Early in my career in Glasgow, I got a call about lukewarm hot water. The customer was convinced it was the thermostat - a simple fix, in and out in an hour. It wasn't the thermostat. It was a pinholed coil inside the cylinder, silently leaking heat into the central heating circuit for who knows how long. By the time I got there, the cylinder was done, the pipework needed a full upgrade to meet current standards, and what looked like an hour's job turned into several hours of work and a bill the customer hadn't budgeted for. A limescale filter - fitted years earlier, cost next to nothing - would almost certainly have prevented it.
That job stuck with me. Not because it was the most complex thing I've ever done, but because it taught me something I've carried ever since: the symptom a customer describes and the problem that actually exists are often separated by a significant gap. And the gap is almost always more expensive the longer it goes unexamined.
What heating systems taught me about houses
I spent the better part of a decade working across Glasgow and throughout Yorkshire and the Midlands, with gas heating, hot water systems, and pipework making up the core of the work. The UK housing stock is old and layered, and the heating systems in it are a story of thirty years of half-measures, DIY interventions, and regulations that changed faster than anyone upgraded their kit.
What gas and plumbing work teaches you, faster than almost anything else, is that a house is a system. The hot water cylinder talks to the boiler talks to the radiators talks to the pipework buried in the walls and under the floors. A fault in one place shows up as a symptom somewhere else entirely. The customer who rings about lukewarm water might actually have a pump issue, a zone valve that's failing, an airlock, a coil that's been slowly corroding for years. You don't know until you look at the whole picture.
"The symptom is never the whole story. It's just where the story becomes visible."
This is the mindset that seventeen years builds - not a checklist, but a way of thinking. You learn to follow the system, not just respond to the presenting complaint. And you learn that the most expensive jobs are almost always the ones where someone responded to the symptom for years without ever addressing the cause.
The job you're called for and the job that needs doing are often different things. Diagnosing correctly costs a little time upfront. Getting it wrong costs a lot more later. A good tradesman tells you what they found - not just what you asked them to fix.
Limescale, corrosion, and the cost of doing nothing
Hard water is the silent enemy of every hot water and heating system in the UK, and in parts of New Zealand too. Limescale builds up inside cylinders, on heating elements, inside heat exchangers, and along pipework - slowly, invisibly, until efficiency drops enough that you notice, or until something fails outright.
The pinholed coil job was a textbook example. Limescale had built up inside the cylinder over years, accelerating the corrosion of the coil until it finally gave way. The repair cost - new cylinder, new pipework, compliance upgrades - was many times what a scale filter and annual service would have run. This is not an unusual ratio. In heating and hot water work, preventive maintenance almost always wins on cost, and almost nobody does it until something goes wrong.
I saw this pattern constantly in Glasgow. Boilers running well past their service intervals, cylinders that hadn't been checked in a decade, pressure relief valves that had been dripping quietly for so long the owner had stopped noticing. None of it dramatic. All of it gradually building toward a job that would eventually be unavoidable - and significantly more expensive for having been deferred.
Preventive maintenance on heating and hot water systems pays for itself, usually several times over. An annual service, a limescale filter in hard water areas, a cylinder check every few years - these are cheap. Replacing what they protect is not.
NZ systems: familiar logic, different vocabulary
Moving to New Zealand in late 2024, I expected the heating and hot water systems to feel foreign. In some ways they do - wetbacks, heat pumps doing the work that radiators do in the UK, hot water cylinders often in the ceiling instead of an airing cupboard, and a regulatory environment that's evolved separately from the UK's Gas Safe framework.
But the underlying logic is identical. A cylinder that hasn't been checked in years is a cylinder that's working toward a problem. A hot water system with no filtration in a hard water area is building up scale right now, today, whether the owner knows it or not. A gas appliance that runs fine most of the time but occasionally does something slightly odd is telling you something - and it's worth listening to before it says it more loudly.
The other thing that travels is the pattern of deferred maintenance. NZ homeowners, like UK homeowners, tend to look after the visible stuff - the paint, the garden, the kitchen - and leave the mechanical systems to run until they don't. Which is completely understandable. You can't see what's happening inside a cylinder or a heat exchanger. Out of sight, out of mind, until it isn't.
The systems you can't see are the ones most worth checking. Hot water cylinders, heating pipework, gas appliances - they give you very little warning when they decide to fail. A periodic check by someone who knows what they're looking at is cheap compared to the alternative.
What I actually listen for
When I walk into a house now, the heating and hot water system is one of the first things I orient to. Not because I'm looking for problems - most of the time there aren't any - but because it tells you a lot about how the house has been looked after overall.
A boiler that's been serviced regularly, a cylinder that's the right age and properly lagged, pipework that's been done properly and isn't showing signs of weeping joints or corrosion - these things tell you that someone has been paying attention. The reverse tells you something too.
The specific things I notice: water pressure that's lower than it should be (often the first sign of a partial blockage or a failing pressure regulator), hot water that takes noticeably longer to arrive at the tap than it used to, a cylinder that's warm on the outside in places it shouldn't be. And if you ever smell gas or combustion fumes in a room with a gas appliance - that's not a "worth a conversation" situation, that's evacuate the building and call the gas emergency line immediately. Some things don't wait.
A heating engineer has to be good at almost every trade - and that shapes how you see everything else. To do the job properly, you lift floors and refit them. You remove doors to swap a cylinder and rehang them perfectly. You chase pipes into walls, then plaster and paint over them. You hang radiators millimetre-perfect to existing pipework with new brackets. You wire up complex system controls. You work in every corner of a house, in every material. Seventeen years of that builds a broad set of skills - and a habit of thinking about the whole job, not just your part of it.
Why any of this matters to you
Heating engineers have a reputation - deserved - for being the most multi-trade person on any job. You can't just do the pipework. You lift the floors to get to it, and refit them properly when you're done. You shift the furniture, remove the skirting, chase the wall, plaster it back, touch up the paint. You rehang the door you had to take off to get the new cylinder in. You commission the controls and explain them to the owner. By the end of a big heating job you've touched carpentry, plastering, painting, electrical, and plumbing - and every bit of it has to be right.
That background is, I think, what makes a good heating engineer transition naturally into broader trade work. You've already spent years thinking about the whole job. You're already used to leaving a house tidier than you found it. You already know that the visible finish - the straight skirting, the clean plaster line, the door that swings true - matters as much to the customer as the thing they called you in for.
You don't need to understand how a hot water cylinder works to look after one. You just need to know roughly how old it is, when it was last checked, and whether anything about your hot water or heating has changed subtly in the last year. Slower to heat up. Pressure not quite what it was. A noise that wasn't there before. These things are easy to ignore - until they aren't.
That's what seventeen years has taught me more than anything: the cost of a problem and the cost of ignoring it are very different numbers, and the difference grows every year you leave it.
Something not quite right with your hot water or heating?
Drop us a note about what you're seeing - and where you're based. We'll tell you what we think it might be, and whether it's something we can help with.
Get in touch →Need a hand with something?
I'm touring New Zealand doing handyman work town by town. If you've got a job that needs doing, drop me a line and I'll let you know when I'm in your area.
Get in touch