Glow-worm Economy Plus Boiler Guide
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Overview of the Glow-worm Economy Plus Boiler Range
The Glow-worm Economy Plus range was introduced during the 1980s as a compact and efficient option for British households that needed dependable heating without complicated controls. These boilers were built to be simple, practical, and affordable at a time when modern wall-mounted units were becoming the norm.
For many years, the Economy Plus models were popular for their reliability and ease of servicing. They provided steady heat and hot-water support through a traditional open-vented system that used storage tanks and a hot-water cylinder.
Today, however, these boilers are well past their intended lifespan. Efficiency standards and safety expectations have advanced considerably, and most surviving units are now running below optimal performance. In this guide, we cover the main models, key specifications, typical faults, efficiency ratings, and your replacement options through the ECO4 scheme.
Key Specifications
The Glow-worm Economy Plus series was a long-running range of non-condensing, open-flued boilers produced from the mid-1980s into the early 1990s. It was part of a wider “Economy” line-up that included the original Economy, Economy 2, and Economy Plus generations, each offering slightly improved efficiency and simpler service access.
Main models in the Economy and Economy Plus range:
Economy Series
- Economy 40B, 50B, 60B, 70B
Economy Plus Series
- Economy Plus 40B, 50B, 60B, 70B, 80B
Economy 2 Series
- Economy 2 40B, 50B, 60B, 70B, 80B
RS & R Models
- Economy R 40B, 50B
- Economy RS 40B, 50B, 60B
What the designations mean
- “B” indicates a boiler designed for balanced flue operation.
- “R” refers to a standard open-flue model.
- “RS” means “Room Sealed,” which uses a fan-assisted balanced flue system.
- “Plus” versions featured modest efficiency improvements and simplified internal layouts.
- “Economy 2” was the later revision before Glow-worm transitioned to the Swiftflow and Fuelsaver lines.
Technical overview
- Boiler type: Regular (heat-only), non-condensing
- Fuel type: Natural gas
- Flue options: Open, balanced, or room-sealed fan-assisted (depending on model)
- Output range: 12 – 24 kW (40,000 – 80,000 BTU/hr)
- Seasonal efficiency: 70 – 76 % (Band D – E)
- Installation era: Early 1980s to early 1990s
- Average lifespan: 15 – 20 years
The Economy and Economy Plus boilers were compact, reliable, and easy to maintain, which made them a common choice in homes during the 1980s. However, these units are now significantly less efficient than modern A-rated condensing boilers and fall short of current safety and performance standards.
Efficiency and Running Costs
At launch, the Glow-worm Economy Plus was marketed as an energy-conscious upgrade. Yet by modern standards, its non-condensing design wastes a significant portion of heat through the flue.
With efficiencies of around 70 – 75 %, roughly a quarter of all fuel burned is lost. Modern A-rated condensing boilers achieve 90% +, capturing waste heat from exhaust gases to pre-warm the return water.
Typical annual heating-cost comparison
| Property type | Economy Plus boiler | Modern A-rated boiler | Potential saving |
|---|---|---|---|
| Detached home | ≈ £1,000 | ≈ £700 | £300 |
| Semi-detached | ≈ £750 | ≈ £500 | £250 |
| Flat or terrace | ≈ £550 | ≈ £350 | £200 |
Aside from higher gas use, these boilers lack modern controls such as modulation, weather compensation, or digital thermostats. They operate at a fixed output, meaning they burn more fuel than necessary for mild conditions.
Because they rely on an open-flue system drawing air from the room, they also have stricter ventilation requirements and higher safety risk if the flue becomes obstructed.
Replacing an Economy Plus boiler with an A-rated condensing model typically cuts fuel bills by up to 30 % and reduces carbon emissions significantly.
Common Issues and Fixes
The Economy Plus boilers were built with durable components, but after more than three decades of use, failures are increasingly frequent. Some issues are shared across the range, while others are more common to particular models.
Pilot light keeps going out (Economy Plus 40B and 50B)
The smaller 40B and 50B models often suffer from pilot lights that won’t stay lit. Worn thermocouples or blocked pilot jets are the usual cause. These open-flue boilers are also sensitive to draughts, which can extinguish the flame. Cleaning the jet or replacing the thermocouple usually restores function, but persistent failure often points to a weakening gas valve or pilot assembly that is no longer economically repairable.
Ignition or flame failure (Economy Plus 60B and 70B)
The mid-range 60B and 70B models tend to develop ignition problems caused by corrosion on the electrode or a weak spark generator. Inconsistent gas pressure or sticking valves can also lead to short firing cycles where the flame lights and immediately cuts out. Because most ignition components are now discontinued, replacement relies on refurbished parts that may not last.
Overheating (Economy Plus 70B and 80B)
Larger-output models are more prone to overheating as limescale and sludge build inside the heat exchanger. A worn pump or faulty thermostat compounds the issue, causing the boiler to trip repeatedly. Continuous overheating stresses internal joints and can crack the heat exchanger, leading to leaks that are costly to repair.
Kettling noises (All models)
A rumbling or boiling noise signals heavy scale buildup restricting water flow. This is particularly common in hard-water regions. A power-flush or chemical treatment can quieten the system for a short time, but the problem usually returns as deposits reform.
Leaks and corrosion (Economy Plus 70B and 80B)
Corrosion around fittings, pump housings, and pipework is widespread on high-output models. Small leaks gradually reduce system pressure; larger ones risk damaging the control board. Once rust reaches the heat exchanger or casing, the boiler is beyond viable repair.
Poor circulation (Economy Plus 50B and 60B)
Sludge in pipework or a failing circulation pump can leave radiators cold or slow to warm. While flushing may offer temporary relief, ageing pumps often lack the strength to maintain proper flow, leading to uneven heating and higher fuel use.
Thermostat and control faults (Economy Plus 80B)
The mechanical thermostats in the 80B models commonly drift out of calibration. Users may notice short cycling or excessive heat output. Original thermostats are now obsolete, and fitting modern electronic replacements often requires extensive wiring modification.
Flue and ventilation problems (All models)
Every Economy Plus boiler uses an open flue that draws air from the surrounding room. Any flue obstruction or inadequate ventilation can lead to poor combustion or carbon-monoxide risk. Flue corrosion after decades of use is common, and most engineers advise replacement with a sealed, balanced-flue condensing boiler for improved safety.
Obsolete parts (All models)
Gas valves, ignition assemblies, fans, and sensors for the Economy Plus range are no longer produced. Reconditioned parts can sometimes be sourced, but they are costly and carry no long-term guarantee. Each new failure therefore brings rising costs and uncertainty.
After years of operation, these systems often require multiple repairs within short intervals, making full replacement the more reliable and economical option.
Repair vs Replacement
Small repairs can keep an Economy Plus boiler running for a while, but the financial return is limited.
Typical repair costs
- Thermocouple or pilot repair £100 – £150
- Ignition assembly or gas valve £200 – £300
- Pump replacement £200 – £250
- Heat exchanger repair £300 – £400
- System flush and service £100 – £200
Given the boiler’s low efficiency and obsolete components, investing further rarely makes sense. Upgrading to a modern condensing boiler improves energy use, reliability, and safety, while qualifying households can have the work covered under ECO4.
Alternatives and Modern Replacements
For homeowners replacing a Glow-worm Economy Plus, the Ideal Logic Heat range is typically the most compatible solution. It provides similar heat-only functionality, works with existing cylinders, and achieves efficiencies above 90 %.
Benefits of the Ideal Logic range
- A-rated energy performance
- Compact and lightweight design
- Quiet operation
- Compatible with modern controls
- Long manufacturer warranties
Other reliable alternatives include Worcester Bosch and Vaillant regular boilers, though the Ideal Logic range often offers the easiest installation in older systems.
Free Boiler Grant Eligibility
All Glow-worm Economy Plus models are non-condensing, which means they can qualify for replacement under the ECO4 Boiler Grant Scheme if the household meets eligibility criteria.
1. Health Route
If anyone in the household has a condition made worse by the cold, such as high blood pressure, asthma, COPD, heart disease, limited mobility, or a weakened immune system, you may qualify under ECO4’s health-based criteria.
Many councils also offer LA Flex, which extends eligibility to households near the main thresholds.
2. Low-Income Route
Homes with an EPC rating of D to G or total household income below local thresholds may qualify without benefits.
3. Benefits Route
You may qualify if you or someone in your home receives:
- Universal Credit
- Pension Credit
- Child Tax Credit
- Working Tax Credit
- Income Support
- Income-Based Jobseeker’s Allowance (JSA)
- Income-Based Employment and Support Allowance (ESA)
Is It Time to Replace Your Glow-worm Economy Plus Boiler?
The Glow-worm Economy Plus boilers were dependable for their time and provided thousands of homes with reliable heating. Yet after more than three decades, their efficiency, safety, and parts support have fallen behind modern standards.
Upgrading to a new A-rated condensing boiler offers immediate savings on bills, greater comfort, and lower carbon emissions.
If your home still uses a Glow-worm Economy Plus boiler, you may qualify for a free replacement through Free Energy Savings under the ECO4 scheme.
Frequently Asked Questions
The Glow-worm Economy Plus is a regular open-flued gas boiler that works with a hot-water cylinder and separate cold-water tanks, usually located in the loft. It provides heating and hot water for larger homes that use traditional gravity-fed systems rather than modern sealed setups.
The Economy Plus range was produced from the mid-1980s through to the early 1990s, during a period when open-flued boilers were still common in the UK. Many of these boilers were installed in detached and semi-detached properties, and some remain in use today despite their age.
When new, the Economy Plus achieved an efficiency rating of around 70 to 75 percent, which was considered good at the time. Compared with modern condensing boilers that achieve 90 percent or more, the difference in running costs is now significant, often leading to higher gas bills and wasted energy.
Typical faults include pilot light failure, ignition issues, overheating, and leaking seals or pipe joints. Many users also report noisy operation caused by scale buildup inside the heat exchanger. Because of the boiler’s open-flue design, blocked flues and ventilation faults are also fairly common in older installations.
Most original parts for the Glow-worm Economy Plus have been discontinued. Some refurbished or third-party components can still be sourced, but availability is limited and quality can vary. This often makes reliable long-term repairs difficult.
Minor repairs, such as replacing thermocouples or cleaning blocked jets, are still possible. However, major components like gas valves, fans, and circuit boards are no longer produced. Even when repairs succeed, they tend to be short-lived due to the boiler’s age and wear.
If serviced annually by a Gas Safe registered engineer, it can operate safely, though open-flued systems carry more risk than modern sealed boilers. Poor ventilation or damaged flues can lead to incomplete combustion, so it’s important to fit a working carbon monoxide alarm if the boiler is still in use.
Yes. Because the Glow-worm Economy Plus is a non-condensing boiler with low efficiency, it meets the technical eligibility for replacement under the ECO4 boiler grant scheme, provided the household also meets the income or benefits criteria.
The Ideal Logic Heat range is one of the best modern replacements for the Economy Plus. It offers high efficiency, compact design, and compatibility with existing hot-water cylinders, making it a straightforward upgrade for homes converting from older open-flued systems.
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