I had a new boiler installed for winter and it was so much easier than I expected
My old combi was struggling so BOXT swapped it for a beefy new Worcester Bosch in just five hours
If there’s one thing I’ve learned as I’ve gotten older, it’s that British winters aren’t just “a bit nippy” any more – they’re bloody expensive. As gas prices continue to rise and the cost-of-living squeezes every last drop out of your bank balance, a healthy boiler suddenly feels like a big deal.
Thankfully, my old boiler wasn’t too old and was performing the basics okay, although it never quite kept up with the house. I live in a three-bed home and it always felt like the boiler was slightly underpowered. Two people couldn’t shower at the same time without the pressure and temperature dropping, and if I jumped in the shower straight after someone else, the pressure would slump and I’d have to wait a good ten minutes for it to recover. The radiators took ages to warm up from cold, too, and while it wasn’t a dealbreaker, the hot water from the taps always felt like forever to come through, which didn’t help with water wastage. None of that was exactly ideal when trying to keep heating use sensible and only whack it on when you really need it.
Here’s how the whole thing went, from ordering online to banging the heating back on and getting all cosy again.
Boxt boiler experience: Super easy to order
Just like with my air con install, everything kicked off on boxt.co.uk, this time via the boiler section. I started by getting a fixed price quote, which required me to answer a series of questions about my home, such as how many bedrooms and bathrooms, what the current boiler is, where it lives, whether I had a hot water tank, what the flue situation looks like, and so on. It’s all very clear, with diagrams and simple explanations, so you’re not guessing your way through any plumbing jargon.
In my case, I already had a combi in an upstairs airing cupboard on the landing, feeding a three-bed house with one main bathroom, an ensuite and a downstairs loo. I flagged that the existing flue run was long - roughly five metres – because it travels horizontally from the cupboard, across the landing, through the loft above the bathroom and then out of the wall at the back of the house. Since the flue terminal was located two-floors high above my outbuilding, scaffolding was already required in fitting the new one. That’s the sort of thing I worried would cause the most problems or make the price soar, but it was simply factored into the quote and didn’t seem to make much of a difference to the overall cost.
The boiler BOXT recommended for my setup was the Worcester Bosch Greenstar 8000+ Style 32kW, in gloss black. It’s one of the most powerful wall-hung combis available to me, and is designed to cope with multiple showers running and big radiator counts without making a fuss. Behind the shiny front it touts about 30.2kW for central heating output and a flow rate of up to 13.7 litres per minute – a definite level up from my old 25kW boiler, which offered a flow rate of 10.2 litres per minute and a central heating output of 24kW.
The main thing I was made aware of during this quote was that it’s also built to be more efficient. BOXT explained that the higher hot water flow rate is what helps keep showers feeling strong and consistent, even when more than one person is using water, and the extra heating output is what lets all the radiators come up to temperature faster. Due to the 8000+ has more headroom, it shouldn’t need to run as close to its limit to heat the house either, which should, in theory, be kinder to the boiler over time. This, I was hoping, would help put me in a better position to keep bills under control than with an older or undersized unit.
The fixed price for everything – the boiler, all the parts, the new extended flue, a chemical system flush, magnetic filter, CO alarm, labour, removal of the old boiler and all the paperwork – came out at £4,249. It’s by no means pocket change, but it was almost £2,000 cheaper than the quote I received from British Gas. And at least there were no hidden “oh by the way” extras, as the quote clearly listed everything being done, including the extra flue length and a bunch of components that help protect the boiler long-term (like inhibitor chemicals and a shock arrestor for homes on water meters).
Once I confirmed the order, I added the details to the BOXT app so I could track everything in one place. As with the AC install, they asked me to upload photos of the current boiler, the flue route and the general area they’d be working in. The tech team then checked it all over behind the scenes so they could confirm everything with me before install day. This included letting me know that I’d need my entire flue replacing for a new one, despite the old one not being that old (regulations mean you can’t just reuse an old one with a new boiler). I won’t lie, I was pretty concerned this would cause quite a bit of damage to the new paint work I’d only just done on the stairs, so wasn’t looking forward to redoing all of that after installation.
Speaking of, this was the last step, to choose which day would suit me best. Quite shockingly, I could have had it fitted the very next day if I’d wanted to (although this would have come at an extra cost) but good to know if, for example, I’d needed an emergency replacement. I wasn’t in crisis mode, so I went for a date the following week instead, to give myself time to clear the airing cupboard and brace for the disruption I was expecting.
Boxt boiler experience: Installation done in time for lunch
Two or so evenings before install day, the BOXT engineer and his apprentice visited me as a courtesy to introduce themselves, and to have a look at the job IRL so they’d be prepared for the installation. They walked me through exactly what they’d be doing, explaining how the old boiler would come out, and that the entire flue run would be replaced with the system also getting a chemical flush alongside a new filter and shock arrestor, adding that everything would be tested before they left. I really appreciated this as it reassured me they knew what they were doing and I could trust them with, what is essentially, the beating heart of my home.
When install day came around, the engineers arrived at my gaff around 7:30am to prepare for the job. The new boiler – with all the necessary flue sections, brackets and pipework – was delivered by courier just before 8am. By this time, the engineers had laid down dust sheets over every surface they needed to walk over inside my house before getting straight to work.
Before long, the old boiler had been disconnected and stripped out. As expected, there was a bit of drilling and the usual tool noise, but nothing out of the ordinary, and they kept everything surprisingly tidy as they went.
The flue replacement, which I thought would be the worst bit, ended up being the most impressive part of the install. The guys swapped the entire run, including the part that run through the loft space above the bathroom, without so much as a scuff. I’m still not quite sure how they did it so neatly.
Meanwhile, a scaffolding team had turned up outside, and got what they needed in place to create access to the flue elevated outlet, and erected everything in about 30 minutes. While all that was happening, the engineer was fitting the new boiler in the airing cupboard. It sits on the same wall as the old one but since the 8000+ is a beefy-looking unit, it actually fills the space better. He rerouted and tidied some of the pipework, dropped in the new magnetic filter on the return line, fitted the carbon monoxide alarm and wired up the new thermostat in what felt like no time at all.
The system then got a chemical flush, where they circulate a cleaning solution through all the radiators and pipework to break down sludge and debris before adding fresh water and an inhibitor. I know, it sounds a bit boring, but it’s the sort of thing that can make a big difference to how efficiently your radiators heat up as well as how long your new boiler lasts.
By the time they’d filled, flushed, bled, checked for leaks and run through all the safety tests, it was about 1pm. From arriving to waving them off, the whole thing took just over five hours, which was so much faster than I was expecting. What’s more, they left the house looking the same as it did when they arrived. On top of that, the scaffold team had waited around for the boiler engineer to fit the flue and pulled the scaffolding right back down again, so – unlike my air con install – it was removed within a few hours. A top job!
The whole process was nowhere near the ordeal I’d built up in my head and, despite having to work from home while all this was happening, I hardly knew the engineers were here. Throughout the entire install, it never felt like a building site. They kept the dust under control, hoovered up afterwards and took the packaging and scrap metal away with them. There was no “we’ll come back next week to finish that bit” – it was all done, tested and signed off in one go, right in time for lunch.
Boxt boiler experience: The final result
Now that the Greenstar 8000+ Style has been pumping my house for a good few weeks, the difference compared to my old 25kW model is already quite obvious.
Firstly, it’s generally a nicer thing to live with. The glossy black front and touch-screen display make it look more like a high-end appliance than a purely functional white box. The touch-screen interface feels high end, too, and shows clear text rather than weird cryptic codes, making it easier to understand what it's doing with just a quick glance.
The biggest and most important change, however, is how quickly it heats the house up. From a cold start, the radiators get hot much faster than before. Rooms that used to feel like they took forever to come up to temperature now warm through in what feels like half the time. In real terms, that means I’m less tempted to leave the heating on low all day “just in case” - I can let the place cool a bit and trust that a timed burst will actually do the job.
Hot water performance has stepped up, too. Showers are now a lot more consistent, even when more than one person is using water. Where the old boiler would sulk if two people tried to shower back-to-back or at the same time, the 8000+ just gets on with it. I haven’t had the same pressure dips or random temperature changes I was getting before, and hot water reaches the taps noticeably faster.
When I spoke to BOXT about efficiency differences, they broke it down for me, suggesting that the new boiler should be giving me around 30% more hot water flow compared to my old one – that’s roughly an extra 3.5 litres of hot water per minute, which is exactly what I’m noticing in the shower.
On the heating side, the central heating output is just over 6kW higher, which means my radiators get up to temperature more quickly and the boiler isn’t working flat out all the time to keep the house warm. In theory, that should be better for both comfort and the boiler’s long-term lifespan, but I’m already feeling this in real life, as my radiators are able to warm my room up way faster than before, meaning I don’t have to have the heating on as long.
It’s a bit too early to show what those improvements mean in terms of dosh. The savings will depend on how often I run it, energy prices and how ruthless I am with the thermostat. But purely from how much faster it heats the house and the fact it’s an A-rated, modern condensing boiler that can modulate its output, I feel a lot more confident that I’m not wasting as much gas as I was with an underpowered, less efficient setup. When bills are this unpredictable, having a boiler that can actually keep up without being thrashed constantly feels like a smart move.
Nevertheless, BOXT were also keen to point out that no boiler is magic – even though the 8000+ is A-rated, and if I left the heating blasting all day at 25ºC I’d still burn through gas. The difference is that, used properly with a decent thermostat and sensible timings, the extra output and smarter controls should help the new model run more efficiently and for shorter bursts than a smaller boiler that’s constantly straining to keep up.
So, if you’ve got an ageing or struggling boiler and you’re dreading the hassle of replacing it, I can genuinely say it’s not as painful as you think. In my case, it was five hours, a stack of dust sheets and a few cups of tea.
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