Why Your Heat Pump is Expensive to Run

And why it’s almost never the heat pump itself

There’s a moment most heat pump owners have.

It usually comes a few months after installation, often when the first proper winter bill lands. You look at it and think:

“That can’t be right.”

Because somewhere along the line, you were told this system would be efficient. Cheap to run. A step forward from traditional heating.

And now it doesn’t feel like that at all.

Here’s the reality.

In the vast majority of cases, the heat pump itself isn’t the problem.

It’s everything around it.

The uncomfortable truth about heat pumps in the UK

Heat pumps are incredibly efficient pieces of equipment. That’s not marketing—it’s physics.

But they are also far less forgiving than gas boilers.

A boiler will happily mask poor design, poor setup, and poor controls. It can brute-force heat into a property and still feel like it’s working fine.

A heat pump can’t do that.

It relies on:

• Correct system design

• Accurate commissioning

• Proper control strategy

• Ongoing maintenance

If any of those are off—even slightly—the system will still run… but it will run badly.

That’s where high costs come from.

Systems that were never properly commissioned

This is one of the biggest issues we see, and it often goes unnoticed.

When a system is installed, commissioning is supposed to fine-tune everything:

• Flow rates

• Pump speeds

• Heating curves

• Control logic

In reality, this step is often rushed or reduced to “it turns on and heats the house.”

So what you’re left with is a system that technically works, but is nowhere near optimised.

It might:

• Run hotter than it needs to

• Cycle on and off unnecessarily

• Constantly chase temperature instead of maintaining it

And all of that quietly increases your running costs.

When the system was never right to begin with

Sometimes the issue starts even earlier.

If a heat pump is undersized, or installed onto a system that wasn’t properly adapted—such as radiators that are too small—it will struggle from day one.

To compensate, it has no choice but to:

• Increase flow temperatures

• Run for longer periods

• Work harder than it should

This is where the expectation gap appears.

You were sold efficiency, but the system is being forced to operate inefficiently just to keep up.

The silent killer: flow temperature

If there’s one setting that has the biggest impact on running costs, it’s flow temperature.

Heat pumps are designed to run at lower temperatures, steadily, over longer periods.

But many systems are left running far too high.

Why?

Because higher temperatures make the system feel more responsive. Rooms heat up quicker. Complaints are reduced in the short term.

But efficiency drops sharply.

So while it feels like it’s working better, it’s actually costing you more every hour it runs.

Weather compensation – used properly, or not at all

Weather compensation is often talked about as a solution, but rarely understood.

When it’s set up correctly, it allows the system to gently adjust output based on outdoor temperature, keeping things stable and efficient.

But what we often see is:

• It’s turned off completely

• The curve is set too high

• Or it’s constantly overridden

Then it gets written off as “not working.”

The problem is, weather compensation isn’t instant. It needs time to settle. It needs a stable system around it.

Without that, it never gets the chance to do what it’s designed to do.

Heat loss you can’t see

Even with a well-set system, heat loss plays a huge role.

If the property is losing heat faster than it should, the heat pump has to keep replacing it.

That might be:

• Loft insulation that isn’t up to standard

• Draughts around windows and doors

• Or something as simple as poorly insulated pipework

We regularly see outdoor pipework losing heat before it even reaches the house.

It’s small losses, but they add up—hour after hour, day after day.

The servicing myth

One of the biggest misconceptions in the industry is that heat pumps are “low maintenance.”

What that often translates to is: no maintenance at all.

Over time:

• Strainers clog

• Flow rates drop

• Air builds up in the system

• Performance slowly declines

You don’t always notice it straight away. It just becomes the new normal.

But your running costs creep up.

And importantly, many manufacturers require regular servicing to keep the warranty valid. That part is often overlooked completely.

Using it like a boiler

This is probably the most understandable mistake—and one of the most damaging.

People are used to boilers. Quick heat, on-demand, instant response.

So they:

• Turn the system on and off

• Increase temperatures to “boost” heat

• Expect quick changes

But a heat pump isn’t designed to behave like that.

It’s designed to run in the background, steadily maintaining temperature.

When you force it into stop-start behaviour, it becomes less efficient and more expensive to run.

Why advice online doesn’t always fix it

There’s no shortage of advice out there.

Lower this. Adjust that. Change a setting.

And sometimes it helps.

But if the underlying system isn’t right—if it was poorly commissioned, poorly designed, or has underlying issues—those tweaks only go so far.

That’s why some people follow everything they’re told and still end up frustrated.

What actually makes the difference

When a heat pump system is set up properly, everything changes.

It doesn’t fight to heat the house.It doesn’t constantly switch on and off.It doesn’t need high temperatures to keep up.

It just runs.

Quietly, steadily, efficiently.

And that’s when the running costs start to make sense.

When a few tweaks aren’t enough

There’s a point where adjusting a couple of settings isn’t going to fix the problem.

If a system has been:

• Poorly commissioned

• Incorrectly set up

• Running inefficiently for a long time

…it usually needs a proper, structured review.

That means looking at the whole system properly:

• Flow temperatures and heating curves

• System flow rates

• Controls and how they’re being used

• Hot water setup

• Overall performance against what the system should be doing

Because until you see the full picture, you’re just guessing.

This is exactly what a performance review is for

A system performance review isn’t about selling you new equipment.

It’s about getting the most out of what you already have.

In many cases, improvements come from:

• Correcting setup issues

• Optimising controls

• Fine-tuning how the system runs

Small changes—but with a big impact on efficiency and running costs.

Final thought

If your heat pump is expensive to run, it doesn’t mean the technology is wrong.

It usually means something in the setup isn’t right.

And the good news is, most of the time, that can be fixed.