We have lived with a 5 kW Vaillant aroTHERM heat pump since October 2022. Over that time, it has given me plenty of hands on experience of what day to day heat pump ownership actually looks like, and how it works alongside solar PV, home batteries, and time of use electricity tariffs.
That has meant a lot of data, plenty of lessons learned, and a growing list of practical do’s and don’ts. Just as importantly, it has given me the time to understand what really makes a heat pump perform well in the real world.
As a result, I have written a large number of articles, guides, tools, and calculators, all based on real measurements rather than theory.
Everything linked from this page comes from that experience.
Heat Pump Performance for Normal People
I wrote this article (Heat Pump Performance for Normal People) to hopefully explain not only how heat pumps perform, but also what makes them different to a gas boiler.
As well as other things you can expect if you’re considering making the transition yourself. Like COP / SCOP and how weather compensation works.
Heat Pump Performance for Normal People
Heat Pump Myths Busted
In Heat Pump Myths Busted I tackle many of the criticisms of heat pumps you hear about online.
Having lived with a heat pump for over 3 years I think I’m in a good position to counter many of these arguments with my own experience.
Heat Pump Myths Busted: Real Insights from a UK Family Home
Best Tariff for Heat Pump
Choosing the best electricity tariff for heat pump can be crucial for running costs.
In this Best Heat Pump Tariff article we look at the options available from Octopus Energy and the different strategies you can employ depending on the renewable kit that you already may have (solar, batteries, EV etc).
Best Heat Pump Tariffs UK 2026 | Save with Renewable Strategies
Best Heat Pump Hot Water Settings (The Golden Rules)
After years of trials and me messing about I came up with what I consider the be the golden rules for hot water generation with a heat pump.
This Best Heat Pump Hot Water Settings article provides evidence based advice and settings to get the most efficient and cheapest hot water you can from your heat pump, regardless of manufacturer.
Best Heat Pump Hot Water Settings (The Golden Rules)
How Much Electricity Does a Heat Pump Use?
This “how much electricity does a heat pump use” article is inspired by the questions raised on a recent Gary Does Solar video about battery sizing.
His video talked about what size home battery to buy and how to think about your historical electricity usage to help guide your decision.
So in this post I explain and help you calculate how much electricity a heat pump might use each day. Once you see those numbers it is much easier to understand what role, if any, a home battery can play.
How Much Electricity Does a Heat Pump Use?
Free Heat Loss Survey Tool (what size heat pump from your gas data)
Getting the right size heat pump installed is crucial to ensure good performance and low running costs.
With this Free Heat Loss Survey Tool you can use gas usage data from very cold days along with the outside and inside temperature to get a ball park estimate for the heat loss of your house.
Note: this does not replace a full room by room and total heat loss survey from a qualified and experienced installer, but it can help give you an idea about heat loss numbers.
Free Heat Loss Survey Tool – What Size Heat Pump?
Why does my heat pump defrost in winter?
If you own an air source heat pump, you’ve probably seen it pause on a cold day, blow out a burst of steam, then get back to heating as if nothing happened. That’s the defrost cycle. It can look dramatic, but it’s a normal way the system protects itself in cold humid weather.
Homeowners often search for things like why does my heat pump defrost, why is my heat pump defrosting so often in winter, or heat pump icing in cold humid weather.
This Heat Pump Defrost guide explains what is happening, why it happens more in the UK, and what to look for if it seems excessive.
Heat pump defrost: why it happens in UK winters
Heat pump cycling and minimum modulation
If you’ve noticed your heat pump clicking on and off a lot in spring or autumn, don’t panic. That’s cycling and in most cases it’s completely normal.
Because your house doesn’t need much heat when it’s mild outside. At some point the demand drops below your heat pump’s minimum heat output (its “can’t go any lower” point). When that happens, the unit has to cycle, turning off for a while, then back on again, to avoid overheating the house.
If it didn’t do this, the heat pump would just run constantly and you’d end up far too warm indoors.
We have a dedicated heat pump cycling calculator and in this cycling and minimum modulation article we go into why it happens and whether the amount you’re seeing is normal.
Heat Pump Cycling and Minimum Modulation
Living with our 5kW Vaillant Arotherm Heat Pump
I’ve written a lot about my own heat pump over the years and how it performs in our 1930 semi detached house in Sheffield.
If you are interested in what living with a heat pump is like, regardless of manufacturer, these are a good starting point.
I have roundups across various winters with the heat pump as well as raw month by month performance figures in the history article.
First Winter with my Air Source Heat Pump
Second Winter with our Vaillant ASHP
Third Winter with our Vaillant Heat Pump
My Heat Pump Performance History
Heat Pump Performance History – 3 Years UK Home Data
Hot Water and Cylinder Articles
This section lists all the articles related to hot water, heat pumps and my Mixergy cylinder.
Arotherm Arotherm Hot Water Modes
The Problem with Eco Hot Water Mode
Mixergy Usable Hot Water Capacity Test
The Heat Pump Hot Water Golden Rules
A Review of 700 Heat Pump Hot Water Runs in 2024
Support the Site
Join Octopus Energy – Get £50 Free Credit
Homeowners who join Octopus Energy using my referral link get £50 free credit after signing up. Business users get £100 free credit, and if you’re looking at solar or a heat pump, there’s also a £100 gift card through Octopus Tech.
Buy Me a Coffee
If you’d rather just send a small one-off thank you, you can buy me a coffee here. It’s a nice way to show support, and it all goes back into running the site.
Other Ways to Support
You can also see more ways to support the site here via the likes of Plusnet broadband, Smarty Mobile, Havenwise remote heat pump control, Hetzner Cloud hosting and more.
Follow Energy Stats UK on Social Media
Follow @energystatsuk on Twitter / X, Bluesky and Mastodon for daily energy tariff graphs and updates.
General Heat Pump and Heating Articles
Lots of more general heating and heat pump related articles here:
Smaller Heat Pumps will never reach Top of the SCOPS
Heat Pump Cycling and Minimum Modulation
Heat Pump Performance for Normal People
How Much Electricity Does a Heat Pump Use
Real World UK Winter Heat Pump COP
Tools and Calculators
In this section you will find direct links to a number of tools and calculators that I have created:
Free Heat Loss Survey Tool (what size heat pump from gas data)
Vaillant Arotherm Heat Pump Guide
Having owned our Vaillant Arotherm 5kw Heat Pump since 2022 means I’ve been able to collect a lot of knowledge about the unit and how it performs.
The blog section of the website is full of various Arotherm related material, but the information is spread across many articles.
So this has been all pulled together into one single article called: Vaillant Arotherm Heat Pump Guide.
From within there you can jump to any of the topics that interest you.
If you own a Vaillant Arotherm heat pump or are considering one, this single article will help you get the most out of setting up, monitoring, and fine-tuning.
The guide contains a whole host of useful Vaillant Arotherm articles, which I will list here too:
Vaillant Arotherm Basic Heating Settings
Vaillant Arotherm Basic Hot Water Settings
Vaillant Arotherm Performance Tables and Interactive Widget
How to View Vaillant aroTHERM Live Data
Energy Tariffs
As well as heat pump articles, Energy Stats UK is a hub for energy tariff data. Be sure to head over to the Energy Tariff landing page to find out about smart tariffs like Octopus Agile, Octopus Cosy, Octopus Tracker and bunch of other interesting stuff like Wholesale Energy Costs.
Recent Blog Articles
Referral information and free credit offer
If you find Energy Stats UK useful, there are a couple of easy ways to support the site and help cover hosting and server costs.
Thinking about switching energy suppliers?
Homeowners who join Octopus Energy using my referral link get £50 free credit after signing up. Business users get £100 free credit, and if you’re looking at solar or a heat pump, there’s also a £100 gift card through Octopus Tech.
Finally, a £25 gift card can be claimed when having an EV charger installed through Octopus.
Or, if you just want to say thanks, you can buy me a coffee.
You can also see more ways to support the site here via the likes of Plusnet broadband, Smarty Mobile, Havenwise remote heat pump control, Hetzner Cloud hosting and more.
Follow @energystatsuk on Twitter / X, Bluesky and Mastodon for daily tariff graphs and updates.
Note: The current and past performance of energy pricing is not necessarily a guide to the future.
