I recently completed the Heat Geek Mastery course, partly out of personal interest, partly out of necessity. Running Renewable Heating Hub, speaking to manufacturers, interviewing engineers and engaging with thousands of homeowners on the forums puts me in daily contact with the complexities and disputes of the heat pump world.

I wanted to deepen my understanding so I could engage meaningfully with engineers, challenge poor practice, interpret the jargon and ultimately give homeowners more accurate guidance. From that perspective, the course did exactly what I hoped it would. I now understand the theory of heating systems and heat pumps at a level I didn’t expect, including maths that at times felt designed to expose my limits.

I can read a radiator schedule. I can understand pump curves, delta T, emitter output tables, frictional resistance, DT5 versus DT10 design assumptions and the implications of flow temperature on efficiency. I can look at a system and roughly understand why something is performing well or why it’s not. But after all of that, there’s one glaring truth that needs to be said plainly: even after completing one of the most theoretical and structured courses available, I still have absolutely no idea how to actually install a heat pump.

What the course gave me is knowledge. What it could never give me is competence.

The installation of a heat pump is not just a theoretical exercise, nor is it a single skillset. It is the convergence of multiple trades, each of which has its own depth, its own technical culture and its own ways of going disastrously wrong. Even if a person mastered the Heat Geek content, plus the basic Level 3 heat pump qualification, plus a wiring course, plus the usual plumbing prerequisites, they still wouldn’t necessarily be capable of installing a heat pump to a high standard. Because the reality is this: heat pump installation demands an unusual combination of theoretical discipline, practical skill, experience, judgement, patience and, frankly, humility. And almost no one has all of those things at once.

The plumbing element alone requires years of experience to do well. Achieving clean, tidy pipework that is both functional and aesthetically respectable is a craft in itself. Poor pipe routing can restrict flow, create noise or starve emitters within a system. Lift the lid on the majority of failing systems and somewhere in the bowels of the installation you’ll find a poor plumbing decision: a lazy connection, a kinked pipe, a badly sized pump, an unnecessary buffer or low-loss header that destroys the system’s efficiency. The pipework is literally the bloodstream of a system. You can know all the theory in the world, but if you can’t physically execute it, you cannot produce a good installation.

Then there’s electrics. Controls wiring on a heat pump installation is not glamorous, but it’s absolutely critical. If you mis-wire a sensor, misinterpret a terminal or fail to integrate correctly with a cylinder stat, mixing valve or third-party controller, the system can behave unpredictably, short cycle, refuse to defrost correctly or, in some cases, not function at all. We've witnessed this firsthand on our system. This requires proper electrical knowledge, not just the ability to follow a schematic, but the ability to interpret a manufacturer’s quirks, understand relay logic, fault-find under pressure and correct mistakes without making more of them.

And then we get to the theory. This is the part that most people outside the industry underestimate, and the part that many inside the industry like to quietly ignore. A good heat pump installation is fundamentally a design exercise. It requires accurate heat loss calculations, appropriate emitter sizing, correct pump and pipe sizing, a flow temperature target that is realistic and a design margin that allows the system to function in real, messy life, not just in neat spreadsheets.

The Heat Geek course makes the theory accessible. But knowing the formula for emitter output at different delta Ts and actually applying it in a Victorian terrace with unknown insulation, mislabelled pipework, unbalanced radiators and rooms that behave completely differently than the design suggests, these are two very different worlds.

I now understand why good installers are constantly balancing theory with reality. They aren’t “forgetting the maths,” nor are they blindly obeying it. They are interpreting it, through experience, judgement and, sometimes, creative compromise. The best installers have a feel for a building, a sense of how it will behave in extreme weather, an intuition for where the pinch points are, which parts of the design matter most, and where you can safely flex. That only comes from doing it. It does not come from any online course, no matter how good the teaching. These are the installers that we are trying to find on a daily basis so that they can be added to our recommended installer list.

At the opposite end of the spectrum, theory without discipline becomes dangerous. We lived this ourselves recently. We had an installer who waved away theory as if it were optional, who believed you could “figure it out on site,” who relied on guesswork and gut feeling and did not respect what the numbers (or our house) were trying to tell him. That approach didn’t result in a quirky fix for our heat pump; it resulted in a broken system. He didn’t just get the design wrong, he physically damaged the heat pump, disrupted the hydraulic integrity of the system and turned a functional home into a project of diagnosis and repair. That experience is not rare. The forums are filled with variations of the same story.

And this is why choosing an installer is a minefield. Because you are not just choosing a tradesperson; you are selecting a rare hybrid of engineer, plumber, electrician, designer, counsellor and sometimes detective. And you are trusting them with something that has hundreds of potential failure points, any one of which can compromise performance, efficiency and comfort.

This is why we created the Recommended Installer Network. Not because we claim to have a perfect list (such a thing will never exist) but because we’re trying to identify the installers who consistently blend theory with real-world application, who design properly, install carefully, commission meticulously and, perhaps most importantly, take responsibility when things go wrong. Because things do go wrong. A heat pump install has a million places where something can go sideways. What matters is how an installer responds when it does.

The majority of the installers we bring into the network are the ones who show a pattern of thinking, not a pattern of perfection. They study. They improve. They ask questions. They turn up to fix their mistakes. They don’t disappear when a system throws an error code that the manufacturer’s manual hasn’t documented. They don’t dodge phone calls, deny problems or blame homeowners. They behave like professionals. And it is astounding how rare that combination really is.

So completing the Heat Geek Mastery course was valuable. It has transformed the way I think about heating systems, question assumptions and support homeowners. It has also given me an appreciation for the sheer complexity of doing this work properly. It has made me more sympathetic towards the good installers, more wary of the careless ones and more convinced that homeowners need help navigating this industry. Because the gap between theory and practice is a chasm, and falling through it can cost a homeowner thousands of pounds, years of frustration and a deep mistrust of a technology that can work brilliantly when done right.

So am I now a certified heat pump installer? Of course not. But I am better equipped to spot good practice, call out poor practice, ask the right questions and help guide homeowners towards the people who can deliver systems that actually work. And in an industry where the smallest mistake can undermine the biggest investment, that feels worth the effort.