200 Litre direct unvented cylinder – Electric water heater

Looking for a 200 litre direct unvented cylinder or 210 litre direct unvented cylinder in duplex stainless steel ? then we have you covered as we supply a 215 litre direct unvented cylinder which covers these direct models hot water capacity.

Manufactured in the UK, with quality manufacturing processes,our 200 litre direct unvented cylinder full conforms to the “G3” unvented cylinder building regulations , having WRAS, NSF WRC, CE and KIWA independent approvals.

This 200L direct unvented cylinder is a twin immersion cylinder, with 2 x 3kW immersion heaters fitted as standard to this direct unvented hot water cylinder.

Our 200 Litre unvented direct cylinder offers mains pressure hot water powered by electricity directly, rather than using a gas boiler or oil boiler to power the unit like in an indirect unvented cylinder type.

These 200 litre direct unvented cylinders come with a 25 year warranty for the corrosion-resistant duplex stainless cylinder when used in domestic hot water heating applications.

Our 200L unvented direct cylinder will provide a plentiful supply of hot water for your bathroom or showers at mains water pressure.No additional pump is normally required for the hot water system with a direct unvented cylinder.

This competitively priced cylinder is made with quality manufacturing processes in the UK and has high flow rates for cold water mains pressure water heating.

These 215 Litre direct unvented cylinders (which cover 200 or 210 Litres models) are generally suitable for a 3 Bedroom property with 2 Baths/Showers.

No external expansion vessel is required

This 200 litre direct unvented cylinder has a patented internal hot water expansion system which eliminates the need for an external expansion vessel by using a venturi valve to maintain an air pocket within the direct unvented stainless steel cylinder.

This unvented system ensures a long product life and performance for the direct unvented cylinder because it has no moving parts, which reduces installation, running and lifetime costs for this 200 litre direct cylinder made with quality manufacturing standards and processes.

Our internal air gap and venturi valve system used on our direct unvented hot water cylinders- no external expansion vessel is required and little to no maintenance is required for this competitively priced cylinder / unvented hot water system.

Stainless steel direct unvented cylinder – 200 Litre

Our 200 litres direct unvented cylinder is manufactured in stainless steel, duplex stainless steel to be exact. This duplex stainless steel is known for its excellent strength, exceptional resistance to stress corrosion, cracking and pitting, making it suitable for demanding water heating conditions.

Stainless steel tanks or cylinders are also suitable for installing in soft water areas as well as hard water areas. Glass lined mild steel tanks should not be used in naturally soft water areas, as this type of unvented cylinder can experience significant and rapid corrosion to the product.

Technicnal specification – 200 litre direct hot water cylinder (210 &215 Litres as well)

Our 200 litre direct unvented hot water cylinder has the following dimensions (yes our unit is 215 Litres of storage – so also covers the 210 litre direct unvented cylinder requirements)

Unvented direct hot water cylinders – Dimensions drawing for 80 Litre to 500 Litre models

Our 200 litre hot water cylinder dimensions are as follows 

200 Litre direct unvented cylinder – it’s actual 215 Litres of volume – so covers the 210 direct unvented cylinder requirement as well.

Hot water heat-up time and recovery rates for our direct unvented cylinder, 215 litres in capacity

As standard, our 215 litre direct-pressurised hot water cylinders in high-grade stainless steel are fitted with 2 x 3kW immersion heaters with proven technology and quality.Following are the hot water heat up times.

Water heating and recovery times in minutes for our 200 litre unvented direct cylinder with the standard 2 x 3kW immersion heaters.

We also do the unit with 3 immersion heaters (3 x 3kW) or can upgrade the power output of these immersions to 6kW each – giving a total kW output possible of 18kW for this size hot water cylinder. This affects the above times accordingly.

The full brochure and installation manuals are here – 

Download the Hot water cylinders direct and indirect unvented brochure from Flexiheat UK

Download the installation & technical manual for our direct and indirect hot water cylinders

Should you require a different volume direct unvented hot water heater, we have a full range from 80 Litres to 500 litres in capacity, which are detailed on this webpage – 80 to 500 Litre direct unvented cylinders.

200 Litre direct cylinder standard components

Our 200 litre direct unvented cylinder models come complete with the following supplied accessories to suit the product –

2 x 3kW Incoloy immersion heaters including control and cut out thermostats as standard with our dual immersion cylinder.

Option of 3 x 3kW immersion heaters – making this 215L direct cylinder a triple immersion heater cylinder – we can actual fit 3 x 6kW immersion heaters to this unit if so required.

22mm Cold water inlet pressure reducing valve /expansion relief in a combination valve for high flow rates

22mm Hot water outlet, again for high flow rates

Our 200L unvented direct cylinders are fitted with a secondary DHW return connection as standard.

Dual thermostat (control thermostat and energy cut out thermostat)

Tundish

Pressure and temperature relief valve mounted to the direct unvented cylinder.

200 litre direct unvented cylinder installation

All direct unvented cylinders must be fitted by a plumber or heating engineer with “G3” unvented qualifications; this certification ensures the necessary knowledge and skills to install and maintain unvented hot water storage systems. In the UK, building control will not issue a building regs certificate unless a qualified person has fitted the unit.

To locate a G3 qualified heating engineer close to you, please consider using this website – gas safe register

Contact Flexiheat UK

For further information or more details, check stock availability, lead time, delivery, prices or to purchase our 200 litre direct unvented cylinder, as we sell direct our competitively priced cylinder, which is made in the United Kingdom from duplex stainless steel with quality manufacturing methods and a manufacturer 25 year warranty (for domestic use). Please contact our sales team on 01202 822221 or use our site email contact form.

210 Litre indirect unvented cylinder

Our 210 litre indirect unvented cylinder is the best and most competitively priced cylinder on the UK market, manufactured in stainless steel with proven technology and quality manufacturing for maximum life with the capacity to supply mains pressure hot water for your bathroom, shower, wet rooms, and kitchen tap hot water demands in domestic properties via a domestic hot water sealed system.

Conventional boiler powered

This indirect unvented cylinder is “indirect,” meaning that the cylinder has a coil within the inner cylinder, which needs to be connected and fed by a conventional boiler or traditional boiler, be it an electric boiler, gas or oil boilers.

Being an unvented water storage cylinder, you cannot use solid fuel boilers as the heat source. You must use a vented cylinder for solid fuel boilers, that has a vent pipe to account for the DHW expansion.

Unvented hot water storage tank

Our 210 Litre indirect unvented hot water cylinder does not require an external expansion vessel, as it uses a patented self-sustaining internal air gap within the cylinder to account for the hot water expansion pressure that requires minimum to no maintenance.

Unvented domestic hot water self-sustaining expansion system, so no external expansion vessel is required for our unvented hot water cylinders – Flexiheat UK

What is an unvented indirect cylinder?

A 210 ltr unvented indirect cylinder receives its supply directly from the mains water supply directly, allowing it to produce hot water at a significantly higher pressure than a traditional vented cylinder due to its pressurisation.

An indirect unvented cylinder is a type of hot water cylinder that uses a primary coil to heat water indirectly, providing a safe and efficient hot water supply.

Indirect unvented cylinders are designed to work with a boiler as a heat source, providing a reliable and efficient domestic hot water supply.

What hot water demand is a 210L indirect hot water cylinder suitable for?

The overall amount of hot water used is also greatly influenced by individual behaviours. The amount of hot water used by two houses of the same size might range greatly, with one household needing twice as much as the other.

Understanding peak demands and making sure you have the ideal ratio of cylinder capacity to reheat times are the most important factors.

As a general guideline, use the following average consumption values for hot water requirements per person per day:

• Low Consumption: 20–30 litres

• Average consumption: 30–50 litres.

• High consumption: 50–70 litres

source – hotwater.org.uk

Generally, a 3-bedroom property with multiple bathrooms i.e. 1 or 2 baths or showers should utilise a 210L unvented indirect cylinder.

Although if the household is a high-water user, then you should look at the next volume size up cylinder, our 250 Litre unvented indirect cylinder, which is detailed on this webpage – 250 Litre indirect unvented cylinder.

The product offers key specifications, features, and benefits

• Made from highly corrosion-resistant duplex stainless steel, these 210L unvented indirect models ensure a long product life and minimal maintenance.
• Note: no sacrificial anode is required for a stainless-steel unvented cylinder.
• We manufacture and certify our units in accordance with the BBA, CE, KIWA, ISO, NSF WRC, and WRAS independent approvals.
• The full benefit of quality manufacturing and proven technologies at a competitive price.
• We use a stainless-steel indirect heating coil (a heat exchanger) to speed up heat transfer, minimise heat loss, and enable high flow rates. This corrugated coil heat exchanger provides faster reheat times compared to standard plain tube coils.
• We use 60 mm thermal insulation to reduce heat loss – we use reduced heat loss manufactured factory-injected polyurethane foam insulation bonded onto our highly corrosion-resistant duplex stainless steel tank on our 210-litre cylinder to minimise heat loss and running costs. This high-grade insulation is HCFC/CFC free (ODP=0, GWP=1).
• Minimal heat loss: Because these units have an ErP rating, they lose less heat, which is better for the environment.
• It comes standard with a 3 kW immersion heater. This immersion heater is made from Incoloy for long durability that can be used for additional off-peak immersion heating, top-up or emergency water heating should the gas or oil conventional boiler fail.
• The factory set pressure relief valve ensures a safe and efficient operation of these stainless steel indirect water heaters.
• Features a secondary return for a DHW recirculation system if required
• It offers high flow rates for showers and baths in both residential and commercial settings at a maximum inlet pressure of 3.5 bar, eliminating the requirement for a booster pump.

Our 210 litre indirect unvented hot water cylinders are manufactured from duplex stainless steel and thus don’t require a sacrificial anode, which results in less maintenance time and costs for our 210 litre indirect unvented cylinders.

Our indirect unvented cylinder range allows for installation in smaller spaces because it doesn’t require an external expansion vessel. On the left is our indirect unvented cylinder with no expansion vessel installed, and on the right is an indirect cylinder with an external expansion vessel system, which requires a lot more space for the associated pipe work and connections.

On the left – our patented internal air gap system indirect hot water cylinder – on the right – competitor units require an external expansion vessel which requires more space and installation time and copper tube and fittings.

Hot water cylinder detail for our 210 Litre unvented indirect cylinder

First we have the dimensions of our indirect unvented cylinder, 210 litres in capacity.

Our indirect hot water heater dimensions diagram

Dimension data in “mm” for the above specification diagram

All dimesions in mm

The below heat exchanger coil output (kW) is based on a flow temperature of 85°C. If you require higher outputs, then please see our indirect high recovery cylinder range.

Download the Indirect and direct hot water cylinders in stainless steel brochure from Flexiheat UK

Download the  Installation and maintenance manual for Flexiheat UK indirect and direct hot water cylinders

Standard supplied indirect hot water cylinder unvented components

• Temperature/Pressure Safety Relief Valve: set at 90°C and 7 bar pressure (factory fitted to the indirect unvented cylinder)
• The combination (control) valve consists of a line strainer, a non-return (check) valve, a pressure reducing valve, and an expansion relief valve. Supplied loose to be fitted to the incoming cold water mains pipework to reduce the maximum inlet pressure.
• 3 kW Incoloy (a better material than stainless steel) immersion heater, which is single-phase 240-volt powered, incorporating a control thermostat and resettable safety cut-out with WRAS independent approvals. For backup hot water heating or a cheap tariff electric power.
• We have the option to upgrade the immersion heater to a 6kW version on this indirect unvented cylinder, which can be powered by either 1 phase or a 3-phase electric power supply.
• The energy cutout thermostat is set to operate at 82°C (+/-5°C).
• A motorised valve is designed to cut the heat source plumbing to the cylinders in the event of a high-temperature cutout activation.

Warranty of our indirect unvented cylinder

Because this 210L indirect unvented hot water cylinder is manufactured in duplex high-quality stainless steel, which is highly corrosion resistant.

The hot water cylinder comes with a 25-year guarantee when used in a domestic water heating application (standard household use). Warranties vary if used in a commercial water heating application, then the warranty is reduced to 5 years.

G3 unvented indirect cylinder installation regulations

For England and Wales, our indirect unvented cylinder range is covered by Section G3 of the Building Regulations. For Scotland, it is covered by Technical Standard P3, and for Northern Ireland, it is covered by Building Regulation P5. Compliance can be achieved through a Competent Person Self-Certification Scheme, where a heating engineer with the Unvented G3 Certificate possesses the necessary knowledge and skills to install and maintain unvented hot water storage systems, or by notifying the local authority building control department.

Do not try to install or service an unvented cylinder unless you have the necessary certificate or qualifications. An unvented hot water cylinder can explode if not correctly fitted with all of the safety systems that they require.

Installation and maintenance considerations

Ensure the cylinder is installed by a qualified professional and follow the manufacturer installation requirements, with the tundish positioned for occupant visibility and away from electrical devices.

Regularly check and service the pressure relief valve in line with the manufacturer standards and servicing instructions.

To prevent hot water limescale buildup within the cylinder, especially in hard water areas, consider adding a scale defender.

Water hardness map of the UK and Ireland – a lot of the country is Hard to Very hard in terms of calcium levels, which effects scale potential.

Contact us

For more details, check stock availability, lead time, delivery, price or to purchase our 210 litre indirect unvented cylinder, as we sell direct our competitively priced cylinder, which is made in the United Kingdom from duplex stainless steel with quality manufacturing methods and a manufacturer 25 year warranty (for domestic use). Please contact our sales team on 01202 822221 or use our site email contact form.

150 Litre indirect unvented cylinder

150 litre unvented indirect cylinder in duplex stainless steel from Flexiheat UK.

Our 150 litre indirect unvented cylinder is the best and competitively priced cylinder on the UK market, manufactured in duplex stainless steel with proven technology and quality manufacturing with the capacity to supply mains pressure hot water for your bathroom, shower, wet rooms, and kitchen tap hot water demands in domestic properties via a domestic hot water sealed system.

This indirect unvented cylinder is “indirect”, meaning that the cylinder has a coil within the inner cylinder, which needs to be connected and fed by electric, gas, or oil boilers. Being an unvented cylinder, you cannot use solid fuel boilers as the heat source. You must use a vented cylinder for solid fuel.

Unvented indirect cylinder 150 litre

Our 150 Litre indirect unvented hot water cylinder does not require an external expansion vessel, as it uses a patented self-sustaining internal air gap within the cylinder to account for the hot water expansion pressure that requires minimum to no maintenance.

Unvented domestic hot water self-sustaining expansion system, so no external expansion vessel is required for our unvented hot water cylinders – Flexiheat UK

What is an unvented indirect cylinder?

An unvented hot water cylinder receives its supply directly from the main water system, allowing it to produce hot water at a significantly higher pressure than a traditional vented cylinder due to its pressurisation.

Mains pressure hot water cylinders available in direct and indirect configurations.

An indirect unvented cylinder is a type of hot water cylinder that uses a primary coil to heat water indirectly, providing a safe and efficient hot water supply.

Indirect unvented cylinders are designed to work with a boiler as a heat source, providing a reliable and efficient domestic hot water supply.

What hot water demands is a 150L indirect hot water cylinder suitable for?

The overall amount of hot water used is also greatly influenced by individual behaviours. The amount of hot water used by two houses of the same size might range greatly, with one household needing twice as much as the other.

Understanding peak demands and making sure you have the ideal ratio of cylinder capacity to reheat times are the most important factors.

As a general guideline, use the following average consumption values for hot water requirements per person per day:

• Low consumption: 20–30 litres

• Average consumption: 30–50 litres.

• High consumption: 50–70 litres

Source- hotwater.org.uk

As a good rule of thumb, a 1 bedroom with 1 bathroom or a 2 bedrooms (with average water consumption) 1 bathroom property should use a 150 litre indirect unvented cylinder.

Although if the household is a high-water user, then you should look at the next size up cylinder, our 175 Litre or even our 215 Litre unvented indirect cylinder, which are detailed on this webpage – indirect unvented cylinders range

Features,specification and key benefits of our 150 litre unvented indirect hot water cylinder

• These 150L unvented indirect models are made from highly corrosion-resistant duplex stainless, ensuring a long product life and minimal maintenance.
• Note—No sacrificial anode is required for a stainless steel unvented cylinder.
• Our 150 litre unvented indirect hot water cylinder is certified in accordance with the following approvals: BBA, CE, KIWA, ISO, NSF WRC, and WRAS independent approvals.
• Quality manufacturing and proven technologies at a competitive price.
• We use a stainless-steel indirect heating coil (a heat exchanger) to speed up heat transfer, minimise heat loss, and enabling high flow rates. This corrugated coil heat exchanger provides faster reheat times compared to a standard coil indirect unvented cylinder.
• We use 60mm thermal insulation to reduce heat loss—we use reduced heat loss factory-injected polyurethane foam insulation bonded onto our highly corrosion-resistant stainless steel tank on our 150 Litre cylinder to minimise heat loss and running costs. This high-grade insulation is HCFC/CFC-free (ODP=0, GWP=1).
• Minimal heat loss: Because these units have an ErP rating, they lose less heat, which is better for the environment
• It comes standard with a 3kW immersion heater. This immersion heater is made from Incoloy for long durability that can be used for additional off-peak immersion heating, or top-up, or emergency water heating should the gas or oil conventional boiler fail.We can upgrade the 3kW immersion heater to a 6kW immersion heater if required.
• The pressure relief valve ensures safe and efficient operation of these stainless steel indirect water heaters.
• It ensures high flow rates for showers and baths in both residential and commercial settings at a maximum inlet pressure of 3.5 bar, eliminating the requirement for a booster pump.

Our 150 litre indirect unvented hot water cylinders are manufactured from duplex (the best) stainless steel and thus don’t require a sacrificial anode, which results in less maintenance time and costs for our 150 litre indirect unvented cylinders.

Our indirect unvented cylinder range allows for installation in smaller spaces because it doesn’t require an external expansion vessel. On the left is our indirect unvented cylinder, and on the right is an indirect cylinder with an external expansion vessel system, which requires a lot more space for the associated pipework and plumbing connections.

On the left – our patented internal air gap system indirect hot water cylinder – on the right – competitors similar products require an external expansion vessel which requires more space and installation time and tube and fittings.

Hot water cylinder detail for our 150 Litre unvented indirect cylinder

First we have the basic dimensions of our indirect unvented cylinder 150 Litres in capacity.

Our indirect hot water heater dimensions diagram

Dimensions of our indirect unvented cylinder: 150 liters in capacity.

Heat up times, recovery times, and weights of our 150 Litre indirect hot water cylinder—unvented model.

The above heat exchanger coil output (kW) is based on a flow temperature of 85°C. If you require higher outputs, then please see our indirect high recovery cylinder range.

Download the –Indirect and direct hot water cylinders in stainless steel brochure from Flexiheat UK

Download the –  Installation and maintenance manual for Flexiheat UK indirect and direct hot water cylinders

Standard indirect hot water cylinder unvented components

• Temperature/Pressure Safety Relief Valve: set at 90°C and 7 bar pressure (factory fitted to the indirect unvented cylinder)
• The combination (control) valve consists of a line strainer, a non-return (check) valve, a pressure reducing valve, and an expansion relief valve. Supplied loose to be fitted to the incoming cold water mains pipework to reduce the maximum inlet pressure to 3.5 bar.
• 3kW immersion heater in Incoloy (a better material than stainless steel) , which is single-phase 240 Volt powered, incorporating a control thermostat and re-settable safety cut-out. For back up hot water heating or a cheap economy electric power system.
• We have the option to upgrade the immersion heater to a 6kW version on this indirect unvented cylinder, which can be powered by either 1 phase or a 3-phase electric power supply.
• The energy cut out thermostat is set to operate at 82°C (+/-5°C).
• Motorised valve to cut the heat source plumbing to the cylinders in the event of a high temperature cut out activation of the control thermostat.

Warranty of our indirect unvented cylinder

Because this 150L indirect unvented hot water cylinder is made from high-quality duplex stainless steel, which is highly corrosion resistant.

The hot water cylinder comes with a 25-year guarantee when used in a domestic water heating application (standard household use). If used in a commercial water heating application, then the warranty is reduced to 5 years.

G3 unvented indirect cylinder install regulations

For England and Wales, our indirect unvented cylinder range is covered by Section G3 of the Building Regulations. For Scotland, it is covered by Technical Standard P3, and for Northern Ireland, it is covered by Building Regulation P5. Compliance can be achieved through a Competent Person Self-Certification Scheme, where a heating engineer with the Unvented G3 Certificate possesses the necessary knowledge and skills to install and maintain unvented hot water storage systems, or by notifying the local authority building control department.

Do not try to install or service an unvented cylinder unless you have the necessary certificate or qualifications. An unvented hot water cylinder can explode if not correctly fitted with all of the safety systems that they require.

Installation and maintenance considerations

Ensure the 150 litre indirect unvented cylinder is installed by a qualified professional and follow the manufacturer requirements, with the tundish positioned for occupant visibility and away from electrical devices.

Regularly check the pressure relief valve in line with the servicing instructions.

To prevent hot limescale buildup within the cylinder, especially in hard water areas, consider adding a scale defender to the cold water mains delivery pipe.

Water hardness map of the UK and Ireland – a lot of the country is Hard to Very hard in terms of calcium levels, which effects scale potential.

Contact us

For more details, check stock, lead time, delivery, price, or to purchase our 150 litre indirect unvented cylinder, as we sell direct our competitively priced cylinder, which is made in the United Kingdom from duplex stainless steel with a manufacturer 25 year warranty (for domestic use). Please contact our sales team at 01202 822221 or use our site email contact form.

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.

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.

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.

120 Litre direct unvented cylinder

120 Litre direct unvented cylinders in corrosion resistant duplex stainless steel from Flexiheat UK

Our 120 litre direct unvented cylinder is engineered in corrosion-resistant duplex stainless steel and is a competitively priced cylinder. We designed it to achieve high flow rates and a long product life using proven technology and a quality manufacturing process for this unvented hot water cylinder for mains pressure hot water.

We’re so sure of the quality of our 120 litre unvented direct cylinder that they come with a 25-year warranty for use in residential locations like homes, apartments, and so on. The warranty covers the stainless steel hot water cylinder for 25 years, while the other parts, like the immersion heaters, control thermostats, and so on, are covered for one year from the date of purchase, subject to conditions.

What is a 120L direct unvented cylinder suitable for?

A rough guide is that 120 litre direct unvented hot water cylinders suit flats or smaller homes with one or two bedrooms and a bathroom with one bath and/or shower.

However, people’s hot water usage patterns can vary from household to household. We prefer to give you the hot water usage data, and you, our customer, decide if it suits your hot water needs.

In the United Kingdom, we are required to keep DHW at 60°C since it eliminates the possibility of Legionella disease and is the minimum recommended water temperature.

If the stored water temperature is 60°C, the amount of required water is in red, to be blended down to 43°C (the maximum bathing temperature before scalding can occur).

Please use 10°C for England and Wales as the lowest cold-water wintertime temperature and use 5°C for Scotland and Northern Ireland.

If the incoming cold-water temperature                                            is 10°C                                   is 5°C

A bath uses around 135 litres of water at 43°C                                 89 litres                                 94 litres

A standard 8-litre shower head x 5 minutes                                     30 litres                                 31 litres

And yes, 5 minutes is the average showering time—say all the time and motion studies report.

A kitchen sink holds up to 20 litres of water                                    16 litres                                   16.5 litres

To ensure the removal of grease from dishes and cooking utensils, the standard temperature for washing up water is 50°C.

Toilet sink taps—standard type—are around 4 litres per minute; “spray” type taps are 2 litres per minute and tend to be on for a brief period.

Please see the recovery time data below for our 120L direct cylinder to establish if this is the right 120L electric water heater for your circumstances and demands.

This 120 Litre volume direct unvented cylinder is the second most popular seller in this range, however, should you wish a larger volume cylinder, which is  our most popular direct unvented cylinder that we sell, then please see the following webpage – 150 Litre direct unvented cylinder

Hot water heat-up time and recovery rates for our direct unvented cylinder, 120 litres in capacity

As standard, our 120 litre direct-pressurised hot water cylinders in high grade stainless steel are fitted with 2 x 3 kW immersion heaters with proven technology and quality.

Our 120 Litre unvented indirect cylinder has the following hot water heat-up time and recovery rates with standard 2 x 3 kW immersions fitted:

Hot water heating and recovery times

Upgraded immersion heater options 

We have the option of upgrading the immersion heaters to larger outputs for rapid heat recovery.

We can supply this 120 Ltr capacity direct unvented cylinder with 2 x 6kW immersion heaters, which can be wired in either 1 phase/240 volts (32 amps per immersion is required) or 3 phases (10.66 amps per phase is required); this will halve the recovery times stated above in the chart. We also must upgrade the standard temperature and pressure relief valve to a larger output model.

Or alternatively, you can have 1 x 6kW and 1 x 3kW immersion heater fitted, for a total kW input of 9kW; the standard 10kW T & P valve will remain if this configuration is used.

All of our unvented cylinders have a pressure test, and all are tested to 10 bar pressure and have a max working pressure of 5.5 bar.

Unvented hot water expansion system

The patented internal hot water expansion system, which uses a venturi valve to maintain an air pocket within the stainless steel cylinder, eliminates the need for an external expansion vessel. This unvented system has a long product life because it has no moving parts, which reduces running and lifetime costs.

Our internal air gap and venturi valve system used on our direct unvented hot water cylinders- no external expansion vessel is required and little to no maintenance is required for the unvented hot water system.

As a result, our direct unvented cylinders need less space, pipework and plumbing fittings, making the installation process simpler and lowering both costs and time required for installation.

Unvented Direct Cylinder 120 Litres: Features and Benefits

• Enhanced Venturi valve technology, which automatically replenishes the internal air gap within the unvented cylinder.
• Dual immersion cylinder: 2 x 3kW immersion heaters as standard.
• 3 bars of water pressure at the outlet (subject to incoming pressure).
• Mains pressure hot water directly delivered—enabling high flow rates.
• No expansion vessel or moving parts, ensuring low maintenance.
• ErP “B” heat loss rating for reduce energy consumption
• Benefits from an evolved design and quality manufacturing for improved performance at low flow rates.

120 litre unvented direct cylinder dimension

Our 120 litre stainless steel direct unvented cylinder has the following dimensions:

Unvented direct hot water cylinders – Dimensions drawing for 80 Litre to 500 Litre models

The highly corrosion-resistant duplex stainless steel 120 Ltr capacity direct unvented cylinder has the following engineered dimensions in mm:

130L Direct pressurised hot water cylinder details highlighted in red – yes, we give you 10 more litres of capacity for free, as they can hold / have 130 Litres of capacity.

Our duplex stainless steel cylinders are available in both direct and indirect configurations as you can see in the following manual 

Download the installation & technical manual for our direct and indirect hot water cylinders

Unvented direct cylinder 120 ltr approvals

Our 120 ltr direct unvented cylinder we sell has been approved by the CE, BBA, and WRAS independent approvals (Water Regulations Approval Scheme—a certification body for domestic hot water heating products that assists businesses and customers choose safe products that comply with hot water regulations) and benefits from ISO, KIWA, and WRC approvals as well, proving the quality manufacturing process of our stainless steel cylinders.

Components supplied with our stainless steel unvented cylinder: 120L direct unvented cylinder

2 x 3kW immersion heaters manufactured in incoloy (a super austenitic stainless steel—with high resistance to oxidation), with a control thermostat and high-temperature thermal/energy cut-out thermostat.

Front access to the controls on our electric pressurised hot water cylinder.

A temperature and pressure relief valve to comply with the hot water unvented cylinder regulations.

A complete pressure-reducing valve combination valve/6-bar expansion relief valve (the maximum inlet pressure to the mains pressure hot water cylinder) for the cold water mains inlet 

A Tundish: A Tundish has a clear window that allows you to see if water is flowing from the pressure relief valve (PRV). This helps you identify potential issues with the unvented hot water system.

Heat loss ErP rating for this direct unvented cylinder

This direct unvented cylinder has an ErP level of “B” for the thermal insulation to reduce heat loss and ensure running costs are kept to a minimum, which is an excellent rating for an unvented direct cylinder.

The injected polyurethane foam thermal insulation, with an ODP=0 and a GWP=1 rating, is free of CFC/HCFC and provides 60mm of fire-retardant protection. Similar competitor products only have 40 mm insulation to reduce heat loss, and thus the ErP insulation ratings are lower than our direct unvented cylinder.

Delivery of the unvented cylinder

We deliver these direct unvented cylinders on a small pallet delivery service that comes on a lorry directly, with your responsibility to offload. We can upgrade the delivery service to have a tail lift at request to get the stainless steel 120L direct unvented cylinder to floor level.

Contact Flexiheat UK

Please contact us at 01202 822221 to answer any questions or use the company site contact email form to get more information or details, the current stock situation, delivery options, or a cost on the best 120 litre direct unvented cylinder/120Ltr unvented direct cylinder models on the UK market. These are manufactured from high-grade duplex stainless steel (a high-grade stainless steel), with a 25-year warranty, with WRAS independent approvals, have a built-in expansion system, and are a competitively priced cylinder.