If you’re considering a heat pump or had one recently installed, this article is for you. Our six-year journey with a heat pump has been a rollercoaster of expensive mistakes, lessons learned and a mission to help others avoid our pitfalls. Heat pumps are incredible technology when installed and designed correctly. But when things go wrong, they can become a source of great frustration. Here’s what you need to know to ensure your heat pump journey is a success.

The Start of Our Heat Pump Journey

Six years ago, after an extensive vetting process, we appointed Global Energy Systems to install our air source heat pump. Global Energy Systems supplied the unit and subcontracted the physical installation to another MCS-accredited company, All Seasons Energy, while maintaining the full contract with us.

From the very beginning, it was evident something was amiss. The first three winters were plagued with issues: rooms that wouldn’t heat properly, issues with the controls and higher than expected running costs, temporarily obscured by the cushion of cheap electricity tariffs at the time.

Each time Global Energy Systems dispatched a team to address our concerns, we talked ourselves into believing things had improved – perhaps out of desperation to justify the £16,000 investment in the system. But as soon as the next cold spell hit, the same problems reared their ugly heads. In hindsight, it’s glaringly obvious: the installation wasn’t just flawed – it was fundamentally botched from the start.

A System That Was Never Designed to Work

One of the biggest revelations came years later as we gradually started to educate ourselves on low temperature heating: our system as a whole was never designed to work properly with a heat pump. Instead, it was slapped in to run like a boiler. This critical error was evident from the start, but we didn’t know enough then to question it.

The heating services and operations engineer from Global Energy Systems commissioned our system to run on a 45°C set point – a decision that is utterly indefensible if you understand how heat pumps should work. Heat pumps are designed to operate most efficiently at lower flow temperatures: the higher the flow temperature, the more energy they consume, driving up costs and eroding efficiency. Shockingly, when we inquired about weather compensation – a feature that optimises system performance by adjusting flow temperatures based on outdoor conditions – Global Energy Systems outright denied that their heat pump had this capability.

This was a blatant lie. Years later, after tinkering with the control panel, we discovered weather compensation settings and heat curve adjustments buried in the system. Global Energy Systems, it seems, had deliberately chosen to run the system at a fixed 45°C, not for our benefit, but to mask deeper issues with the system’s design and performance.

As we learned more about heat pumps, we suspected that a proper heat loss calculation and heating design had never been done. When we confronted Global Energy Systems, they admitted it hadn’t. This was a massive blunder. Proper heat loss calculations are the cornerstone of any heat pump installation. Without them, you’re essentially flying blind, which explains the inadequacies of our system.

The Saga of Cold Rooms and Circulation Pumps

For years, cold spells exposed more limitations of our system. The north end of our house – where the index circuit is – struggled to exceeded 16°C when outdoor temperatures dropped below 3°C. Global Energy Systems' solution? Add more or upsize circulation pumps. We now have four, and they haven’t resolved the problem. Instead, they’ve increased our running costs.

When we had our system evaluated by some of the UK’s top installers, their feedback was unanimous: the system had no design and was set up to fail. As Ken Bone explains in the video below, it was essentially running as a boiler replacement with a Delta-T of 20, littered with on/off stats, which is unsuitable for a heat pump. Our house as a whole never had a chance of being heated efficiently.

Lessons Learned

Insist on a Proper System Design

Before installation, double, triple and quadruple-check that your system is designed properly. Ensure every room and heat emitter can hit its target temperature (19°C, 20°C or 21°C, depending on your preference). Get this in writing. These temperatures must be achievable when running weather compensation. Don’t let your installer convince you to settle for a fixed flow temperature. In mild months, this approach wastes energy and money.

Understand the Importance of Controllers

Heat pumps are fundamentally all very similar at their core: a metal box with pipes, refrigerant and a compressor. The controller, however, is what determines how effectively the system runs and does what you want it to do. In our case, the controller from Global Energy Systems has been dreadful. As we have a hybrid system, it can’t even run weather compensation if we wanted to use the boiler as a redundancy. Below 0°C, we’d have to manually turn the boiler on, which defeats the purpose of automation. There’s no scheduling. Frankly, there’s a lot missing. Opt for a brand that has a good controller.

Know Your Warranty Terms

Many warranties are tied to annual servicing. In our case, as per the warranty document, only Global Energy Systems could service the unit for the warranty to remain valid. This wasn’t communicated clearly upfront, leaving us at the mercy of the manufacturer. In addition to this, our unit came with a paltry three year warranty. Always ask about warranty terms and ensure you’re comfortable with them before committing. If something goes wrong, replacement components can be costly, so you have to ensure you’re covered for the longest time possible.

Look for Free Remote Monitoring Options From the Manufacturer

Global Energy Systems provided a three-year remote monitoring service via 4g, which allowed them to diagnose issues remotely. After that, they charge an annual fee. In contrast, some manufacturers like Mitsubishi offer free remote connectivity and telephone support for diagnosing problems. Check if your chosen manufacturer includes this service without additional charges. I’d also recommend that this connection is done via WiFi.

Don’t Settle for Less

If something feels off, don’t make excuses. We convinced ourselves that our system was working fine when it clearly wasn’t. Heat pumps, when installed correctly, keep you warm and comfortable. Don’t settle for anything less.

A Cautionary Tale with a Purpose

Despite our experience, we believe heat pumps are an amazing technology and the future of heating. They can deliver efficient, eco-friendly heating when installed correctly.

Our frustrations and lessons ultimately led to the creation of Renewable Heating Hub and writing two books: Bodge Buster and From Zero to Heat Pump Hero. Without our subpar installation and 2.7 SCOP system, these resource for homeowners wouldn’t exist. Now, we’re on a mission to educate others and help them avoid the mistakes we made.

Final Advice

1. Take your time: Investigate and question everything your installer says. If you’re unsure, leave a question on our forums.
2. Research thoroughly: Visit completed projects, speak to previous clients and understand the design process.
3. Demand transparency: Don’t accept vague answers. Insist on clarity about system design, warranty terms, controls and monitoring options.
4. Don’t let anyone rush you into a decision: A properly designed and installed system will keep you warm, save you money and reduce your carbon footprint.