Do I Need a Hot Water Tank with an Air Source Heat Pump?

If you’re considering switching to an air source heat pump, one of the most common questions is:

“Do I need a hot water cylinder as well?”
 In most cases — yes, you do. But don’t worry, we’re here to explain why, what type you’ll need, and what it means for your home.

Whether you live in a bungalow in Edinburgh or a detached house in the Lothians, this guide covers everything you need to know about heat pumps and hot water cylinders.

🔍 Why Air Source Heat Pumps Work Best with Hot Water Cylinders

Air source heat pumps (ASHPs) produce hot water differently than traditional gas boilers. They: 

• Work at lower flow temperatures (typically 35–55°C)
  
• Heat water gradually and efficiently to your desired temperature 
• Are most effective when paired with a well-insulated cylinder to store hot water
  

This stored water is then available for your taps, showers, and baths, just like with a traditional system.

🛠 So… Do You Have to Have One?

In most standard installations:
 ✅ Yes — a hot water tank is needed.

This is especially true if:

• You want plenty of hot water for multiple bathrooms
  
• You use standard radiators or underfloor heating
  
• You’re applying for funding through Home Energy Scotland
  

However, there are some exceptions…

🧯 Are There Any Alternatives?

If space is tight or your hot water usage is low, there are a couple of other options:

1. Heat Pump Without Hot Water (Space Heating Only)

You can install an air-to-air heat pump or use an air-to-water system purely for heating. But you’ll still need another system (like an electric shower or immersion heater or Sunamp) to handle hot water.

 ✅ Less space required
 ❌ Less efficient overall unless heated by solar etc

Latent Haet will guide you to the right system based on your available space, usage, and budget.

📏 Where Will the Cylinder Go?

If you don’t already have a hot water cylinder, we’ll help find the right location. Common options include:

• Airing cupboard (where old units might have been)
  
• Utility room
  
• Loft or basement (in some homes)
  
• Under the stairs if there is sufficient space
  

We’ll measure up during your home survey and suggest a solution that fits your space.

🌡 What Type of Cylinder Do I Need?

For heat pumps, you need a heat pump-compatible cylinder — not a standard boiler cylinder. These:

• Have a larger internal coil to maximise heat transfer
  
• Are well-insulated to retain warmth
  
• Come in sizes from 150L to 300L+, depending on household demand
  

For a typical family home, we’ll often recommend a 200–250L cylinder.

💷 Will It Add to the Cost?

Yes — a cylinder will form part of the total installation cost. But:

• It’s included in your quote from the start
  
• It’s eligible for support through the Home Energy Scotland Grant & Loan Scheme
  
• It’s a one-off investment in long-term comfort and efficiency
  

And remember — storing hot water means you’re heating it efficiently, not on-demand with costly electricity or gas.

📍 Why Latent Heat Edinburgh?

We’re local, trusted MCS-accredited installers with experience fitting heat pumps in:

  ✅ Family homes

  ✅ New-builds and retrofits

  ✅ Period homes

We’ll help you find the right hot water solution for your space — and make sure your home is ready for low-carbon heating.

🧼 So… Do You Need a Hot Water Tank?

Ready to Find Out More?

Let us take the guesswork out of your home heating upgrade.

📍 Based in Edinburgh, the Lothians, or Fife?

 🧮 Book a free home survey with Latent Heat Edinburgh and we’ll design a heat pump system that’s the perfect fit for you.