Industrial gas water heaters
Industrial gas water heaters

150kW or 200kW gas fired industrial water heaters – up to 400kW in cascade from Flexiheat UK
Our industrial gas water heaters are condensing water heaters for maximum energy efficiency and lower hot water heating bills. This industrial gas fired water heater can be used in an industrial instant hot water heater configuration but also can be linked up to a hot water storage tank for water heating applications that require a storage water heater to cover peak or intermittent high demand volumes of hot water.
These gas water heaters are available in either natural gas or LPG/propane-fired hot water systems.
Many applications rely on them for a continuous supply of hot water, thus the term continuous flow water heaters or can be used in stored hot water systems. They possess hot water temperature control capabilities and aim to reduce heat loss for optimal efficiency. Industrial gas fired water heaters are ideal for any office buildings, healthcare facilities, manufacturing processes or settings, and more that require energy efficient industrial water heating solutions.
Industrial gas condensing water heaters
All of our industrial gas fired water heaters are condensing water heaters, with patented advanced burner technologies that ensure reduced energy consumption when producing domestic hot water.
Whether it be to provide hot water for commercial and industrial applications, our ErP-compliant condensing gas water heaters can be used in an instant hot water mode or can be used with a stored hot water tank (storage tank) to ensure that peak water heating demands can be covered.
Either way, we have a full range of water heating solutions for any industrial water heating system requirements you may have.
Industrial tankless gas water heaters
Our industrial tankless water heaters are available in either natural gas fired water heaters or LPG propane gas fired water heaters and are designated the “SFKG” range.
Being condensing water heaters, our industrial instant hot water heaters are a cost effective option when compared to a storage water heater, as they only produce hot water on demand.
Water heater product range and features

SFKG – our Industrial on demand hot water heater range in 150kW or 200kW single units – 400kW in casacde.
This full range of industrial gas condensing water heaters has the following benefits:
- Currently, there are 150 kW or 200 kW industrial condensing water heaters models available, which can cascade up to two units, resulting in a total output of 400 kW. Larger capacity outputs are in the pipeline.
- The casing houses either three (150 kW model) or four (200 kW model) load-balanced 50 kW stainless steel heat exchangers, ensuring even wear and standard integrated redundancy.
- A high-efficiency pre-mix gas burner provides a large modulation range; the 150 kW model has a 30:1 modulation range, and the 200 kW model has a 40:1 modulation range for better load matching of the hot water systems demand.
- Low NOₓ emissions resulting in lower greenhouse gas emissions.
- The heat exchangers are independent of each other, which guarantees the running of the gas water heater even in case of a single exchanger’s failure. The large 28 mm diameter of the stainless steel exchangers ensures maximum heat transfer and high efficiency (up to 112%) with optimal performance with low water pressure drops.
- Electronic ignition.
- Operating temperatures up to 85°C.
- Easy installation with a compact design, which is basically “plug and play”.
- Flueing options for single or cascaded units, i.e the exhaust gas flue system.
150 kW industrial tankless water heater, gas-fired—hot water heating performance flow rate data at various Delta T
Water heating performance is directly related to the operating temperatures required, i.e., the temperature rise shown as “Δt,” which is Delta T.
Water Temperature Rise | Δt 20 | Δt 25 | Δt 30 | Δt 35 | Δt 40 | Δt 50 | Δt 60 | Δt 75 | Flow rate |
SFKG 150 | 110.19 | 88.15 | 73.46 | 62.96 | 55.09 | 44.08 | 36.73 | 29.38 | Litres/minute |
6,611 | 5,289 | 4,408 | 3,778 | 3,306 | 2,645 | 2,204 | 1,763 | Litres/hour |
This 150kW industrial and commercial on-demand gas water heater delivers exceptional instant hot water performance. A standard shower head has a flow rate of 7 litres per minute. In the winter, the temperature of the cold water mains is 10°C for the majority of the UK, while the showering temperature is 40°C, resulting in a temperature rise of 30°C required. This 150 kW industrial instantaneous hot water heater will supply 10 showers with continuous flow hot water if you have the water flow rate and gas supply required.
200 kW industrial tankless water heater, gas-fired—hot water performance flow rate data at various Delta T
Water heating performance is directly related to the operating temperatures required, i.e., the temperature rise shown as “Δt,” which is delta T.
Water Temperature Rise | Δt 20 | Δt 25 | Δt 30 | Δt 35 | Δt 40 | Δt 50 | Δt 60 | Δt 75 | Flow rate |
SFKG 200 | 146.92 | 117.53 | 97.94 | 83.95 | 73.46 | 58.77 | 48.97 | 39.18 | Litres/minute |
8,815 | 7,052 | 5,877 | 5,037 | 4,408 | 3,526 | 2,938 | 2,351 | Litres/hour |
With a delta T of 30°C, this 200 kW industrial tankless gas water heater will supply 14 showers with continuous flow hot water, as long as you have the water flow rate and gas supply required.
Download the SFKG 150 and 200kW Gas fired industrial and commercial water heaters manual
Gas industrial storage water heater option
Certain industrial water heating solutions necessitate the frequent storage of hot water to meet peak demand.Our water heating solution for this is to couple up our industrial water heaters with a domestic hot water storage tank.

Our industrial gas fired tankless water heater range used in conjunction with a DHW storage tank for peak or high domestic hot water demands.
Flueing options
These gas fired water heaters for industrial applications, due to the vertical stack modular design, share a common flue pipe, so there’s only one flue required for each water module. As each heat exchanger with the water heater has a flue non-return valve, each heat exchanger within the water heater’s casing can be isolated and serviced while the rest of the heat exchangers continue to work.
No downtime while servicing
This is important, as there will be no downtime for your industrial hot water systems servicing requirements.
Commercial water heaters or industrial water heaters?
Commercial water heaters generally start at 70 kW and above because the gas safe regulations classify gas pipework greater than 35 mm (1 1/4″) in diameter as commercial gas applications. Ultimately, as such, there’s no hard figure in kW for gas fired commercial water heaters, and when they change into industrial gas fired water heaters. Since the 2022 Building Regulations Part L amendments, water heaters used in commercial and industrial applications must comply with condensing gas water heater regulations—for more information, read more here – Condensing Water Heaters Legislation UK
Ensure proper installation by using a suitably qualified commercial gas safe engineer.
Contact us for your industrial gas water heating requirements
For more details, check stock, lead time, delivery, price, or to order our reliable and high-quality industrial gas water heaters, as we sell our high-performance and competitively priced products directly. Please call our sales service team at 01202 822221 or use our site email contact form.