the complete system and recommend an appropriate Glow-worm boiler installation.

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Is a Glow-worm Boiler Suitable for Your Home?

 

Glow-worm produces combi, system and regular gas boilers for different property types and heating arrangements. The manufacturer’s current domestic range includes Compact, MicraCom, Easicom, Energy and Ultimate products, although model availability can change.

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A Glow-worm gas boiler may be suitable where a homeowner wants:

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• A compact boiler for a flat or smaller house

• A straightforward replacement for an existing combi

• A boiler capable of fitting inside a kitchen cupboard

• A system boiler connected to a hot-water cylinder

• A regular boiler for a traditional open-vented system

• A choice of outputs and guarantee periods

• Smart or programmable heating controls

• A competitively priced gas boiler

• Selected LPG boiler options

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Choosing a suitable model is important, but the quality of the finished installation will also depend on correct sizing, system cleaning, heating controls and commissioning.

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Glow-worm Combi Boilers

 

A Glow-worm combi boiler provides central heating and instantaneous hot water from one appliance.

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Unlike a system or regular boiler, it does not normally require a separate hot-water cylinder or cold-water storage tank. Glow-worm describes combi boilers as a space-saving option that supplies heating and hot water on demand.

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A Glow-worm combi boiler may suit:

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• Flats and apartments

• Smaller and medium-sized houses

• Properties with one main bathroom

• Homes already using a combi boiler

• Properties where storage space is limited

• Projects involving the removal of tanks and cylinders

• Straightforward replacement-boiler installations

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A combi is not automatically the right choice for every home. Larger properties with several bathrooms or substantial simultaneous hot-water demand may perform better with a system boiler and appropriately sized cylinder.

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Check the Water Flow Before Choosing a Combi

 

A more powerful Glow-worm combi boiler will not create better mains-water pressure.

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The appliance can only heat and deliver the volume of water reaching it. If the incoming water main is restricted, a higher-output boiler may still provide disappointing performance at showers, baths and taps.

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The installer should test:

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• Static mains-water pressure

• Dynamic pressure while water is running

• Incoming flow rate in litres per minute

• Diameter of the incoming water main

• Condition of the internal water pipes

• Number of bathrooms and showers

• Likelihood of several outlets being used together

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A combi boiler can work very effectively where a property has one bathroom and a strong mains supply. Where two or more showers may be used simultaneously, stored hot water may provide a more suitable solution.

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The Glow-worm Combi Boiler Range

 

The current Glow-worm combi boiler selection includes products at different price and specification levels.

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The range includes:

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• Glow-worm Compact Combi

• Glow-worm MicraCom

• Glow-worm Easicom₃

• Glow-worm Energy

• Glow-worm Ultimate₃

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The availability, outputs and guarantee packages should be checked against current manufacturer information before the boiler is ordered.

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Glow-worm Compact Combi Boiler

 

The Glow-worm Compact is designed as a lightweight, cupboard-sized combi boiler.

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Current models are available in 24kW and 28kW outputs. They have an ErP A efficiency rating, an LCD display and a five-year guarantee supplied as standard.

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The Glow-worm Compact may be considered for:

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• Flats and smaller houses

• Properties with one main bathroom

• Straightforward combi replacements

• Cupboard installations

• Projects where boiler weight and dimensions matter

• Homeowners looking for an accessible Glow-worm option

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Selected Compact models are also available for LPG installations. Glow-worm currently lists 24kW and 28kW LPG versions with domestic hot-water flow rates of approximately 9.9 and 11.5 litres per minute respectively.

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The correct output should still be confirmed by the installer after assessing the property and available water flow.

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Glow-worm MicraCom Boiler

 

The MicraCom is one of the smallest boilers within the current Glow-worm range and is designed for cupboard installation.

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It has a stainless-steel heat exchanger, a compact illuminated display and dimensions of approximately 626mm by 400mm by 270mm.

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A Glow-worm MicraCom may suit:

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• Smaller homes

• Apartments

• Rental properties

• Cupboard installations

• Direct combi replacements

• Installations with restricted wall space

• Homeowners looking for a straightforward boiler

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The boiler’s small physical size does not remove the need for adequate servicing access, ventilation clearances and a compliant flue arrangement.

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Glow-worm Easicom₃ Combi Boiler

 

The Easicom₃ is a competitively positioned combi boiler available in 24kW and 28kW models.

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The range is designed to provide heating and instantaneous hot water without a cylinder or cold-water tank. It includes an LCD display, an analogue clock and compatibility with Glow-worm’s advanced heating controls.

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The current Easicom₃ product is supplied with a five-year guarantee.

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It may be considered for:

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• Flats and smaller houses

• Properties with modest hot-water demand

• Direct replacement installations

• Homeowners seeking a competitively priced combi

• Properties requiring a relatively compact boiler

• Installations where simple controls are preferred

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A 28kW model may provide a stronger hot-water flow than a 24kW boiler, but the difference will only be realised where the incoming mains supply can support it.

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Glow-worm Energy Combi Boiler

 

The Glow-worm Energy is a compact combi boiler manufactured at the company’s Belper facility.

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It includes an aluminium heat exchanger, a choice of controls and flexible flue options. Its compact dimensions can make it suitable for installation inside certain kitchen cupboards, subject to the necessary clearances and servicing access.

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The Energy range may be relevant where the homeowner wants:

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• A mid-range Glow-worm boiler

• A compact appliance

• A choice of outputs

• Flexible boiler positioning

• A rear or top flue arrangement

• Modern heating controls

• A longer available guarantee

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Glow-worm currently lists a seven-year standard guarantee for the Energy range, with an extended guarantee of up to ten years available on qualifying installations registered by an eligible installer and fitted with a Glow-worm Power System Filter.

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Glow-worm Ultimate₃ Combi Boiler

 

The Ultimate₃ combi provides heating and instantaneous hot water without a separate storage cylinder or water tank.

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It is available in 30kW and 35kW models and is intended to provide stronger domestic hot-water performance for suitable properties.

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The Ultimate₃ may be considered for:

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• Medium-sized family houses

• Properties requiring stronger hot-water flow

• Homes with one main bathroom and an ensuite

• Replacement of an existing higher-output combi

• Households seeking a longer available guarantee

• Properties with a suitable incoming mains supply

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The Ultimate₃ currently has a five-year standard guarantee. A ten-year extended guarantee may be available where the boiler is installed with a qualifying Glow-worm Power Filter and registered through the appropriate installer scheme.

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The higher output should not be treated as a substitute for testing the property’s water pressure and flow rate.

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Glow-worm System Boilers

 

A Glow-worm system boiler supplies central heating and works with a separate hot-water cylinder.

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The cylinder stores heated water so that it is available when required. This arrangement can be more suitable for larger households or properties where several hot-water outlets may be used at the same time.

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Unlike a traditional open-vented system, a sealed system boiler does not normally require feed and expansion tanks in the loft.

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A Glow-worm system boiler may suit:

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• Larger houses

• Properties with two or more bathrooms

• Homes with an existing unvented cylinder

• Households using several showers

• Properties with greater hot-water requirements

• Heating systems divided into several zones

• Homes where stored hot water is preferred

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Glow-worm Energy System Boiler

 

The Energy system boiler is available in 12kW, 15kW, 18kW, 25kW and 30kW outputs.

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It has a compact design, a rear-flue option and a modulating pump intended to respond to heating and hot-water demand. The range can qualify for a guarantee of up to ten years under the appropriate installation and registration conditions.

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The broad range of heating outputs allows the installer to select a boiler that reflects the calculated heat loss rather than installing an unnecessarily large appliance.

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When installing a system boiler, the heating professional should also assess:

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• Cylinder size

• Cylinder recovery time

• Incoming water pressure and flow

• Expansion arrangements

• Motorised valves

• Heating zones

• Cylinder thermostat

• Hot-water programming

• Existing pipe sizes

• Condition of the system water

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The cylinder and boiler must be designed together. A powerful boiler connected to an undersized cylinder will not provide the required stored hot-water capacity.

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Glow-worm Regular Boilers

 

Regular boilers are also known as conventional, open-vented or heat-only boilers.

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They normally work with a separate hot-water cylinder and may also use cold-water storage and feed-and-expansion tanks within the roof space.

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Glow-worm describes regular boilers as particularly relevant to larger households requiring hot water at more than one bathroom. They can also be appropriate where water pressure is low or the property has an older heating system.

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A Glow-worm regular boiler may be suitable where:

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• The existing system is being retained

• The property already has a suitable cylinder

• The pipework is designed around an open-vented system

• Water pressure makes a combi conversion unsuitable

• Several hot-water outlets may be used

• The homeowner wants to minimise alterations

• A like-for-like replacement is more practical

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Glow-worm Energy Regular Boiler

 

The Energy regular boiler is available in 12kW, 15kW, 18kW, 25kW and 30kW outputs.

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It is compact enough for many kitchen-cupboard installations and offers a rear-flue option. The boiler carries a seven-year standard guarantee, with a ten-year extended guarantee available through qualifying installer arrangements.

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The Energy regular boiler may suit:

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• Traditional heating-system replacements

• Properties retaining a hot-water cylinder

• Larger homes

• Projects requiring a compact heat-only boiler

• Installations needing a choice of heating outputs

• Homes where the existing open-vented arrangement remains suitable

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The installer should inspect the existing tanks, cylinder, pumps, valves and controls before recommending a direct replacement.

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Glow-worm Easicom₃ Regular Boiler

 

The Easicom₃ regular boiler is currently available with a 25kW output.

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It includes a compact design, an LCD display, an aluminium heat exchanger and a five-year guarantee.

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This model may be relevant where a homeowner wants a competitively priced replacement while retaining the existing regular-boiler arrangement.

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The 25kW output must still be checked against the actual heat loss and radiator requirement of the property.

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Glow-worm Boiler Prices

 

Glow-worm boiler prices vary according to the model, output, boiler type, controls, flue components and guarantee package.

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A June 2026 market guide lists standalone Glow-worm combi boiler prices from approximately £600 for an entry-level model to around £1,150 for selected Energy boilers. The same guide estimates basic installation costs of approximately £1,000 to £2,200, depending on the work required.

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These are broad market figures rather than fixed APN quotations.

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Glow-worm installation   / Indicative installed cost

Straigh tforward compact combi replacement £1,800–£2,800

Easicom or MicraCom replacement £1,900–£3,000

Energy or Ultimate combi replacement £2,300–£3,600

System-boiler replacement £2,400–£4,000

Regular-boiler replacement £2,300–£3,800

Boiler relocation £3,500–£5,500+

Traditional system converted to combi £3,500–£6,000+

New system boiler and cylinder £4,000–£7,000+

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The final Glow-worm boiler cost will depend on the individual property and scope of work.

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What Affects Glow-worm Boiler Costs?

 

The boiler unit is only one part of the installation price.

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The total cost may be affected by:

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• Boiler range and model

• Boiler output

• Combi, system or regular arrangement

• Standard or extended guarantee

• Existing boiler position

• Proposed boiler position

• Flue length and route

• Roof or high-level access

• Scaffolding

• Gas-pipe size

• Condensate drainage

• Electrical work

• Heating controls

• Magnetic system filter

• System cleaning or flushing

• Chemical inhibitor

• Radiator replacement

• Heating zones

• Tank and cylinder removal

• Installation of a new cylinder

• Floor and wall access

• Making good and decoration

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An advertised boiler price will normally relate to a defined installation package. It may not include relocation, extended flue components, major pipework alterations or repairs to the property.

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The written quotation should clearly identify what has been included and excluded.

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Glow-worm Boiler Replacement

 

A Glow-worm boiler replacement may be relatively straightforward where the new appliance remains in the same position and the existing system type is retained.

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However, the installer should not assume that everything connected to the old boiler remains suitable.

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The pre-installation assessment should include:

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• Existing boiler type

• Proposed replacement model

• Boiler position

• Flue route

• Gas supply

• Condensate drainage

• Heating flow and return pipes

• Radiators and valves

• Hot-water cylinder

• Storage tanks

• Expansion arrangements

• Electrical supply

• Heating controls

• System-water condition

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Replacing an older boiler can improve efficiency, controls, reliability and operating noise. Glow-worm also recommends considering updated controls when replacing an existing appliance.

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A new boiler connected to dirty, restricted or poorly balanced pipework may not deliver the improvement the homeowner expects.

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Converting to a Glow-worm Combi Boiler

 

Many homeowners want to replace a traditional regular boiler and remove the hot-water cylinder and roof tanks.

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This may release storage space and simplify the system, but it involves considerably more work than a direct boiler replacement.

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A Glow-worm combi conversion may require:

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• Removal of the existing boiler

• Disconnection of the cylinder

• Removal or abandonment of roof tanks

• New hot and cold-water connections

• Heating flow-and-return alterations

• Upgraded gas pipework

• New condensate drainage

• A revised flue route

• Electrical alterations

• New heating controls

• System cleaning

• Making good

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The incoming water pressure and flow must be tested before the conversion is approved.

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Where the property has several bathrooms or regularly uses multiple outlets, a Glow-worm system boiler and cylinder may provide a more reliable supply of hot water.

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Choosing the Correct Boiler Output

 

The correct Glow-worm boiler cannot be selected accurately by counting bedrooms alone.

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The installer should consider:

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• Property dimensions

• Construction type

• Insulation levels

• Heat loss through walls, floors and roof

• Window sizes and glazing

• Number and size of radiators

• Underfloor-heating zones

• Number of bathrooms

• Required hot-water flow

• Household usage

• Planned extensions or loft conversions

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Combi boiler outputs are often driven by the instantaneous hot-water requirement rather than the space-heating load.

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A property may require only a modest output for its radiators but need a 30kW or 35kW combi to produce the desired hot-water flow.

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This makes the boiler’s modulation range, controls and commissioning particularly important. An unnecessarily powerful boiler may cycle frequently when the property requires only a small amount of heat.

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Glow-worm Heating Controls

 

Modern heating controls can help the boiler respond more closely to the needs of the household.

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Glow-worm offers smart and traditional control options. Its smart controls use the manufacturer’s eBUS communication system, allowing the control and boiler to exchange information and adjust operation.

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Depending on the boiler and property, the installation could include:

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• Programmable room thermostat

• Wireless thermostat

• Smart-phone control

• MiGo Link

• MiSet control

• Climastat control

• Weather compensation

• Load compensation

• Thermostatic radiator valves

• Separate heating zones

• Hot-water scheduling

• Underfloor-heating controls

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The MiGo Link app can provide remote heating and hot-water control, scheduling and energy-usage monitoring when installed with compatible Glow-worm controls and the required internet gateway.

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The controls should be designed alongside the heating system rather than selected after the boiler has been installed.

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Glow-worm Boiler Guarantees

 

Glow-worm guarantee periods vary by boiler range and installation arrangement.

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The manufacturer currently lists:

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• Energy: seven years standard, up to ten years on qualifying installations

• Ultimate: five years standard, up to ten years on qualifying installations

• Easicom: up to five years

• Compact: five years

• MicraCom: two years standard, with longer cover potentially available through an eligible installer

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Extended guarantees may require the boiler to be installed with a Glow-worm Power System Filter and registered through an eligible installer scheme.

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The boiler guarantee must normally be registered within 30 days of installation. Failure to register within this period can cause the guarantee to revert to 12 months.

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Glow-worm’s terms also require:

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• Installation by a Gas Safe registered engineer

• Correct commissioning

• Completion of the Benchmark logbook

• Annual servicing

• Service records to be retained

• Compliance with the installation instructions

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Homeowners should ask the installer to confirm the exact guarantee applying to the selected boiler and installation package.

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Gas Safe Glow-worm Boiler Installation

 

A Glow-worm gas boiler must be installed by a suitably qualified Gas Safe registered engineer.

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Gas Safe Register confirms that all businesses and engineers carrying out gas work legally must be on the official register. Homeowners should also check the engineer’s ID card to ensure they are qualified for the particular work being undertaken.

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Following the installation, the homeowner should normally receive:

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• Completed Benchmark commissioning documentation

• Building Regulations compliance certificate

• Glow-worm guarantee confirmation

• Boiler instructions

• Heating-control instructions

• Service requirements

• Itemised invoice

• Relevant electrical certification

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In England and Wales, the local authority must be notified within 30 days of a new gas boiler installation. Once notified, a Building Regulations Compliance Certificate can be issued for the property.

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The certificate should be retained because it may be required during a future sale or remortgage.

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What Should a Glow-worm Boiler Quote Include?

 

A proper quotation should identify:

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• Exact Glow-worm range

• Exact boiler model

• Boiler output

• Boiler type

• Proposed location

• Flue arrangement

• Heating controls

• Magnetic system filter

• System cleaning

• Chemical inhibitor

• Gas-pipe alterations

• Condensate drainage

• Electrical work

• Removal of the existing boiler

• Tank or cylinder removal

• Making good

• Guarantee period

• Commissioning

• Certification

• VAT

• Exclusions

• Potential additional costs

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This makes it easier to compare quotations on a like-for-like basis.

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A lower quotation may exclude controls, filter installation, system cleaning, electrical work or repairs to floors and walls. The cheapest initial price may not represent the lowest final cost.

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Find a Glow-worm Boiler Installer Through APN Boilers

 

APN Boilers is being developed as a nationwide resource for boiler installation, boiler replacement and heating-system improvement.

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The network is supported by more than 40 years of experience in residential property, construction and home improvement. We understand that replacing a boiler is not simply a matter of fitting a new appliance to the wall.

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The heating professional may need to assess:

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• Property heat loss

• Radiator output

• Heating flow and return pipes

• Water pressure and flow

• Hot-water demand

• Gas-pipe capacity

• Boiler and flue position

• Cylinder requirements

• Heating zones

• Smart controls

• Planned property alterations

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Through APN Boilers, homeowners can request contact from suitable independent heating professionals covering their area.

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Frequently Asked Questions

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Are Glow-worm boilers good boilers?

Glow-worm offers combi, system and regular boilers across several price and specification levels. The performance of the finished system will also depend on correct selection, installation, controls, cleaning and commissioning.

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How much does a Glow-worm combi boiler cost?

Current market guides place standalone Glow-worm combi boilers at approximately £600 to £1,150. A straightforward installed replacement may commonly cost around £1,800 to £3,600, depending on the selected model and work required.

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Which Glow-worm combi boiler do I need?

The correct model depends on the property’s heat loss, incoming water flow, number of bathrooms, hot-water requirements, installation space and preferred guarantee.

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What is the difference between Glow-worm Compact and Energy?

The Compact is a lightweight, accessible boiler supplied with a five-year guarantee. The Energy is a higher-specification range with more output and installation options and a longer available guarantee.

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Can a Glow-worm combi boiler supply two showers?

A combi may provide substantial hot-water flow where the boiler output and incoming mains supply are sufficient. A system boiler and cylinder may be more suitable where several showers or taps are frequently used together.

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Are Glow-worm system boilers suitable for larger houses?

Glow-worm system boilers can suit larger properties and homes with several bathrooms. The boiler output and hot-water cylinder capacity must both be calculated correctly.

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Can I replace a regular boiler with a Glow-worm combi?

This is often possible, but the incoming water pressure, water flow, gas supply, existing pipework and household demand must be assessed before removing the cylinder and tanks.

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How long is a Glow-worm boiler guarantee?

Current guarantees vary by range and installation package, generally from two to ten years. Registration, an eligible installer, a qualifying system filter and annual servicing may be required for the longer periods.

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Does a Glow-worm boiler require annual servicing?

Yes. Glow-worm requires annual servicing to maintain the guarantee after the first year. The service should be recorded within the Benchmark documentation.

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Who can install a Glow-worm gas boiler?

A Glow-worm gas boiler must be installed and commissioned by a suitably qualified Gas Safe registered engineer.

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Find the Right Glow-worm Boiler for Your Home

 

Choosing the right Glow-worm boiler starts with understanding your property, the existing heating system and the amount of heating and hot water your household needs. APN Boilers can connect you with experienced local heating professionals who can assess the installation, recommend a suitable Glow-worm combi, system or regular boiler and provide a clear quotation for the work. Tell us about your property and what you would like to achieve to take the next step towards a warmer, more efficient home.

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