Why Is My Heat Pump Using So Much Electricity?

Introduction

One of the most common concerns after a heat pump installation is electricity usage.

Many homeowners expect lower running costs than gas, so a higher-than-expected electricity bill can cause concern.

In some cases, higher usage is normal — especially during cold weather.

In other cases, it can indicate setup or commissioning issues.

Here’s what to check.

1. Flow Temperature Is Set Too High

Heat pumps are most efficient at lower flow temperatures.

If your system is running at 55–65°C constantly, efficiency drops significantly.

Typical efficient ranges:

• Underfloor heating: 30–40°C

• Radiator systems: 35–50°C (depending on design)

Higher flow temperatures increase electricity consumption and reduce COP.

2. Backup Heater (Immersion) Is Operating

Many systems have a built-in electric backup heater.

If this is running frequently, electricity usage will increase sharply.

This may happen if:

• The system is undersized 

• The flow temperature is set too high

• The system wasn’t commissioned correctly

• Legionella cycles are too frequent 

Checking whether the immersion is active is an important first step.

3. Weather Compensation Not Set Correctly

Modern heat pumps adjust output based on outdoor temperature.

If weather compensation is disabled or poorly set:

• The system may run hotter than needed 

• Efficiency drops

• Electricity use increases 

Correct curve setup can significantly reduce running costs.

4. Radiators Undersized

If radiators are too small for low-temperature operation:

• The flow temperature is increased to compensate 

• Electricity usage rises

• Efficiency drops

A heat pump relies on adequate emitter size to operate efficiently.

5. It Might Just Be Winter

During sustained cold weather, heat pumps run longer.

This doesn’t mean they’re inefficient — just that demand is higher.

It’s important to assess:

• Comfort levels 

• Flow temperatures

• Run times

• Backup heater usage

Rather than focusing on daily consumption alone.

Final Thoughts

Higher electricity usage doesn’t automatically mean something is wrong — but it does mean the system should be reviewed properly.

Common causes include flow temperature settings, emitter sizing, weather compensation configuration, or extended run times during colder weather.

If your system also runs most of the day, you may want to read:
Why Is My Heat Pump Running Constantly?

Flow temperature has a direct impact on electricity consumption.
See: What Flow Temperature Should My Heat Pump Run At? 

A correctly designed and commissioned heat pump should provide stable comfort at the lowest possible flow temperature.

If you're unsure whether your system is operating efficiently, you can book a structured heat pump review here.