HRM Wallstar Combi 24/18kW Condensing Oil Boiler

HRM Wallstar Combi 24/18kW Oil Boiler

The HRM Wallstar Combi 24/18kW Condensing Oil Boiler is a compact oil-fired combination boiler designed to provide central heating and domestic hot water from a single wall-mounted appliance.

The Wallstar Combi is particularly suited to smaller properties requiring a space-saving oil heating solution. It provides 18kW of central-heating output and 24kW of domestic hot-water output, with hot water delivered at mains pressure. HRM specifies a hot-water flow rate of 10.5 litres per minute at a 35°C temperature rise.

The boiler uses condensing technology and incorporates an integrated balanced flue, oil filter, non-return valve, condensate trap and expansion vessel as part of its compact installation design.

Key Features

• HRM Wallstar Combi 24/18kW
• Condensing oil-fired combination boiler
• 18kW central-heating output
• 24kW domestic hot-water output
• 10.5L/min hot-water flow at a 35°C temperature rise
• Suitable for smaller properties
• Wall-mounted space-saving design
• Class C2 / 28-second kerosene fuel
• Integrated balanced flue
• Single-pipe oil supply
• Condensate trap included
• Oil filter included
• Non-return valve included
• 10-litre expansion vessel
• Filling loop included
• Manual-reset high-limit thermostat
• Sealed central-heating system
• Compact casing
• Low-NOx burner technology
• A-rated seasonal space-heating efficiency

HRM describes the Wallstar Combi as a complete central-heating and hot-water system mounted on the wall, designed for smaller properties with a heating requirement of up to 18kW.

18kW Heating Output and 24kW Hot Water

The 24/18 designation is important when describing this boiler.

The Wallstar Combi provides:

• 18kW central-heating output
• 24kW domestic hot-water output

Therefore, the product should not be described as an “18kW hot-water boiler” or as having a 24kW central-heating output.

The 24kW domestic hot-water capability allows the boiler to provide higher instantaneous hot-water performance than its central-heating output suggests. HRM specifies 10.5 litres per minute at a 35°C temperature rise.

Condensing Oil Boiler Technology

The HRM Wallstar Combi is a condensing oil boiler designed to recover additional heat from the combustion process.

HRM’s current Ecodesign product fiche lists the Wallstar Combi 24/18kW as a condensing combination space heater with an A energy-efficiency class and seasonal space-heating efficiency of 90.00%. The same fiche gives useful efficiency figures of 90.42% at rated output/high-temperature conditions and 95.33% at 30% load/low-temperature conditions.

This makes the Wallstar Combi suitable for modern oil-heating installations where efficient operation and compact equipment are important.

Compact Wall-Mounted Design

The Wallstar Combi was developed around a space-saving wall-mounted configuration.

HRM’s published dimensions for the internal casing are approximately:

• Height: 900mm
• Width: 475mm
• Depth: 400mm

The external casing is approximately 580mm high and 390mm wide, with a telescopic depth arrangement associated with the wall duct/flue configuration.

This design can help free up floor space compared with conventional floor-standing oil boilers.

Integrated Balanced Flue

The Wallstar Combi is supplied with an integrated balanced flue, making the appliance particularly suited to its compact through-wall installation concept.

HRM specifies a telescopic flue and wall-duct range of approximately 210–340mm, with an additional 100mm extension kit available.

The actual flue configuration, terminal position and clearances must always be installed in accordance with the current manufacturer’s instructions and applicable regulations.

Domestic Hot Water at Mains Pressure

The Wallstar Combi combines heating and hot-water production in one appliance.

HRM specifies:

• Maximum cold-water pressure: 5 bar
• Minimum cold-water pressure: 1.5 bar
• Hot-water output: 24kW
• Hot-water flow: 10.5L/min at 35°C temperature rise
• Hot-water system supplied directly from the appliance

The boiler’s combination configuration makes it particularly useful where a separate hot-water cylinder is not desired.

Sealed Heating System

The Wallstar Combi is designed for a sealed central-heating system.

HRM specifies a maximum operating pressure of 3 bar, an operating temperature range of approximately 60–82°C, and a 10-litre expansion vessel. The system also incorporates a safety relief valve rated at 3 bar.

Kerosene Oil Fuel

The HRM Wallstar Combi uses Class C2, 28-second kerosene as its specified fuel.

The oil connection is a 10mm compression single-pipe connection, while the appliance incorporates an oil filter and non-return valve.

The correct fuel, oil-storage arrangement, supply pipework and commissioning procedure must follow the manufacturer’s instructions and local requirements.

Low-NOx Combustion

The newer Wallstar Combi configuration incorporates low-NOx burner technology. HRM states that the latest Low-NOx Wallstar Combi was introduced to meet applicable European nitrogen-oxide requirements while retaining the compact Wallstar design.

The current HRM Ecodesign fiche gives an NOx emission figure of 60mg/kWh for the Wallstar Combi 24/18kW configuration.

Compact Boiler for Smaller Properties

HRM specifically identifies the Wallstar Combi as suitable for smaller properties with heating requirements of up to 18kW.

The manufacturer’s product information lists the Wallstar Combi for properties with approximately one to three bedrooms and one to two bathrooms, although final boiler sizing should always be determined from an appropriate heat-loss calculation rather than bedroom count alone.

HRM Wallstar Combi 24/18kW Technical Specifications

Specifications are based on HRM’s published technical documentation and Ecodesign data.

Why Choose the HRM Wallstar Combi 24/18?

The HRM Wallstar Combi provides a practical combination of heating and hot-water performance in a compact oil boiler.

Key advantages include:

• 18kW central-heating output
• 24kW domestic hot-water output
• A-rated seasonal heating efficiency
• Condensing technology
• 10.5L/min hot-water flow at 35°C rise
• Compact wall-mounted installation
• Integrated balanced flue
• Low-NOx burner
• Sealed heating-system configuration
• Integrated expansion vessel
• Integrated condensate trap
• Oil filter and non-return valve
• No separate hot-water cylinder required

Suitable Applications

The HRM Wallstar Combi 24/18 can be considered for:

• Smaller homes
• Rural properties without mains gas
• Oil-heated residential properties
• Boiler replacement projects
• Heating upgrades
• Compact utility-room installations
• Properties requiring integrated domestic hot water
• Homes where floor space is limited
• Oil-heating systems using kerosene

EuroFuelSupply supplies heating and energy products for European customers, with quote and wholesale options available for larger requirements.

Frequently Asked Questions

What is the HRM Wallstar Combi 24/18?

The HRM Wallstar Combi 24/18 is a condensing oil-fired combination boiler that provides 18kW of central-heating output and 24kW of domestic hot-water output.

Is the HRM Wallstar Combi a condensing oil boiler?

Yes. HRM identifies the Wallstar Combi 24/18kW as a condensing combination boiler, with an A energy-efficiency class and 90.00% seasonal space-heating efficiency in its Ecodesign data.

What does 24/18kW mean on the HRM Wallstar Combi?

The 24kW figure refers to domestic hot-water output, while 18kW is the central-heating output. This distinction is important when sizing the boiler for a property.

How much hot water does the HRM Wallstar Combi provide?

HRM specifies a hot-water flow rate of 10.5 litres per minute at a 35°C temperature rise, with a domestic hot-water output of 24kW.

What fuel does the HRM Wallstar Combi use?

The Wallstar Combi is designed for Class C2 (28-second) kerosene heating oil.

Does the HRM Wallstar Combi need a hot-water cylinder?

No. It is a combination boiler, so domestic hot water is produced by the appliance rather than being stored in a separate hot-water cylinder.

What is the efficiency rating?

The current HRM Ecodesign fiche gives the Wallstar Combi 24/18kW an A energy-efficiency class and 90.00% seasonal space-heating efficiency.

What size property is the Wallstar Combi suitable for?

HRM states that the Wallstar Combi is suitable for smaller properties with heating requirements of up to 18kW. Actual boiler sizing should be based on a proper heat-loss calculation.

What are the dimensions?

The internal casing is approximately 900mm high × 475mm wide × 400mm deep. The external casing is approximately 580mm high × 390mm wide, with the wall/flue arrangement determining the overall installation depth.

Where can I buy the HRM Wallstar Combi 24/18kW?

EuroFuelSupply lists the HRM Combi Wallstar 24/18kW Condensing Oil Boiler for supply and accepts quote requests for home, business, trade, installer, developer, retailer and wholesale requirements.