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Don’t Install a Heat Pump Until You Read This

Mars · 2024-12-15T22:36:31Z

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 th...

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Air Source Heat Pumps (ASHPs)

Last Post by Mike Patrick 3 months ago

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Mars

(@editor)

Illustrious Member Admin

Joined: 6 years ago

Posts: 4807

Topic starter 09/05/2026 4:42 pm

For those that have followed our heat pump journey here are two more videos on on our heat pump, and there are a lot of lessons to take away.

First up, this video covers our early optimism, the documentation gaps, the missing heat loss calculations, the fixed 45C flow temperature, no weather compensation and the repeated winter frustration.

New to heat pumps? Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
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Mars

(@editor)

Illustrious Member Admin

Joined: 6 years ago

Posts: 4807

Topic starter 09/05/2026 4:45 pm

In our latest update, we attempt to show what a poor heat pump system comprises of... from undersized pipework choking flow… to a buffer tank killing efficiency… to control strategies that made absolutely no sense for a heat pump…

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Mike Patrick

(@mike-patrick)

Reputable Member Member

Joined: 5 years ago

Posts: 196

11/05/2026 2:28 pm

Mars, This is a really informative video. End users such as yourself and many others on this forum really should not have had to gain this level of understanding of ASHP systems, to make up for the inadequacies of so called professionals, in order to make informed buying decisions.
We have about 10m of underground pipework from the ASHP to the house.
Like you, it's the one aspect of our installation that I've never looked at but have often wondered, does the core of our problems lie underground. Like the person who has a lot of debts and thinks that if they don't open the final demand letters coming through the letterbox then the problem will go away. Or it's Schrodinger's Cat. Until I actually take a look, the pipework is in a superposition of two states, good and bad existing at the same time.
After seeing your video I am resolved to dig up a section of our pipework this summer to see how it is. Where it goes into the ground by the ASHP it looks OK, but what will I find beyond? In our case, the house end of the pipe comes up under the kitchen floor through the floor slab that was put down during the renovation. If the news is bad we will have to re-route it to come through the wall to connect with the internal pipework.
Having recently had to decide whether to repair or replace our broken heat pump I'm even more glad that I have gone for repair. It wouldn't make sense to do any replacement without investigating that underground pipe first.
Mike

This post was modified 3 months ago by Mars

Grant Aerona HPID10 10kWh ASHP

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