Home Heat Pump Guide

Heat Pump DNO Notification: Do You Need One?

When you install a heat pump, there is one administrative step that catches many homeowners off guard: notifying your Distribution Network Operator (DNO). Depending on the size of your heat pump and your existing electrical supply, you may need to let your local electricity network know before the installation goes ahead.

The good news is that DNO notification is straightforward, usually free, and your MCS-certified installer will typically handle it for you. This guide explains exactly when you need one, how the process works, and what happens if the DNO flags an issue with your supply.

What Is a DNO and Why Does It Matter?

A Distribution Network Operator is the company that owns and maintains the electricity cables, substations, and infrastructure that deliver power to your home. There are six regional DNOs covering Great Britain:

  • UK Power Networks (UKPN) — London, South East, and East of England
  • Western Power Distribution (NGED) — Midlands, South West, and Wales
  • Northern Powergrid — North East and Yorkshire
  • Electricity North West — North West England
  • Scottish Power Energy Networks — Central and Southern Scotland, North Wales, and Merseyside
  • Scottish and Southern Electricity Networks (SSEN) — Northern Scotland and central Southern England

Your DNO is different from your energy supplier. The supplier sends your bill; the DNO manages the physical cables and infrastructure. When you add a significant new electrical load like a heat pump, the DNO needs to know so they can check the local network can handle it.

When Do You Need a DNO Notification?

The key threshold is 16 amps per phase. Under the Engineering Recommendation G98/G99 framework and the Electricity Safety, Quality and Continuity Regulations (ESQCR), you need to notify your DNO if:

  • Your heat pump draws more than 16A on a single-phase supply (roughly 3.68 kW)
  • You are connecting any new large electrical load that takes your total demand above the capacity of your existing supply
  • Your installer identifies that your existing electrical supply (typically a 60A or 80A fuse) may not have enough headroom

In practice, most air source heat pumps draw between 2 kW and 6 kW of electrical power, which translates to roughly 8A to 26A on a single-phase supply. Smaller heat pumps for well-insulated homes may slip under the 16A threshold, but the majority of domestic installations will require at least a notification.

Single-Phase vs Three-Phase Supplies

Most UK homes have a single-phase electricity supply with a 60A or 100A main fuse. Larger properties sometimes have a three-phase supply. The notification rules differ:

  • Single-phase: Notification required if the heat pump draws over 16A, or if the total household demand (existing appliances plus heat pump) risks exceeding your main fuse rating
  • Three-phase: Generally more headroom available, but notification is still required for loads above 16A per phase

If you also have or plan to install an electric vehicle charger or solar panels, the combined load becomes especially important. Your installer should assess the total electrical demand, not just the heat pump in isolation.

The DNO Notification Process Step by Step

Step 1: Your Installer Assesses Your Supply

During the initial survey and design stage, your MCS installer will check your existing electrical supply. They will note your main fuse rating, the condition of your consumer unit, and the total anticipated electrical load once the heat pump is added.

Step 2: The Installer Submits the Notification

If a notification is required, your installer submits it to the relevant DNO. Most DNOs now have online portals that make this straightforward. The notification typically includes:

  • Your address and MPAN (Meter Point Administration Number)
  • The make, model, and electrical rating of the heat pump
  • The expected maximum demand in amps or kilowatts
  • Details of any other significant electrical loads (EV charger, electric shower, etc.)

Step 3: The DNO Reviews

The DNO checks whether the local transformer and cables serving your property can handle the additional load. In most cases, they approve the connection within a few working days. They may come back with one of three outcomes:

  • Approved as notified — no issues, proceed with installation
  • Approved with conditions — for example, they may upgrade your main fuse from 60A to 80A or 100A at no cost
  • Further assessment needed — rarely, the local network may need reinforcement before a new large load can be connected, which could delay installation

Step 4: Installation Proceeds

Once the DNO gives the green light, your heat pump installation can go ahead as planned. The DNO notification is just one part of the wider installation process, but it needs to happen early to avoid delays.

How Long Does DNO Notification Take?

Timelines vary by DNO, but as a general guide:

  • Simple notification (no issues): 5–10 working days
  • Fuse upgrade required: 2–6 weeks, depending on the DNO's workload
  • Network reinforcement needed: 3–6 months in exceptional cases

The vast majority of domestic heat pump installations fall into the first category. Your installer will factor the notification timeline into the project schedule, so in most cases it does not delay the actual installation date.

Does DNO Notification Cost Anything?

For a standard domestic heat pump installation, DNO notification is free. The DNO is legally required to process notifications and make reasonable accommodations to their network at no charge to the consumer. If your main fuse needs upgrading (for example, from 60A to 100A), the DNO will do this free of charge in most circumstances.

The only scenario where costs might arise is if the local network requires significant reinforcement — for example, if the transformer serving your street is already at capacity. This is uncommon in residential settings, and if it does apply, the DNO will explain the costs and timescales upfront.

What If My Main Fuse Needs Upgrading?

Many older UK homes still have a 60A main fuse. Adding a heat pump that draws 10–15A on top of your existing load (electric shower, oven, lighting, appliances) can push the total close to or above 60A. In this case, the DNO will upgrade your fuse — typically to 80A or 100A.

Key points about fuse upgrades:

  • The upgrade is carried out by the DNO, not your heat pump installer
  • It is free in the vast majority of cases
  • It usually involves a brief power cut of 30–60 minutes
  • The DNO may also replace your meter tails (the cables between the meter and consumer unit) if they are undersized

Your installer may also recommend upgrading your consumer unit (fuse box) to accommodate the new circuit for the heat pump. This is a separate cost — typically £300 to £600 — and is carried out by a qualified electrician as part of the overall installation.

Does My Installer Handle All of This?

Yes, in almost all cases. Any reputable MCS-certified heat pump installer will manage the DNO notification as part of their standard service. It is one of the reasons working with an experienced, accredited installer matters — they know the process inside out and will submit the notification at the right time to avoid holding up the installation.

If you are getting quotes, it is worth asking each installer:

  • Have you assessed whether a DNO notification is needed?
  • Is the DNO notification included in your service?
  • Have you checked the main fuse rating and supply capacity?

If an installer seems unfamiliar with the DNO process, consider it a red flag.

Common Scenarios

Scenario 1: Modern Home, 100A Supply

A 2010-built detached house with a 100A fuse and no electric vehicle charger. The heat pump draws 12A. Total household peak demand is well within 100A. A notification is still submitted, but the DNO approves without any changes needed.

Scenario 2: Older Home, 60A Supply

A 1960s semi with a 60A main fuse, electric shower (40A), and basic appliances. The heat pump draws 14A. Peak demand could exceed 60A. The DNO approves but upgrades the fuse to 100A free of charge before installation.

Scenario 3: Rural Property, Long Cable Run

A farmhouse at the end of a long overhead line. The existing supply struggles with voltage drops during high-demand periods. The DNO identifies that the cable needs reinforcing. This delays installation by several months, but the upgrade benefits the property long-term.

DNO Notification and the Boiler Upgrade Scheme

If you are claiming the Boiler Upgrade Scheme (BUS) grant, the DNO notification is part of the standard installation process that your MCS installer must follow. It does not affect your eligibility for the £7,500 grant, but the installation must be completed by an MCS-certified installer who follows all required procedures — including DNO notification where applicable.

Frequently Asked Questions

Do I need DNO notification for every heat pump installation?

Not necessarily. Very small heat pumps that draw less than 16A on a single-phase supply may not require formal notification. However, your installer should always assess your electrical supply capacity regardless, and most domestic heat pumps do exceed the 16A threshold.

Can I submit the DNO notification myself?

Technically yes, but it is almost always better to let your MCS installer handle it. They have the technical details to hand and know exactly what information the DNO requires. Some DNO portals are also designed primarily for installer access.

Will DNO notification delay my heat pump installation?

In most cases, no. A straightforward notification is processed within 5–10 working days. Your installer will submit it early in the project timeline. Delays only occur if the DNO identifies a need for supply upgrades or network reinforcement.

Is there a charge for DNO notification?

No. DNO notification for a domestic heat pump is free. Fuse upgrades carried out by the DNO are also typically free. Costs only arise in rare cases where significant network reinforcement is required.

What happens if I install a heat pump without notifying the DNO?

Installing without notification when one is required is a breach of regulations. It could void your insurance, create safety issues if your supply is overloaded, and cause problems if you later need to claim the BUS grant. There is no good reason to skip this step.

Does my energy supplier need to know about my heat pump?

Your energy supplier does not need formal notification, but it is worth telling them. They may be able to offer you a heat pump-specific tariff (such as a time-of-use tariff) that could reduce your running costs. Some suppliers also offer the Demand Flexibility Service payments that reward you for shifting electricity use to off-peak times.

Key Takeaways

DNO notification is a routine part of preparing your home for a heat pump. It exists to ensure the local electricity network can handle the additional load safely. For most homeowners, it is handled entirely by the installer, costs nothing, and causes no delays. The only thing you need to do is choose a competent, MCS-certified installer who includes this step as standard.

If you are concerned about your electrical supply capacity — especially if you have an older home with a 60A fuse, or you are also planning an EV charger — raise this with your installer during the initial survey. Getting the DNO notification submitted early is the simplest way to keep your installation on track.