If you manage an office, someone will eventually ask you 'what is a boiler?' Not because they want an engineering lecture. Actually, they want to know whether the new Vaillant quote makes sense, why that electric heater in a meeting room isn't enough, and whether the bladeless fan your colleague bought is a real solution or a desk toy. I've been on both sides of that question since 2020, when I took over purchasing for a 40-person company.
I'm not a heating engineer. I'm an office administrator who manages facilities buying, maintenance orders, and the occasional cold-building emergency. I manage roughly £38,000 a year of facilities spending across six vendors, and I report to operations and finance. So when I compare boilers and electric heaters, I look at them the way you would: cost, disruption, complaints, and whether finance will reject the invoice.
Basically, it comes down to four things: what the system costs over its life, who can safely install and repair it, whether it actually keeps a building warm, and what the maintenance chaos looks like when something breaks.
What Is a Boiler, in Buyer Terms
A boiler heats water and pushes it through radiators or underfloor pipes. That water does the heating, not the boiler itself. A heat pump like the Vaillant Arotherm Plus 15 kW does the same job, but it captures heat from outside air instead of burning gas. An electric heater, including a fancy bladeless fan, heats the air right in front of it. That difference changes every other comparison.
From the outside, a boiler and an electric heater both look like ways to make a cold room comfortable. The reality is they solve completely different problems.
If you only need one meeting room warm for three hours, an electric heater can be the right answer. If you need a whole office warm at 9 am on a Monday, you need a system that heats the building, not the person sitting nearest to the plug.
Dimension 1: Upfront Cost vs Long-Term Running Cost
The first question everyone asks is 'How much is it?' But for an admin buyer, the real question is what the system costs across its working life.
In my experience, a new Vaillant boiler and installation in London sits around £2,500 to £4,500, depending on the pipework, controls, and how much of the building needs to be opened up. A basic electric heater can cost £40. A good bladeless fan heater might cost £150 to £300 (prices based on major online retailer quotes as of January 2025; verify current rates). That difference looks massive until you run the numbers.
Electricity costs roughly three times as much as gas per unit of heat in the UK (Source: Energy Saving Trust, 2024). So a direct electric heater that runs all day in a large space will quickly overtake a gas boiler's fuel bill. A heat pump changes that maths, because it uses electricity to move heat instead of creating it. The Vaillant Arotherm Plus 15 kW, for example, can deliver significantly more heat than the electrical power it pulls. But that only happens if the building is insulated and the system is designed correctly. Slap a heat pump on a leaky office and you'll get a big electricity bill and a nice case study for the installer.
Honestly, I considered buying six electric heaters for a satellite office. The upside was roughly £1,200 total. The risk was cold mornings, staff complaints, and a building that never fully felt dry. I kept asking myself: is £1,200 worth potentially explaining to the operations director why the office is 15°C? The answer was no.
Conclusion: The electric heater is cheaper to buy. The boiler (or heat pump) is cheaper to run. If you're heating a whole building, running cost wins.
Dimension 2: Who Can Install and Repair It?
Boilers and heat pumps are not plug-and-play. Gas boilers in the UK can only be worked on by Gas Safe Registered engineers. According to Gas Safe Register (gassaferegister.co.uk, accessed January 2025), anyone who works on gas appliances without registration is breaking the law and putting people at risk. That's not a minor detail. It's the first thing I check when I search for Vaillant boiler repair London. If the engineer doesn't have the right credentials, I don't care how cheap the callout is.
Heat pumps usually need a trained installer too, and in the UK you'll often see MCS certification mentioned because it's linked to government incentives. Electric heaters, by comparison, seem easier: plug it in and press the button. But if you're hardwiring multiple heaters or changing electrical circuits, you'll still want a qualified electrician. The 'no installation needed' story starts to fall apart when you need three 16-amp circuits.
This is also where I've changed my opinion about suppliers. I used to prefer companies that said 'we do everything.' Now I'd rather work with a specialist who knows their limits than a generalist who overpromises. The heating engineer who told me 'this isn't our strength—here's a better specialist for your heat pump controls' earned my trust for all the boiler work. There's a reason we now send most of our maintenance work to one firm: they're clear about what they don't do.
Conclusion: The safest option depends on who's available to maintain it. A boiler is only reliable if you have a reliable, registered repair path for it. That matters more than the brand.
Dimension 3: Comfort, Consistency, and the Bladeless Fan Trap
This is the dimension I almost ignored, and it cost me.
A boiler heats water. That water sits in radiators and holds heat even when the burner switches off. The room temperature stays fairly steady. An electric heater heats air directly, but the moment you switch it off, the heat disappears. A bladeless fan heater does this job very well for one person. Put it in a 40-square-metre meeting room and you'll experience the exact moment when the thermostat says 18°C but everyone's still wearing coats. That's kind of the trap.
Never expected that. The surprise wasn't the price difference. It was how quickly the office got cold when the only heat source was a small electric fan. People don't complain about the heater's wattage. They complain that their hands are cold while the heater is blowing hot air past them.
This is where the Vaillant Arotherm Plus 15 kW sits differently from both. It's an air-to-water heat pump, so it works with radiators or underfloor heating, just like a boiler. It's not a giant fan heater. A well-designed heat pump delivers lower-temperature heat for longer periods, which can feel steadier than a boiler's stop-start heat. But it only works if the building was sized for it. A 15 kW unit is not automatically the right unit for a building that currently has a 40 kW boiler.
Conclusion: Instant warm air feels nice right now. Consistent building heat is what makes an office usable. These are not the same thing.
Dimension 4: Repairs, Maintenance, and the Costs That Hide Until February
Last winter, we had a Vaillant boiler in a London office that kept losing pressure. The display showed an F22 fault code. According to Vaillant's fault code information, F22 means low water pressure, and it often just needs the system re-pressurised. But because I hadn't asked the service engineer to show me how to do it, we paid a £120 callout for a 15-minute fix.
I still kick myself for that one. If I'd spent five minutes learning the right way to re-pressurise the system, the office would have been warm the same morning. But the other lesson was useful: good Vaillant boiler repair London doesn't need to be expensive if you have a maintenance contract and an engineer who knows the product line.
Electric heaters have no circulation pump and no pressure gauge. You don't service them. You just replace them when they break. That sounds like a blessing until you realise you're managing a growing pile of cheap appliances, extension leads, and 'why is this one not working' complaints. I'd rather pay for an annual boiler service than spend a Tuesday morning testing nine different plug-in heaters.
Conclusion: A proprietary system needs maintenance, and maintenance can annoy you. But scattered electric heaters come with their own quiet chaos, and they don't heat the building any better.
So Which One Should You Choose?
If you're replacing an existing gas boiler in a building with radiators and a normal gas supply, a well-maintained Vaillant boiler is usually the lowest-disruption choice. That's not a sexy answer. It's a practical one.
If you're trying to heat a small, sporadically used space with no gas supply, an electric heater is fine. Just don't treat it as a central heating strategy. A bladeless fan heater can be brilliant for one person. It is not a boiler replacement by itself.
If you're thinking about moving away from gas, the Vaillant Arotherm Plus 15 kW is worth looking at. But it's not a drop-in swap for any old boiler. You need heat-loss calculations, proper installation, and someone who'll explain where the back-up heater is and how the controls work. Find an installer who says what they won't do, not one who says yes to everything.
My own rule is simple: buy the best central system you can justify, maintain it properly, and use electric heaters only as top-ups for desperate afternoons. That's worked for us since 2021, and it's saved more arguments than I can count.