I'm an office administrator for a 120-person company. I manage maintenance and facilities purchasing—roughly $150,000 a year across eight or nine vendors, depending on the season. I report to both operations and finance, which means I hear about a problem twice: once when the equipment breaks, and again when the invoice lands.

If you've ever had to fix a Vaillant conventional boiler, replace a Vaillant ecoTEC Pro 28 expansion vessel, or explain why the office Samsung fridge is cold in the freezer but warm in the fridge, you know there isn't one clean answer. There are scenarios. This is how I sort them.

Of the 60–80 maintenance orders I place every year, maybe a third are reactive repairs. The rest are planned services. The reactive ones are where I make mistakes. That's why I stopped looking for a single provider who can 'do everything' and started matching the problem to the right specialist.

The three scenarios that show up on my desk

After five years of buying these repairs, most situations fall into one of three buckets. The important thing isn't just the brand. It's whether the problem is in one sealed system, one component, or a broader multi-trade contract.

  • A heating fault specific to one boiler model, like a Vaillant conventional boiler.
  • A refrigeration fault that leaves the freezer working but the fridge not cooling.
  • A maintenance decision that bundles heating, compressed air, and general handyman work.

Each bucket points to a different kind of vendor. Let me walk through them.

Scenario A: Your Vaillant conventional boiler throws a fault code or keeps losing pressure

The call that taught me the most started with a pressure gauge. The boiler was a Vaillant ecoTEC Pro 28, but the scenario applies to any gas boiler—including a Vaillant conventional boiler with a separate hot water cylinder.

The Vaillant ecoTEC Pro 28 expansion vessel is a common failure point. An expansion vessel is the small steel tank that absorbs the extra volume of water when it heats up. If the internal bladder loses its air charge, the tank can't do its job. Water expands, pressure rises, and the boiler either vents through the pressure relief valve or locks out. It can look like a major boiler failure when it's actually a service part.

Most buyers focus on the boiler itself and completely miss the expansion vessel. The question everyone asks is 'what's the fault code?' The question they should ask is 'what was the vessel's pre-charge set to?'

The manual for our Vaillant ecoTEC Pro 28 expansion vessel says the pre-charge should be checked during servicing. It doesn't happen automatically. When the repair was done, the engineer re-pressurised the vessel to the cold fill pressure, checked the whole circuit, and explained that the fault code was a symptom, not the problem.

I wanted to use a general facilities company for this because they were cheaper. They said they handled 'all heating systems.' But when I asked which manufacturer certifications their engineers held, the answer got vague. I kept the Vaillant-accredited heating firm instead. The specialist said, 'this is straightforward for us, but if it was a cooling fault on the Samsung fridge, you'd need a different tech.' That boundary is exactly what I want.

The same logic applies to a gas-fired heater. If a vendor says they can service heaters, they should be able to show you the right registration. Don't accept 'we know a guy.'

Scenario B: Why is my Samsung fridge not cooling but freezer works?

This exact question shows up in our maintenance request portal more than I'd like to admit. Our break-room Samsung started doing it last year. The freezer was keeping ice cream hard, but the fridge section was sitting around 14°C. That's not okay for food.

Before you replace a Samsung fridge, know the usual reasons:

  • Evaporator fan motor failure. The fan that moves cold air from the freezer into the fridge stops turning. The freezer stays cold; the fridge doesn't.
  • Defrost heater failure. If the defrost heater doesn't melt frost off the evaporator coil, ice builds up and blocks airflow. The freezer can still stay cold while the fridge gets warmer.
  • Damper or air flap stuck closed. Less common, but it's a cheap fix if that's all it is.

What catches people off guard is how often the compressor is fine. The fridge isn't broken in the dramatic sense. It's a fan, a heater, or a flap problem. You'd think a half-cold fridge would need a new compressor, but usually it doesn't.

I called an appliance repair specialist rather than the boiler engineer. The technician found a failed evaporator fan motor. The repair was about $260. A new fridge would have been over $1,200. After I approved the repair, I kept second-guessing. What if the diagnosis was wrong? The week until the part arrived was stressful. When the tech came back, measured 3°C in the fridge, and the freezer still hit -18°C, I relaxed.

One thing I do not compromise on: if the repair involves breaking into the sealed refrigerant circuit, the person doing it should be F-Gas certified. In Europe, that's required under EU Regulation 517/2014. A general handyman has no business opening that system.

Scenario C: Bundling air compressor and heater maintenance into one contract

This is where I've made my most expensive mistake. In 2020, I tried to consolidate heating, cooling, a small workshop air compressor, and general maintenance into one facilities vendor. The pitch sounded great: one invoice, one contact, one accountable partner. The reality was a generalist dispatcher subcontracting most of the work. The most frustrating part of that setup wasn't the price. It was the follow-up. You'd think one vendor would mean fewer calls, but I ended up chasing two subcontractors and three invoices.

An air compressor is a good test. It isn't a boiler. It isn't a fridge. It has its own filters, oil, pressure switch, and receiver tank. A boiler engineer is not necessarily qualified to service a compressor. A refrigeration tech is not an air compressor tech. Those are separate trades.

When I asked the bundled vendor who would service the compressor, the answer was 'our local partner.' When I asked who that was and what they were certified to do, the answer got vaguer. That's when I stopped consolidating.

The line that changed my thinking came from a different vendor: 'This isn't our strength. Here's who does it better.' That vendor didn't lose my trust. They earned more of it. If you ask me, a supplier who can say that is more credible than one who promises to handle everything.

The same logic applies to a heater. A gas-fired heater and an electric heater have different failure modes. A water heater has its own safety controls. I want someone who knows the specific type, not someone who will 'send a guy from the shop.'

That's not an argument against generalists in every case. For a very small office with simple equipment, a good generalist can make sense. But for a building with a Vaillant boiler, a Samsung fridge, and a workshop air compressor, I'd keep a specialist list.

How to tell which scenario you're in

If you're staring at a fault code and a pressure gauge, that's Scenario A. If the freezer is cold and the fridge is warm, that's Scenario B. If you're comparing a bundled maintenance quote and can't tell who'll actually show up, that's Scenario C.

From there, ask three questions:

  1. Is the problem isolated to one machine? If yes, call a specialist for that machine. For a Vaillant conventional boiler, that's a gas heating engineer. For a Samsung fridge, it's an appliance repair tech. For a workshop air compressor, it's a compressed air service company.
  2. Does the job involve gas, refrigerant, or pressure vessels? Those are regulated for a reason. Don't let a general handyman touch them.
  3. Is the repair quote more than half the replacement cost? If yes, start the replacement conversation—but factor in the unit's age. Last year, we spent around £620 repairing a five-year-old Vaillant when a new equivalent plus installation was roughly £2,800. That repair made sense. If it had been a 14-year-old boiler, I'd have replaced it.

The bottom line

There isn't one right answer for a Vaillant conventional boiler, a Samsung fridge, or an air compressor. But there's usually a right category of vendor. If the equipment has one manufacturer and a specific fault code, or if the job needs gas, refrigerant, or pressure vessel skills, that's a specialist job.

Does that mean never use a generalist? No. It means ask better questions before you hand them the work. If they can tell you exactly which engineer will show up, which certifications they hold, and what they do when it's outside their wheelhouse, they're worth considering.

The best part of getting this sorted: the facilities team stopped guessing who to call. Our maintenance request portal now has separate vendor lists for heating, refrigeration, and compressed air. I don't get panic emails at 8am asking whether we can still use the fridge.

Personally, I'd rather work with a specialist who knows their limits than a generalist who overpromises. That's also the kind of vendor I trust with the next weird equipment problem—including the next time someone asks me why the Samsung fridge is not cooling but the freezer works.