Why Your Heat Pump Is Running Constantly (And Costing You a Fortune)

Introduction

One of the most common issues I get called out to across the Northeast is heat pumps running constantly with high energy bills and poor performance.

Recently, I attended a property where the system hadn’t switched off for weeks—yet the house still wasn’t heating properly.

The Symptoms

The customer reported:

• Constantly running heat pump

  
  
  
  

• High electricity bills

  
  
  
  

• Poor heating performance

  
  
  
  

• Hot water always being prioritised

  
  
  
  

• No obvious fault codes

  
  
  
  

The Root Cause

The issue wasn’t the heat pump itself—it was the control setup.

The domestic hot water (DHW) timer had been set to constant, meaning the system was permanently prioritising hot water production.

On top of that, the cylinder had a severely undersized coil (around 0.7m²), which is far too small for a heat pump system.

Technical Breakdown

Heat pumps rely on:

• Low flow temperatures

  
  
  
  

• Small delta T between flow and return

  
  
  
  

This means they require much larger coil surface areas compared to traditional boilers.

In this case:

• Required coil size ≈ 3m²+

  
  
  
  

• Installed coil size ≈ 0.7m²

  
  
  
  

👉 That’s less than 25% of what’s needed.

Result:

• Heat transfer is poor

  
  
  
  

• DHW never satisfies

  
  
  
  

• System runs continuously

  
  
  
  

The Fix

• Adjusted DHW timer settings

  
  
  
  

• Advised on correct cylinder specification

  
  
  
  

• Reviewed system controls and prioritisation

  
  
  
  

The Result

• Heat pump began cycling correctly

  
  
  
  

• Reduced runtime

  
  
  
  

• Improved heating performance

  
  
  
  

• Lower energy consumption

  
  

Could This Be Happening to You?

You might have the same issue if:

• Your heat pump never switches off

  
  
  
  

• Your bills are increasing

  
  
  
  

• Hot water takes forever to heat

  
  
  
  

• Your home never reaches temperature

  
  
  
  

Need Help?

I specialise in diagnosing and fixing underperforming renewable systems.

If your heat pump isn’t working as it should, I offer full system diagnostics and repair services across the Northeast including Durham, Teesside, North Yorkshire and surrounding areas.