Mywarm

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It works a bit like a fridge in reverse.

Heat pumps move energy so we can heat our homes and provide hot water.

A heat pump transfers heat from air, ground, or water to heat homes efficiently, using electricity to move energy rather than generate heat, cutting emissions and running costs significantly overall.

It can be confussing!.

A heat pump takes heat from one place (outside air, the ground, or water) and moves it into your home. Even cold air contains heat. The system gathers that heat, boosts it, and releases it indoors.

It works a bit like a fridge in reverse:

  • A fridge pulls heat out of food and dumps it into your kitchen
  • A heat pump pulls heat from outside and dumps that heat it into a refrigiration cycle.
  • Through the magic of refrigirants the low temperature heat if squeezed (molocules) to increase the heat that can be used for our radiators or underfloor heating.

How it actually warms your house.

  1. Heat is collected from outside (air, ground, or water).
  2. That heat is compressed to raise its temperature.
  3. The warmed heat is delivered to radiators, underfloor heating, blower units, or hot water.
  4. The cycle repeats, quietly and continuously.

You may ask how can heat energy be in cold water, the ground or cold air?

Well thats the confussing part that can be hard to understand. Heat is always around us, even when it feels cold.
The air, the ground and water all contain natural heat energy because they’ve absorbed warmth from the sun and the earth over time. Even on a chilly day, there is still energy in the air, it’s just at a low temperature.
Modern heating systems like heat pumps don’t create heat from scratch; they simply collect this existing, low-level warmth and concentrate it to a higher temperature that can be used to heat your home. So instead of making heat, we’re just capturing and upgrading the heat that’s already there.

Because it’s moving heat rather than creating it, it uses much less energy than traditional heating when designed and specified properly.

Some heat pumps can be 400% efficient.

When people say a heat pump is “400% efficient”, it doesn’t mean it’s magically creating energy. It means for every 1 unit of electricity you put in, you get about 4 units of heat out. Abbreviations like “SCOP (seasonal coefficient of performance” and “COP (coefficient of performance)” are used and this is where the % comes from.

  • COP = today’s efficiency
  • SCOP = the yearly average efficiency

SCOP is the number that really matters for running costs.

The Different Types of Heat Pumps.

If you’re considering replacing your current heating and hot water system with a renewable alternative, it’s essential to be aware that this can be a significant investment. In many cases, it involves a partial or complete system upgrade, as heat emitters and pipework often (though not always) need to be updated to achieve optimal flow rates.

To determine if a heat pump is suitable for your property, you can consult the UK government’s suitability guide. The MCS best practice is here. or use our own quick suitability checker.

Heat Pump Suitability Checker

The primary types of heat pumps used in the UK include:

  • ASHP: Air Source Heat Pumps.
  • WSHP: Water Source Heat Pumps.
  • GSHP: Ground Source Heat Pumps.
  • AA: Air to Air Heat Pumps.

New additions are the Exhaust Heat Pump system. coming soon.

A hybrid system is another option to consider, where a fossil fuel-powered boiler (like gas) works alongside a heat pump. This setup can help meet increased heating demands during the colder winter months while still reducing overall reliance on non-renewable energy sources

Although all heat pumps work on the same principle, they collect heat in different ways:

  • Air Source Heat Pumps (ASHP)
    These draw heat from the outside air using a unit that looks similar to an air conditioner — because it almost is one, just working the other way around.
  • Water Source Heat Pumps (WSHP)
    These collect heat through coils or mats placed under the surface of a pond, lake, or river.
  • Ground Source Heat Pumps (GSHP)
    These use long loops of pipe buried in the ground — either horizontally about 2 metres deep or vertically down boreholes reaching around 100 metres.
ASHP
Coils for WSHP
Manifold Chamber GSHP

Once the heat is gathered, it’s transferred into your home through radiators, underfloor heating or blower units, depending on your home’s design and comfort preference.

This technology is new to many of us, and it needs to be used a little differently.

During the heating season, it’s best to control your home’s temperature rather than demand it. In other words, let the system maintain a steady temperature instead of turning it off and on all the time. It’s more efficient (and cheaper) to let the heat pump gently adjust the temperature up or down.

Most modern systems use outdoor temperature sensors to help with this. These sensors measure the air temperature outside and tell the heat pump how much heat your home is likely to need. On mild days, the system runs at a lower level; when it’s colder, it automatically increases output. This helps your heat pump work in tune with the weather — keeping your home comfortable while using less energy overall.

Typical Curve
UFI manifold
Outdoor Sensor

Things to consider ASHP.

Position. 

Away from sleeping and noise-sensitive areas. (newer ASHPs are very quiet).
Making sure the area around the heat pump is to manufacturers guidance to allow optimum airflow and service needs. Do not cover as this will restrict the free air around the unit that allows it to efficiently work.

Condensation removal. 

Water will come from the unit and can pool. It’s not the same as gas boiler condensate, which can be acidic, so just basic removal to soak away or drain, depending on the manufacturer’s instructions.

Radiator sizes and pipework. 

Heat pumps work at lower temperatures, so a bigger surface area, ideally underfloor heating, is beneficial. (see delta T in technical area)

Insulation of property. 

The better the wall and loft (or room in roof) insulation, the less heat loss. (see insulation)

Uninsulated pipework. 

Storaed hot water supplies and central heating pipework at the plant should all be insulated. All external pipework should be insulated with a class 0 UV protected insulation.

Maintenance requirements. 

Refer to manufacturers literature regarding serviceing. As a rule of thumb the unit should be checked yearly and basic cleaning of internal fins and casing should be performed. A clear pathway and area surrounding unit should always be available.

Running costs. What is the average yearly cost to run the heat pump! This can be really important, and research and information from your installer is a must. 

Solar matching. 

As heat pumps operate differently through the seasons, the same goes for solar. If you are having solar PV installed and thinking the panels will run the heat pump, then think again. You could try to match the solar generation to the heat pumps output, which could help with running costs.

Understanding heat pump efficiency: SCOP and COP.

When looking at heat pumps, you’ll often see the terms COP and SCOP. These are simply ways of measuring how efficiently your system turns electricity into heat.

COP — Coefficient of Performance.

Measures efficiency at one moment in time — usually in perfect test conditions.

For example, a COP of 4 means that for every 1 unit of electricity the heat pump uses, it provides 4 units of heat.
However, real life isn’t always perfect — temperatures change, systems switch on and off, and conditions vary throughout the year. That’s where SCOP comes in.

SCOP — Seasonal Coefficient of Performance.

Gives a more realistic picture of your heat pump’s efficiency over an entire heating season.

It takes into account:

  • Changing outdoor temperatures as the weather warms and cools.
  • Energy used during standby and defrost cycles.
  • How efficiently the system runs at different power levels.

In short, SCOP tells you how efficient your heat pump is across the whole year, not just in ideal lab conditions.

How is SCOP Is calculated?

SCOP compares how much heat energy your system produces with how much electricity it uses:

SCOP = Total Heat Output ÷ Total Electricity Used

Example.

If your heat pump has a SCOP of 4, that means for every 1 kWh of electricity it uses, it provides 4 kWh of heat.
That’s why people often say a heat pump can be “400% efficient” — it’s not creating energy, just moving it very efficiently.

Privately installed or funded?

For any renewable heating project, whether funded privately or through a UK funded scheme, the current best practices, manufacturer’s instructions and relevant building regulations should be strictly adhered to.
If installed on a UK funded scheme then a quality assurance program that certifies small-scale renewable energy systems and installers need to be followed, currently this is called MCS if insulation is being carried out at the same time and as part of the funding then it must meet the current PAS. 

Have a look at the funding area of the site for more information especially the changes to the ECO scheme.

Installation Guide.

The manufacturer’s instructions will highlight any regulations that are required. Currently, all electrical regulations need to be followed and documented, as is the MCS checklists if installed on government scheme. Requirements are that properties are well insulated prior to the installation (fabric first approach) and full heat loss calculations are carried out to provide information to install the system to best practice.

If hot water is being heated in storage tanks by the heat pump then steps need to be taken to protect from bacterial growth. Stored hot water systems connected to heat pumps have cycles to heat the water at given times and a given temperature to stop the growth of Legionella bacteria.

Electrical certificates.

The two types of electrical certificates you will come across as a customer who is having any electrical work as part of installing EEM’s (energy efficient measures)

  • Electrical Installation.
  • Minor Works Certificate.

Electrical Installation Certificate.

An electrical installation certificate is the type of certificate a customer receives after an electrician has installed one or more new circuits. Other examples include a complete rewire, a replacement consumer unit or an additional consumer unit. Generally, any time electrical work is done at the consumer unit, a new installation certificate will be issued.

Minor Works Certificate.

A minor works certificate is issued after an electrician has made an alteration to an existing circuit. Minor works certificates are often used to certify work such as adding additional sockets to an existing circuit or increasing the number of light fittings in a room. It can also be where a fused spur has been installed for an appliance or boiler connection.

Major Heat Pump Manufacturers.

UK

European manufacturers

Asian manufacturers

Emerging manufacturers