Our guide to Glow-worm boilers
Considering a Glow-worm boiler? Learn more about the proudly British brand and how we can get one installed in your home.
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If you’d like to talk to a Glow-worm boiler expert face-to-face, or want to change your boiler type or location, book a 90-minute appointment with us.
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If you plan on getting a new Glow-worm installed in the same place, then you can quickly and easily get an estimated quote online.
How Glow-worm boilers began
Celebrating its 90th birthday in 2024, Glow-worm was originally founded as The Glow-worm Boiler and Fireplace Company Ltd and is one of the best-known boiler brands in the UK. It first began manufacturing boilers in 1934 at the Derwent Foundry in Derbyshire – and it’s still based there in the lively town of Belper to this day.
Proudly British, Glow-worm has received Made In Britain accreditation for its Energy, Ultimate and Easicom boiler ranges. In 2001, it was acquired by the Vaillant Group and so became Europe’s largest domestic heating company, employing over 12,000 people in the UK, Europe and China. Today, it continues to produce a range of domestic gas boilers, including combi, system and heat only boilers.
Why choose a Glow-worm boiler?
With so many boilers on the market to choose from, it can be difficult to narrow down the options and find the best boiler for your home. Luckily, our heating and boiler experts here at British Gas can help you do just that. We only stock the best boiler brands, so you know you’re in safe hands when you choose British Gas for your new boiler installation.
All the boilers we offer are carefully selected for efficiency and performance – and the Glow-worm boilers are no exception. Like all the boilers we stock, our Glow-worm boilers are A-rated for efficiency, so you can rely on them to heat your home without wasting energy.
Exploring the range of Glow-worm boilers
Finding the right boiler for your home can seem like a minefield. After all, there are so many different factors to consider. But British Gas can help take the stress and guesswork out of finding the right Glow-worm boiler for you. When you buy a new boiler from British Gas, we’ll ask you a few questions about your home and heating so that we can work out the best boiler for you.
There are three main types of boiler and we’ll help you find which would be the best for your home.
Glow-worm combi boilers
The most popular type of boiler in the UK, combination (or combi for short) boilers provide heating and hot water from a single unit. There’s no need for a separate hot water tank. This makes them a great option for homes that are short on space, or don’t have a loft.
A Glow-worm combi boiler will give you hot water on demand – just turn on the tap. There’s no need to wait for a tank to heat it up. As everything is in one unit, a Glow-worm combi boiler can be quicker to install and cheaper to maintain than other types of Glow-worm boilers. The main disadvantage of a combi boiler is that it can only provide hot water to one place at a time – so that means if one person is showering, someone else can’t do the washing up at the same time.
Glow-worm regular boilers
Also known as ‘conventional’, ‘open vent’ or ‘heat only’ boilers, regular boilers comprise a boiler, storage cylinder and a water tank. Glow-worm regular boilers are specifically designed to be durable and easy to use.
The main advantage of a Glow-worm regular boiler is that it can supply hot water to multiple taps at the same time, even in areas with low water pressure. A Glow-worm regular boiler would be perfect for you if you have a busy household with more than one bathroom – so different people can shower at the same time.
Glow-worm system boilers
Like regular boilers, system boilers also have a separate hot water tank and can provide hot water to different taps at once. However, unlike regular boilers, they don’t need a cold water tank. All the pumps and valves that are separate in a regular boiler are built-in with a system boiler, so it takes up less space. They’re also known as ‘closed vent’ or ‘system sealed’ boilers.
A Glow-worm system boiler is a great space-saving solution for households where different people need hot water at the same time.
Glow-worm boiler reviews
What customers think on 
It heats my home and hot water on demand and does a fantastic job. Smart looking too. It does what all the expensive brands do, but at half the price.
Very efficient and the boiler looks nice clean and slimline, the controls are very easy to use.
The new efficient Glow-worm boiler is excellent, and I’ve seen a noticeable reduction in my utility bills. I would most definitely recommend it.
This is a great replacement for our aged boiler; much quieter, more efficient and smaller in overall size.
Replaced my old boiler after 18 years with a new Glow-Worm c30 and I’m very pleased with how quiet and efficiently it runs.
Frequently Asked Questions
How to check the pressure on a Glow-worm boiler
It’s a good idea to check the pressure on your Glow-worm boiler once a month. Typically, the pressure of your Glow-worm boiler should be between 1 and 1.5 bars. If it falls below this, you will probably need to re-pressurise your Glow-worm boiler.
How to check the pressure on your Glow-worm boiler depends on the model of Glow-worm boiler you have. Generally, most models of Glow-worm boiler display the pressure on the front of the Glow-worm boiler interface. The pressure gauge on your Glow-worm boiler will be either physical or digital, and the dial or bar will tell you the pressure level of your Glow-worm boiler system.
How to reduce pressure on a Glow-worm boiler
High water pressure in your Glow-worm boiler can be caused by high water levels, or the failure of internal boiler components. If your Glow-worm boiler pressure is over 1.5 bar, then you need to reduce pressure in the system by bleeding your radiators. Luckily, this is something that is relatively easy to do yourself and you won’t need to call in a professional.
Follow these step-by-step instructions to reduce boiler pressure on a Glow-worm boiler:
1. Switch off your boiler and wait for it to cool down
2. Use a radiator key or screwdriver to turn your radiator valve anti-clockwise
3. As soon as the water is out, you’ll hear a hissing sound – this is the air escaping
4. When the sound stops, water will start coming out – so have a container handy to catch it
5. Once the water is out, re-tighten the valve and move on to the next radiator
Once you’ve finished, the pressure on your Glow-worm boiler should be at around 1.3 bar.
What do if there is no hot water while using a Glow-worm boiler
There are a few things you can do that could solve the issue without having to call in an expert.
1. Check the fuse box
If other appliances are working, make sure a switch hasn’t tripped and power is still going to the boiler.
2. Check the pilot light
Check the manual and follow the instructions to relight it if it’s gone out. If it keeps happening, get it checked by an engineer.
3. Check the water pressure
The ideal Glow-worm boiler water pressure is 1 to 1.5 bar. If it’s dropped, adjust it carefully using the filling loop.
4. Check the thermostat temperature.
Your boiler might not come on at all if the thermostat is set below 21℃, so you might need to increase it.
What is the price of a Glow-worm boiler
Because Glow-worm produce a wide range of boilers, the cost will vary. The price of a Glow-worm boiler depends on a few factors, including the type of Glow-worm boiler you go for, the model type and the size and energy output of the Glow-worm boiler.
When you buy a new Glow-worm boiler from British Gas, your price includes:
- Expert installation
- Up to 12 years’ warranty
- Impartial advice to find the right boiler for you
What are the Glow-worm boiler fault codes?
The fault codes of a Glow-worm boiler depend on the range it comes from, but common examples include:
Energy Glow-worm boiler range
F10 Flow temperature sensor defective
F22 Low water pressure
F88 Gas valve fault
Betacom Glow-worm boiler range
F00 Flow heating temperature sensor fault
F20 Overheating fault
F67 Fault in main board
hxi Glow-worm boiler range
F4 Ignition fault
F16 Flame detection fault
F26 Poor circulation
Where to find the Glow-worm boiler manual
You may have a hard copy of your Glow-worm boiler manual filed away carefully or stuffed in a drawer somewhere. But don’t worry if you can’t find it – you can download the manual from the Glow-worm website.
What to do if the Glow-worm boiler has a flashing symbol
If you have a Glow-worm boiler from the Betacom range and see a red flashing light, it could be an indication that it’s overheating. The best thing to do is double check the manual to find out why your Glow-worm boiler is flashing – you can download it from the Glow-worm website.
How to reset a Glow-worm boiler
Most Glow-worm boilers have a reset button on the user controls. Just press this to reset your Glow-worm boiler. If you can’t find it, check the manual of your Glow-worm boiler.
If resetting your Glow-worm boiler doesn’t resolve your issue, then British Gas can help – whether you have boiler cover with us or not. Starting at just £21 a month, HomeCare gives you unlimited boiler call-outs and repairs, including all parts and labour. But even if you don’t have HomeCare, you can book an expert British Gas engineer to fix your boiler.