Widney Slimtronic Plus 12L 24 kW Propane Gas Water Heater

Widney Slimtronic Plus 12L water heater

The Widney Slimtronic Plus 12L is a compact, wall-mounted instantaneous propane gas water heater designed to provide hot water on demand.

Model JSG12ST-S25 uses 37 mbar G31 propane only and features a room-sealed balanced-flue design, fan-assisted combustion, microprocessor control and electronic temperature management.

The manufacturer specifies a 12 L/min nominal water flow, 24 kW nominal energy consumption, 78.3% efficiency and a water-pressure range from 0.20 to 8.0 bar.

Key Features

• Widney Slimtronic Plus 12L
• Model JSG12ST-S25
• 37 mbar G31 propane only
• 12 L/min nominal water flow
• 24 kW nominal energy consumption
• 7 kW minimum energy consumption
• 78.3% stated efficiency
• Wall-mounted installation
• Room-sealed construction
• Balanced-flue system
• Fan-assisted combustion
• Microprocessor gas and air control
• Low-NOx dual-aeration burner
• Electronic temperature control
• LED temperature display
• Child low-temperature interlock
• IPX4 electrical protection
• 220–230 V AC, 50 Hz supply
• 33 W electrical power consumption

Widney Slimtronic Plus 12L Instantaneous Water Heater

The Slimtronic Plus is an instantaneous gas water heater, meaning it heats water as it is required rather than storing a large quantity of hot water in a conventional cylinder.

Widney describes the Slimtronic Plus as using microprocessor control to monitor water flow and temperature and adjust the gas and air supply accordingly.

This makes the product relevant for customers searching for:

• Widney instantaneous water heater
• Widney propane water heater
• Widney LPG water heater
• 12 L/min propane water heater
• 24 kW propane water heater
• room-sealed gas water heater
• balanced-flue gas water heater
• Low-NOx propane water heater

12 L/min Nominal Water Flow

The 12L designation refers to the nominal water-flow specification of the Slimtronic Plus.

Widney’s technical documentation specifies a nominal water flow of 12 litres per minute. The minimum flow varies with the required temperature rise, with the technical specification showing 6 L/min at a 50°C rise and 12 L/min at a 25°C rise.

Actual hot-water flow depends on:

• Incoming water temperature
• Required outlet temperature
• Water pressure
• Temperature rise
• Gas supply
• Appliance operating conditions

For this reason, the product should be described as a 12 L/min nominal-flow water heater, rather than a 12-litre storage heater.

24 kW Propane Gas Heating

The Widney Slimtronic Plus has a 24 kW nominal energy consumption according to the manufacturer’s technical specification. Its stated minimum energy consumption is 7 kW.

The product’s gas consumption is specified as:

• High: 20 kW / approximately 1.72 kg/h propane
• Low: 6.5 kW / approximately 0.49 kg/h propane

These figures describe gas consumption at the stated operating levels and should not be presented as guaranteed household energy consumption.

G31 Propane Only

This model is specifically specified for:

37 mbar – G31 Propane Only

The manufacturer’s gas category is II2H3P, with the burner pressure internally regulated to approximately 19.0 mbar.

This is an important purchasing consideration.

This is not a universal natural-gas model

Do not describe the JSG12ST-S25 as a natural-gas water heater unless the exact appliance supplied has been verified as a different approved configuration.

For this product page, use:

G31 propane water heater

and

propane instantaneous water heater

as the principal fuel terminology.

Room-Sealed Balanced-Flue Design

The Slimtronic Plus uses a room-sealed balanced-flue construction.

This means combustion air and flue gases are handled through the sealed appliance/flue arrangement rather than relying on the room as the combustion-air source.

Widney’s installation instructions state that the JSG12ST-S25 is a room-sealed appliance and does not require purpose-provided combustion-air ventilation for normal operation. Installation must nevertheless comply with the manufacturer’s instructions and applicable local requirements.

Fan-Assisted Combustion

The Slimtronic Plus uses a fan-assisted combustion system.

Its microprocessor controls the gas and air supply while the combustion system is monitored during operation. Widney also specifies a continuously variable fan designed to respond to water draw-off conditions and wind conditions at the flue terminal.

Low-NOx Burner Technology

The Slimtronic Plus uses a dual-aeration burner design.

Widney states that its short-flame combustion technology reduces NOx emissions by 70%, compared with the relevant conventional burner design.

This makes the product relevant to commercial searches for:

• Low-NOx propane water heater
• Low-NOx LPG water heater
• Widney Low-NOx water heater
• low-emission propane water heater
• propane water heater Europe

The 70% figure should be understood as the manufacturer’s stated technology claim rather than a general guarantee of total system emissions.

Temperature Control and Child Safety

The Slimtronic Plus incorporates electronic temperature control with an LED user interface.

The manufacturer specifies a maximum water temperature of approximately 48°C during normal water flow. It also includes a child low-temperature interlock designed to help prevent accidental scalding. Higher water temperatures require the water flow to be stopped before adjustment.

This feature is particularly relevant for applications where safe, controlled hot-water delivery is important.

Water Pressure Requirements

The technical specification gives the following water-pressure range:

• Minimum: 0.20 bar
• Maximum: 8.0 bar

The minimum operating flow varies according to temperature rise. At a 50°C temperature rise, the specification gives approximately 6 L/min, while at a 25°C rise it gives approximately 1.8 L/min minimum flow.

The installer should verify the available water pressure and expected flow before selecting the appliance.

Technical Specifications

The specifications above are based primarily on Widney’s published Slimtronic Plus technical documentation.

Suitable Applications

The Widney Slimtronic Plus can be considered for applications requiring instantaneous propane hot water, subject to proper system sizing and installation.

Potential applications include:

• Residential properties
• Holiday homes
• Park homes
• Mobile homes
• Caravan applications where approved
• Guest accommodation
• Small commercial premises
• Leisure facilities
• Remote properties using propane
• Properties without mains natural gas

The exact application must comply with the appliance’s approved installation conditions and applicable regulations.

Widney Slimtronic Plus for European Customers

The Widney Slimtronic Plus is particularly relevant to customers searching for a compact propane water heater in Europe.

The product’s specified fuel configuration is 37 mbar G31 propane, so customers should verify compatibility with their local propane supply and installation requirements before ordering.

For European installations, check:

• Local LPG/propane supply pressure
• Gas category requirements
• Flue requirements
• Terminal location
• Water pressure
• Electrical requirements
• Appliance certification
• National gas regulations
• Building regulations
• Installer qualification requirements

Regulations can differ between European countries, so the installation must be assessed for the destination country.

Compact Wall-Mounted Design

The Slimtronic Plus is designed as a wall-mounted water heater for applications where compact hot-water equipment is required.

Its room-sealed construction also allows greater flexibility in selecting an appropriate installation location, subject to the required clearances and flue arrangement.

Widney’s installation documentation specifies minimum clearances around the appliance and requires access for servicing and control operation.

Professional Installation

The Widney Slimtronic Plus is a gas appliance and should be installed and commissioned by an appropriately qualified professional.

The installer should verify:

• Propane supply
• Gas pressure
• Gas pipe sizing
• Water pressure
• Water flow
• Flue configuration
• Terminal location
• Electrical supply
• Appliance clearances
• Service access
• Applicable national regulations

The manufacturer’s instructions must be followed for installation, commissioning and servicing.

Widney Slimtronic Plus vs Conventional Storage Water Heater

The Slimtronic Plus is an instantaneous water heater rather than a conventional storage cylinder.

Instead of heating and storing a fixed volume of water, the appliance responds to water demand and heats the incoming supply.

This can be useful where:

• Space is limited
• Hot water is required on demand
• Propane is the available fuel
• A storage cylinder is undesirable
• A wall-mounted solution is preferred

Actual gas consumption depends on water demand, temperature rise, operating conditions and duration of use.

Frequently Asked Questions

Is the Widney Slimtronic Plus 12L a propane water heater?

Yes. Model JSG12ST-S25 is specified for 37 mbar G31 propane only.

Does the Widney Slimtronic Plus have a 12-litre storage tank?

No. The 12L designation relates to its 12 L/min nominal water flow. It is an instantaneous water heater rather than a conventional 12-litre storage tank.

What is the power rating of the Widney Slimtronic Plus?

The manufacturer specifies 24 kW nominal energy consumption and 7 kW minimum energy consumption.

What is the water flow rate?

The nominal water flow is 12 L/min. The actual minimum flow depends on the temperature rise required.

Is the Slimtronic Plus room sealed?

Yes. The JSG12ST-S25 is specified as a room-sealed balanced-flue appliance.

Is the Widney Slimtronic Plus Low-NOx?

Yes. Widney describes the Slimtronic Plus as using a dual-aeration burner and states that its short-flame combustion technology reduces NOx emissions by 70%.

Does it use natural gas?

The JSG12ST-S25 specification is G31 propane only at 37 mbar. Do not substitute natural gas unless the exact appliance configuration is approved for it.

Is professional installation required?

Yes. Gas and flue installation should be carried out by an appropriately qualified professional in accordance with the manufacturer’s instructions and the regulations applicable in the installation country.

Buy Widney Slimtronic Plus 12L Propane Water Heater in Europe

The Widney Slimtronic Plus 12L is a compact room-sealed propane water heater for customers looking for instantaneous hot-water delivery, microprocessor control, Low-NOx burner technology and balanced-flue installation.

For European orders, customers should confirm the G31 propane specification, 37 mbar supply, flue configuration and destination-country installation requirements before purchase.