100kw Boiler – Commercial gas condensing boilers


A 100kw boiler is suitable for large domestic and commercial applications, such as installation of a wet central heating and hot water systems for commercial buildings such as schools, sports and health centres, offices and hotels and communal heating schemes. This particular 100kW boiler is ErP “A” label / class condensing technology gas boiler with efficiency up to 108.83 % in condensing mode and is available in either natural gas or LPG.

100kw boiler; gb162 v2;basket ; installations;inc vat

100kW Gas Boiler – Natural gas or LPG

They are extremely versatile, usually in a wall hung condensing boiler installation although they can be used in a cascade boiler configuration, and we do a full range of time and space saving mounting frames, complete with flow and return headers, gas pipe pipework, low loss header or plate heat exchanger accessories options for primary heating circuit separation.

100kw gas commercial boilers

The unique feature of our condensing commercial boiler, is that they are constructed with two heat exchangers in one boiler casing, if one fails, you still have 50% of your heating demand functioning. You may also service one of the heating units while the other is still functioning, ensuring that your heating water system is never out of commission. This is a significant feature and advantage of these extremely versatile 100 kw wall hung condensing commercial boilers, and unique on the market as far as we know.


Two heat exchangers within our 100-kw gas fired boilers; Worcester gb162;bosch easycontrol ; search; inc vat

Two heat exchangers within our 100 kw gas fired boilers – Flexiheat UK


Servicing the individual boiler heat exchangers, even when used in a common flue heater configuration, is still possible as each heat exchanger has its own flue non return valve installed as standard.

So, what you have is a duty / standby or a duty assist gas boiler set up, but in a one gas boiler set up.

The other huge benefit this gives our 100kw boilers, is the modulation or turn down ratio is 20:1, there’s not another wall hung commercial condensing boiler on the market that has this range performance or ability to match the outputs or heating load required by the system and ensures minimal energy usage.

Best Heat Exchanger – Stainless Steel

Our wall hung condensing 100kw gas fired boilers have a high quality 28mm diameter stainless steel heat exchanger, unlike some of our competition that use an aluminium construction, which many heating engineers regard as inferior. This large diameter ensures the heating water has low pressure drops, guarantees lower risk of clogging, greater thermal heating efficiency, and greater ease of cleaning.


Condensing boiler 100kW – Product technical details

boiler 100kw; Worcester gb162 ; inc vat; cascade

Gas boiler 100kw R1K100 model technical data from Flexiheat UK


Download the Flexiheat Manual for R1K 100 Gas Fired Internal Boiler

28 mm diameter stainless steel water heat exchanger

Large diameter water ways- that prevent clogging and have low pressure drops.

Low Class 6 NOx emissions

Class leading NOx Class 6 emission outputs for boiler 100kw heat output installations.

Control accessories

This gas boiler is fully compatible with BMS systems that are often used in commercial buildings, when installed with our optional 0-10 volt interface card, that fits neatly into the mounting wall boiler.

For installations in large domestic properties, the boiler is fully compatible for connection to an “OpenTherm” controller, such as Nest, Alexa etc, which enables you to control the operation of the heating and hot water functions of the boiler with voice control, an Pad, computer or a phone app.


These commercial gas boilers have compact dimensions, for their heating power output.

R1K100 boiler dimensions; Worcester gb162; inc vat; England

R1K100 model dimensions from Flexiheat UK


Ensures minimal energy usage

The condensing mode of this particular boiler is at its maximum efficiency when the return water of the heating system is under the dew point of the by-products of the gas be used to power the boiler, which for natural gas is around 55C. The lower the return water temperature of the heating system installation, the more the boilers will condense. The boilers maximum output and efficiency performance is achieved when the return water is at 30C for the heating system resulting in minimal energy usage.

Multi boiler cascade system

You can cascade our 100kw boiler, with the ability of adding the various boiler outputs from our range i.e., 50kW, 60kW,75kW, 100kW or 120kW output boilers. We can cascade up to 960kW of installed output, with various combinations of boiler outputs to suit your commercial applications. We go into this in more depth on this webpage – Commercial gas condensing boilers

100 kw gas fired boiler alongside a multi boiler cascade system; Worcester gb162 ;inc vat; bosch easycontrol;cascade

Ultimately this boiler range is extremely versatile, and makes them suitable for everything from large domestic heating to industrial and commercial applications, either as a standalone boiler or used in a multi boiler cascade system either inline or a back to back configuration. They can also produce domestic hot water when used with an indirect hot water cylinder.

More Information / Prices

Four more information or prices on our 100kw boiler / commercial gas boilers in natural gas or LPG, which benefits from condensing technology and is up to 108.83% efficient, then please don’t hesitate to contact our sales team on 01202 822221 or use our email contact form via the contact us tab.