The best ways to run your heat pump

Keep your heating bills down

There are two main ways to keep heat pump costs low: lowering the cost of energy with a smart tariff or maximising the efficiency of your heat pump and improving the SCOP. The way these options work is slightly different. Here’s how to make both work for you.

Save with a smart tariff

Overall, we’ve found that customers save the most money on a smart tariff like Cosy Octopus or a similar smart tariff like Intelligent Octopus Go.

The choice of smart tariff depends on which technologies you own (such as solar panels or an EV), and your lifestyle. For now, we’ll focus on just your heat pump and tariff tailored for heat pump homes: Cosy Octopus.

Cosy Octopus offers three ‘dip’ periods of super cheap energy every day, and one more expensive period during the ‘peak’ time. So we recommend setting your schedule to give you more heat during the cheaper ‘dip’ periods whenever possible, and reducing the temperature during the ‘standard’ periods. Find recommendations for schedule temperatures here.

This will mean changing your setpoint (the desired target temperature of your home) to make use of these periods. Because your heating won’t be kept at a continuous temperature, you’ll use a bit more energy and decrease your overall efficiency during the heating periods. But you will likely have saved money by using cheaper rate electricity–which also corresponds with when the grid is greenest. So even though you’re using a bit more power, you’ll pay less for it overall while reducing your carbon impact.

To find out the best way to run your heat pump on Cosy Octopus, see our guide.

Maximising efficiency (getting the best SCOP)

If you’d prefer to stick with a standard fixed or flexible tariff, you may choose to reduce monthly bills by boosting the efficiency of your heat pump instead. This usually means running your heat pump at a consistent, lower temperature all day rather than scheduling the temperature to change depending on the dip and peak periods.

When it comes to cost, your temperature setpoint makes a big difference. A good comfort setting for a heat pump would be around 19° or 20°. If you set it to 22°, for example, then the heat pump will stay on longer until the room temperature meets the target. This is likely to cost a bit more, and may reduce your efficiency (SCOP). It’s also worth noting that if you have good insulation, heat will be retained for longer, but remember that warmer homes lose heat faster than cooler ones regardless of insulation. So if you make your home extra warm, your heat pump will not only have to work harder but will run longer and more frequently.

Most textbooks recommend running heat pumps continually at low temperatures (around 19°), apart from when you’re out or sleeping. If the temperature isn’t consistent, the heat pump is forced to work hard to bring the temperature of the room up. When it hits the setpoint target, it doesn’t need to work as hard to maintain that temperature, keeping it working efficiently for longer (a lot like how a car gets better mileage cruising on the motorway than in stop-and-go traffic). This method should have your heat pump meeting or exceeding a SCOP of 3.3, which Octopus has designed your heat pump to achieve.

What is the SCOP and why is it important?

Coefficient of Performance or ‘COP’ is a figure that’s often used to measure the efficiency of your heat pump. COP is a simple measure of the power your heat pump consumes (energy in) versus the heat it produces (energy out) COP can therefore have an impact on the cost of running your heat pump. Low COP indicates lower efficiency, and a high COP indicates higher efficiency.

COP is the efficiency measured over a short period of time, whereas the Seasonal Coefficient of Performance, or 'SCOP', is measured over a full 12 months.

You can think of it, again, like driving your car. If you drive 30 miles in one hour, your average speed is 30 miles per hour. That’s like SCOP–it’s an average speed over time. But over those 30 miles of driving, you might have seen 70 mph on your speedometer at one moment, and zero mph a few minutes later while stopped at a junction. That’s like COP–it’s a discrete, short-term glimpse of performance that doesn’t give you the whole picture.

COP is influenced by various factors, but it’s mainly affected by what’s happening in your home. Making hot water is less efficient because your heat pump works extra hard to boost a lot of water to 50º or more. Space heating is much more efficient.

Another factor can be the temperature outside. For example, on the coldest day of winter, if you are extracting heat from the air to warm up the water, then efficiency will be lower and so will the COP. However if you are doing the same on a warm summer day, the efficiency (and COP) will be high. So don’t be alarmed if your COP is lower during colder months - this is normal.

SCOP VS COP

Octopus Energy designs heat pump installations to achieve an average SCOP of 3.3 over a 12-month period, using a design flow temp of 50° at the coldest times of the year.

This means that there are times throughout the year when your COP might be higher (e.g over 4 in the warmer months) or lower (e.g. it may dip down around 2.0 on the coldest days). But over 12 months, your heat pump should meet a SCOP of 3.3 at your design temperature–and many will be even higher.

Get more help with your heat pump