which your existing heating continues to work until the switchover.

How much does home preparation cost?

It varies enormously. If your home already has good insulation, double glazing, and adequate radiators, preparation might cost nothing beyond the EPC. If significant insulation work is needed, budget £500–£5,000 depending on what is required. Your installer and the EPC report will help you prioritise.

Do I need an EPC to get a heat pump?

You need an EPC to claim the BUS grant. There is no minimum EPC rating required — even homes rated D, E, F, or G can get the grant. You can install a heat pump without an EPC if you are not claiming the grant, but having one is still useful for the installer's design process.

What if I have a combi boiler and no hot water cylinder?

You will need to find space for a hot water cylinder. This is one of the most common practical challenges for homes switching from a combi boiler. Typical locations include airing cupboards, utility rooms, and garages. Your installer will advise on the best location during the survey.

Should I get the preparation work done before or after getting heat pump quotes?

Get quotes first. A good installer will tell you what preparation work is needed as part of their survey. Doing insulation work before the survey is generally wise (it is beneficial regardless), but let the installer's recommendations guide specific choices like radiator upgrades.

Getting Started

Preparing your home for a heat pump is not about achieving perfection — it is about making sensible improvements that help the heat pump work efficiently and keep your running costs down. Start with insulation, get your EPC, clear a space outside, and then speak to MCS-certified installers who can guide you through the rest.

The effort you put into preparation pays back every year in lower bills and a more comfortable home.