commercial gas water heaters: commercial gas fired hot water heaters; commercial lpg water heater: industrial gas water heaterFlexiheat UK

Commercial Gas Water Heater Range

commercial gas water heaters: commercial gas fired hot water heaters; commercial lpg water heater: industrial gas water heater

Commercial / Industrial Gas Fired Water Heaters – up to 300kW of output – Condensing – ErP A rated Domestic Hot Water – Low NOx for commercial or industrial applications

Commercial gas water heaters – Our commercial and industrial hot water gas fired heating systems, can accommodate a wide range of customer requirements and hot water demands, regardless of your hot water requirements, we’ll have the correct commercial water heater for your needs, whether its on-demand (continuous flow) or storage water heaters for commercial use, we have the solution.

Our commercial water heaters provide a hot water system, with precise temperature control, by combining a condensing gas water heater in conjunction with a stainless steel hot water storage tank to suit your commercial water heater requirements.

By splitting the gas water heaters from the hot water storage tank, gives us the ability to offer unique solutions to meet the needs of every project for its domestic hot water requirements be it commercial or industrial applications.

This allows you to locate the heater element on a wall and use a simple horizontal or vertical flue kit (co-axial or balanced flue), which reduces both install time and flue costs, and then allows you to locate the storage water tank to suit the site requirements. For multiple commercial water heaters, we can supply a floor mounting rig, with all the flow and return pipework etc in a complete commercial water heaters package.

Thus, for smaller applications such as health care facilities, which tend to have a constant hot water systems demand throughout the day, or for larger hot water systems demands such as sports facilities, hotels or showering blocks, which tend to have a higher peak load with short recovery times, we can combine the relevant size storage water tank, with single commercial gas tankless water heater or multiple commercial gas tankless water heaters to suit the duty required for the hot water systems.

Please note that all gas fired commercial water heaters now must be condensing water heaters, as the new part “L” building regulations for the UK that came into force on 15th June 2022, requires that condensing water heaters must be used on existing as well as newly constructed non-domestic buildings i.e., commercial, and industrial domestic hot water heating. Condensing water heaters are more efficient and produce less pollution, with all our gas fired water heaters being condensing water heaters, we welcome this requirement for domestic hot water systems, which will help reduce the impact on global warming.

1. You can place the commercial water heater where you want, for the easiest and most convenient location to suit the site requirements, and the DHW storage tank, again where you require (within reason),this gives maximum flexibility.

2. These commercial water heaters can either be wall mounted (we do pipework kits to make the install quick and easy installation) – or on a full rig – with mounting brackets and pipework kits – just bolt together to the commercial water heater and your away (see pictures below)

commercial hot water heaters: Gas fired storage water heater; industrial water heating; gas fired water heaters commercial a tankless hot water heater with circulating pump and buffer tank

Commercial gas fired water heaters, in a cascade configuration – with bolt together pipework kits and frames- making install quick and easy for your commercial or industrial water heating applications with our ErP compliant gas fired water heaters. Using a tankless hot water heater with circulating pump and buffer tank

3. This often makes flueing the system easy – most people wall hang the units, and go straight out the wall with a horizontal flue kit – or you can go into a common header for a single flue system

4. The problem with the older version direct fired gas water heaters – is that the water tanks are often glass lined, the continual heating up and cooling process – causes them to crack over time, as well as the water attacks the glass lining, meaning they have to have sacrificial or permeant anodes in them – These need servicing / replacing and often get missed – causing the domestic hot water condensing water heaters to fail.

direct fired gas water heaters; industrial water heater; gas fired industrial hot water heater;

Traditional gas fired commercial water heaters – When the tanks fail, they must be completely replaced. Separating the water heater and tank is a good practice for commercial heating of hot water systems

5. Built-in redundancy – should you want to service one of the units – you can still have the other running – if one fails goes you still have 50% of capacity available. A great feature for industrial applications.

6. Our Water heaters are ErP Compliant – “A” rated – Condensing water heaters – maximum efficiency, lower fuel bills.

7. Very low NOx emissions- maximum 50 mg / kWh – kinder to the environment.

8. Modulation of the water heaters – each 50kw unit is 10:1, thus for 2 units the system modulation data would be 20:1

9. Stainless steel 28 mm Ø heat exchanger for full flow, and less chance of getting blocked

We believe in stainless water storage tanks – it’s the best of the best – as they say – No sacrificial anodes are required! for our ERP compliant commercial water heaters. Our domestic hot water storage tank range  options has its own webpage.

Water heaters for commercial premises

Whether you want a gas commercial water heater for your school, surgery, offices, warehouse, restaurant, fast food outlet or any other type of commercial premises, our commercial water heaters, which are condensing gas water heaters are the most economical and energy efficient solution. This range of commercial gas water heater are condensing water heaters and have energy efficient levels of 105%

Should you want more advice on sizing a storage water heaters please click here – how to size a commercial water heater 

Storage water heater or continuous flow hot water systems ?

Gas fired storage water heaters, are a good solution for commercial or industrial hot water systems, as their fast recovery rate of hot water means they are great for a high-volume hot water demand, that can be required for hotels, guest houses, commercial kitchens, shower blocks, health facilities etc.

If your demand is not that high, then you can look at our continuous flow hot water / gas multipoint heaters range, which are condensing tankless water heaters / instantaneous gas water heaters. This product range are very efficient, as they do not use tanks of stored hot water and only heat as much water as you require, rather than having a tankful of water sat around waiting to be used.

The downside of continuous flow water heaters or gas multi point water heaters, are two-fold –

1.If you have a particularly high hot water demand, a multipoint gas water heater may not be able to keep up.

2.If you require a lot of hot water in several points at the same time, the gas demand requirements may be too much to supply your hot water heating system

Flow water heaters

The above term is just another referring name to products or items which are actually flow continuous hot water heating or instantaneous gas fired water products – we supply a range of commercial flow water heaters that are either condensing water heaters or non condensing water heater here – gas multipoint water heaters. All of these units are ERP compliant.

However sometimes a storage water heater is required due to the performance required.

Hot water performance of our commercial water heating gas appliances

Following is the hot water heating performance data , for our commercial condensing gas fired storage water heater range, which are available as either natural (G30) or LPG (G31) propane fuelled


ModelNominal ratingStorage tankPeak hot water flow rate @ 60°C (incoming temperature 10˚C)Peak hot water flow rate @ 45°C (incoming temperature 10˚C)Continuous hot water flow rate (l/hour)
ModelkWlitres1st hr @ 50˚C rise2nd hr @ 50˚C rise1st hr @ 35˚C rise2nd hr @ 35˚C riseat Delta T 50°Cat Delta T 35°C

For condensing water heaters used in cascade – 300 litre storage tanks / vessels cannot be used with more than 3 condensing water heaters.

ModelNominal ratingStorage tankPeak hot water flow rate @ 60°C incoming water temperature 10˚CPeak hot water flow rate @ 45°C incoming water temperature 10˚CContinuous hot water flow rate (l/hour)
ModelkWlitres1st hr @ 50˚C rise2nd hr @ 50˚C rise1st hr @ 35˚C rise2nd hr @ 35˚C riseat Delta T 50°Cat Delta T 35°C
2 x 50/300100300207217722830253017722530
2 x 50/500100500227217723030253017722530
2 x 50/750100750252217723280253017722530
2 x 50/10001001000277217723530253017722530
3x 50/300150300295826584095379526583795
3x 50/500150500315826584295379526583795
3 x 50/750150750340826584545379526583795
3x 50/10001501000365826584795379526583795

For the sake of brevity, we have the data up to 300kW of power input, if you want an industrial gas water heater of this size, just let us know the storage volume and we’ll send you the data tables. This cascade water heater system can support a maximum of 6 water heaters with a single control unit and achieve a modulation of 1:60 for higher yields and reduced energy consumption, and can provide up to 221 litres / minute of domestic hot water with a temperature rise of 25 Degrees C.

commercial water heaters – storage water heaters system diagram

commercial hot water heaters or industrial water heaters which are gas tankless hot water heater or heaters with circulating pump and buffer tank by Flexiheat UK

System schematic showing commercial or industrial water heating systems – gas fired from Flexiheat UK


Internal or external instantaneous water heaters option

We have a 50kW or 100kW ErP compliant tankless water heaters or instantaneous water heaters that come pre-packaged hot water systems or water heaters, that can be used in a cascade installation of up to 300kW – which can be installed internally or externally as the come complete with an ABS cover for outdoor installation.

commercial water heater or condensing water heaters gas fired 50kw or 100kw output packaged for easy installation internal or external - ERP compliant Flexiheat UK

50kw or 100kW Internal or external commercial gas water heater – packaged for easy installation – plug and play as such


Temperature controllers

You can control the water temperature of these commercial water heaters in the onboard control panel or alternatively remote temperature controllers are available that allow precise temperature control by the user of these condensing water heaters.

Quality and Guarantees

Our commercial water heaters are manufactured in accordance with ISO 9001 and ISO 1400i certified management systems and testing techniques. Should you require more information or data on these products- Commercial Gas Water Heaters, or hot water systems then please contact our sales teams for the best water heating solutions for your commercial premises or industrial applications . You can contact our office on 01202 822221 for prices for this range of commercial water heaters products and latest offers.