50kW Boiler – Natural gas or LPG

50 kW Gas Boiler

50kw boiler; 50 kw system boiler; worcester greenstar 8000; worcester bosch; greenstar 8000 life;

Our 50kW boiler which are a gas boiler powered by either natural gas or propane, covers the larger end of the domestic boiler market, and lets you expand into the light commercial boiler requirements that you may have.

They are an ErP “A” rated condensing gas boiler with efficiency up to 108.8 % at 30C return, with key features such as a stainless-steel heat exchanger, fully modulating 10:1 range – which is perfect for heat loading matching ensuring a long and efficient product life cycle and reduced running cost of your central heating system.

They are low NOx emission gas boiler, class 6 – which means they have the least impact on the environment. Available in natural mains gas or LPG. They can be used in a multi boiler cascade system if so required.

50kW system boiler

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50kw System Boiler from Flexiheat UK – Gas Fired

A system boiler, has a separate unvented cylinder for producing and storing domestic hot water. This ensures that a consistent supply of hot water can be delivered to a large number of showers and taps simultaneously. As a result, a its an excellent choice for a property with multiple bathrooms, that require higher domestic hot flow rate.

System boilers do away with the requirement for a water tank in the loft since they get their water straight from the mains (which is required with a regular boiler). They then heat the water to provide warm water for the cylinder as well as central heating.

You have to install a heating expansion vessel on the installation (by others) which is usual at this output boiler.

System pressure for the hot water is mains water pressure and the stored water gives an excellent flow rate, which overcomes some of the problems with combi boilers.

Because combi boiler they are only really meant to sustain one hot water outlet at a time, they are not well suited to households with a high demand for domestic hot water. Heating performance may well be reduced in high-usage households because combi boilers routinely switch the burner from the heating system to hot water when there is a hot water demand.

This boiler can be matched up to various sized cylinders to suit the home requirements for heating and hot water outputs, with effortless comfort.

However, should your flow rate requirement be under 20 Litres / minute, then a combi boiler could be the best option, as a combi boiler produces hot water on demand – look at our wall hung 50kW combi boiler webpage for more information. A combi boiler does both heating and DHW, and is a ErP A rated for reduced running cost.

Key features of our 50 kw gas boiler

Natural Gas or LPG fired

Our efficient boilers are available in natural gas or LPG (Propane) powered units and are a great central heating boiler replacement.


The gas boiler heat output range is 49.19 kW down to 4.83 kW on an 80C/60C heating circuit, or 53.40 kW down to 5.15 kW heat output on a 50C/30C heating circuit

50kw gas fired system boiler- R1K50 model - technical data chart - Flexiheat UK; 50kw system boiler; worcester greenstar 8000; worcester bosch; greenstar 8000 life;

50kw gas fired system boiler- R1K50 model – technical data chart – Flexiheat UK

Modulation up to 1:10

For greater efficiency and reduced consumption both in heating and in domestic hot water production, when used with hot water cylinders

Low Class 6 NOx emissions-

NOx is a catch-all term for nitrogen oxides, which primarily include nitric oxide (NO) and nitrogen dioxide gas (NO2), our boilers have the lowest class emissions

System Pressure

These wall hung gas boilers can operate on a heating circuit with a minimum pressure of 0.3 to 3 Bar maximum

Quality components

All boiler sub components are leading brand products and are selected through careful research for a guarantee of quality and reliability over time

An improved display screen

With push control buttons – for easy control of this 50kW gas fired boiler. With fault codes , for fault finding if there’s ever a issue.

Unrivalled quality / price ratio

The best boiler performance at affordable prices

A wall hung boiler, with modern upgraded controls, that make it one of the most efficient and also one of the quietest boilers manufactured on the UK and Irish markets – at only 52 Decibels noise level – which makes a difference with quieter operation.

Heating output –

The gas boiler power will modulate the heat to the demand of the customers heating system installation, as the boilers output power range will go from from 50kw down to 5kW

Because the heat requirements of a gas boiler do not remain constant throughout the year owing to changing seasons, it may only be running at 20% of its capacity when it is warmer or at 80% when it is colder, our fully modulating 50kw gas boiler adapts to the heating system requirements, providing higher efficiency and reducing cost through wasted energy consumption.

Heating and Hot Water

Heating and hot water is provided by the boiler, via an indirect cylinder / calorifier – The heating side will heat your radiators or underfloor, whilst providing heat for the coil for the indirect cylinder


We do a range of controls that make your life easier, when it comes to controlling your boiler, from a basic room thermostat / programmer, with push control buttons all the way up to enhanced wireless internet controllers, such as Nest, Hive or bosch easycontrol thermostats, with features that provide you with the ability to regulate and control your heating from any extended location away from your home


We do a full range of flue options, such as horizontal or vertical kits, or additional flue lengths in 0.5 or 1 metre extensions that ensure installation in the home easy – they are 80 mm / 125 mm outside diameter concentric – thus room sealed

Space required for installation

This 50kw heating boiler range is compact and modern, through award winning innovation in design and operation, it is also one of the quietest boilers to date on the UK and Irish markets -allowing you to locate the unit in any room and keep you cosy in the cold winter months.

50kw Gas boiler - R1K50 Dimensions Flexiheat UK; worcester bosch; worcester greenstar 8000; greenstar 8000 life;

50kw Gas boiler – R1K50 Dimensions Flexiheat UK


Pipework connection detail

Pipework connections for the R1K50 gas boiler; worcester greenstar 8000; worcester bosch; greenstar 8000 life; registered in england; quote;

Pipework connections for the R1K50 ( at the bottom of the unit )


For easier installation, service, and maintenance, all installer touchpoints have been optimized, with a system pressure gauge located in an easy to read location on the front panel of these gas boilers which gives good peace of mind.

Download the Flexiheat Manual for R1K 50 Gas Fired Boiler

Frequently asked questions

How many radiators can a 50kw boiler run?

The number of radiators a 50kW output boiler can run, will depend on the property. The average sized radiator in a new build home is 1.5kW output, thus newer properties the boiler can run 30 rads to be safe. With older less insulated properties, you’re looking at around 18 to 20 rads, click here for more details

Is a higher kW boiler better?

Boiler are sized to overcome the heat loss from the property ( normally at -5C outside, to give an internal temperature of 20C) in the previous years , you could oversize a boiler, which was not good for efficiency and your fuel bill, but these days the quality end of the market ensures that the boilers are modulating, which means they will operate down to some very low outputs – our 50kW gas boiler will operate down to 4.83kW flow rate, which ensures better heat load matching of the system, with high efficiency and lower running costs , click here for more details.

Gas safe registered engineer

As always, we insist that any gas boilers are installed by a gas safe engineer, not only for the interest of safety, but also for the fact that it’s a legal requirement for the gas installation to be done by a suitable qualified person, so you can sit comfortably, knowing you heating and hot water system is safe. See here for the gas safe website.

Flexiheat UK

Should you require any more information on our 50kw boiler, then our customer services sales team is available (Trading hours -Mon Tue Wed Thu Fri – 8am to 5 pm) to give you a quote and check stock details. Please follow us on social media to keep up on our news, reviews etc.