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Glow-worm Energy 30C Boiler Reviews: Prices and Alternatives

Your boiler is on its way out and you need a replacement. Good chance, you’re tossing up between multiple brands, price points, and models.

Confused? Don’t be.

In our 5-minute review of the Glow-worm Energy 30C combi boiler, we’ll cover everything you need to make the purchase decision, including potential savings, warranties, and premium-brand alternatives.

Glow-worm Energy 30C Review

Are Glow-worm Boilers Any Good?

Most Glow-worm boiler reviews out there will tell you that these appliances are decent. And they are — for a budget brand. They’re a well known manufacturer, so that’s a good start.

But the problem is that most merchants and installers don’t exactly hold them in high regard.

And there’s a good reason for that — Glow-worm is the “budget” arm of Vaillant — the popular competitor of Worcester and other top-shelf boiler brands. And as you may have guessed, when a reputable boiler manufacturer produces a “budget” product, the latter can’t always compete in quality with its more expensive peers. This is why most installers prefer to fit budget combis from Worcester, Viessmann, or Ideal.

That’s not to say that Glow-worm boilers have poor quality. They’re still manufactured at the same plant as their pricier Vaillant cousins, which means they’re subject to the same quality assurance process.

Glow-worm Energy 30C Combi Boiler Prices

If you stick “Glow-Worm Energy 30C” into Google, you’ll see that prices for this combi boiler are sitting at around £850 — and that’s just for the boiler. You’ll pay extra for the flue, flue extensions, filter, thermostat and, of course, installation.

So, what’s the total cost likely to be?

From a local installer, we’d peg the total boiler installation bill at around £1,900 (inc VAT), which is very reasonable for a 30kW combi boiler.

Done deal, then, right?


We just used this on-screen calculator from Heatable to get prices on Worcester and Viessmann, as those are both brands we rate. 

For us, it’s a no brainer, we’d pick this Viessmann Vitodens 050-W 29kW. However, you can get your own boiler quote list from Heatable here.


It’s a near-equivalent of the Glow-worm model in power output, but you’re going to get a longer warranty, a better known brand, and quite frankly, a better overall installation package — all for basically the same price.

But, if you’ve found a Glow-worm supplied and fitted for much cheaper than the price above, keep reading, as it does have some pretty-cool features… if “cool” can be a thing with boilers.

Is the Energy 30C the Right Size Boiler for You?

A 30kW boiler like the Glow-worm Energy 30C is suitable for an average 3-bedroom house, or a small 4-bed, assuming your heat and hot water demand isn’t excessive. (If you’re not planning on running 2 showers at once, the flow rate should suffice).

However, sizing boilers is not a one-size-fits-all process — there are too many other variables to consider. For instance, the age of your home, the quality of insulation, and the type and quantity of glazing dictate how hard your boiler needs to work to maintain a comfortable room temperature.  The Glow-worm Energy 30C combi boiler might fit 1 3-bed perfectly, but be too weak or too powerful for another.

In some situations, a combi boiler may not work at all and you might need another boiler type instead.

A simple, precise way to determine exactly what size boiler you need is to use this quick calculator. After ticking a few boxes covering your property details, hot water, and heating demand, you’ll get the most suitable boilers listed at the top of the screen (no need to supply your personal info or email address).

“Cool” Features

Long(ish) Warranty

The warranty on the Glow-worm Energy 30C is 7 years. This is relatively long, but not as long as the 10 years you’d get with the Viessmann Vitodens alternative we showed you above.

If you’ve read any other boiler reviews on this site, you’ll hear us banging on about warranty plenty — and that’s because warranties are an essential part of the package.

Even if you manage to get yourself the deal of the century, you’ll still likely face a £2,000 bill for any 30kW boiler, including installation. Meanwhile, some boiler manufacturers will happily bank your cash and only give you a minuscule 2-year warranty in exchange.

You want a 5-year boiler warranty as an absolute minimum.

Comparing the Glow-worm Energy 30C directly to the premium brand equivalent, the Viessmann Vitodens 050W 29kW (which comes with a 10-year warranty), you’re losing out on 3 years of warranty.

Cash Savings

If you’ve got a boiler that’s over 10 years old, replacing it with the Glow-worm Energy 30C could save you hundreds per year on energy bills — enough to start recovering the upfront cost. That’s because this boiler model is A-rated, like most new boilers.

Part of this energy efficiency comes from the Grundfos (quality brand) modulating pump; it’s energy consumption is extremely low in comparison to similar pumps.

Here’s a simple chart that will give you an idea of what you could be saving in running costs by replacing your old boiler with an new one, courtesy of the Energy Saving Trust:

new boiler energy savings


Quiet Mark

If your old boiler sounds closer to a steam train than a household appliance, almost ANY replacement boiler is going to be a welcome improvement.

But not all new boilers come with a Quiet Mark certification, whereas the Glow-worm Energy 30C does, partly thanks to its ultra-quiet, automotive-grade aluminium heat exchanger. Big thumbs up…

Compact Design

The Glow-worm Energy 30C is compact, measuring only 700 x 390 x 280. If you want to, you can fit the Glow-worm Energy 30C in a small space like a kitchen cupboard, rather than hanging it on your wall.

The Viessmann Vitodens we’re recommending as a premium-brand alternative is ever-so-slightly larger — 700 x 400 x 300 — but likewise compact enough to fit into a kitchen cupboard.

Glow-worm Energy 30C Boiler Review: Verdict

Unless you can find a local installer to supply and fit the Glow-worm Energy 30C at a hugely discounted rate (including a filter and thermostat), we’d be heading for Heatable and buying the Viessmann Vitodens 50W 29kW equivalent. You’ll get a top-shelf compact boiler with a juicy 10-year warranty for well below the £2,000 national average — an exceptional deal for such a trusted brand. Job done!

What kind of fuel does your boiler use?

Fixed price online with next day installation

Worcester boilers from as little as £1,965.

What’s Next?

Got questions about Glow-worm boilers, or getting your new boiler fitted?

Drop us a line via our contact form and we’ll do our best to help you out.

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