Commercial indirect hot water cylinders

Commercial indirect hot water cylinders differ from domestic hot water cylinders for homes in two main areas –

1. They have larger capacity heating coils for higher domestic hot water performance as well as a larger water storage capacity.
2. They have a cleanout port/inspection port so that the internals of the hot water cylinders can be cleaned and inspected as part of the HSE risk of exposure to legionella (credit – the Health and Safety Executive of the UK government; see more here) in commercial properties.
   

There are particularly stringent regulations covering legionella control for commercial buildings, leisure centres and healthcare facilities. Generally, a commercial domestic hot water heating system requires hot water cylinders to have an inspection/clean-out port as specific requirements, especially in hard water areas for indirect water heaters.

Here is an extract from the NHS England safe water in health care premises document

 

Flexiheat has an extensive range of commercial indirect hot water calorifier’s to supply hot water to meet your specific requirements, with unvented cylinders /unvented system being the most popular option for a domestic hot water heating system.

Sizing your commercial indirect hot water tank / calorifier?

Sizing the correct commercial indirect hot water tank for your requirements: simple, please see this webpage – How to size a commercial water heater

Glass lined mild steel indirect domestic hot water cylinders

Glass lined mild steel cylinders are another option, providing a cost-effective solution for commercial hot water needs. They are to be used in medium- to hard-water areas when cost-effectiveness is an issue.

Glass lined units must not be used in soft water areas.

Manufactured to high standards, these commercial indirect DHW cylinders are designed to deliver a reliable and efficient hot water supply.

These tanks are designed and suitable for 10 Bar working pressure for the 200 to 1,000 litre hot water cylinder models and 8 Bar for the 1,500 and 2,000 litre models. Higher working pressures are available at request.

All of these tanks are easy to install and are ErP energy class rated A, B or C, depending on the volume of the hot water cylinders in question to keep running costs lower.

Stainless steel indirect domestic hot water cylinders

Stainless steel cylinders are a popular choice for commercial hot water systems due to their durability and resistance to corrosion. Stainless steel indirect commercial cylinders must be used in soft water areas.

Stainless steel commercial cylinders have taken over from copper cylinders, as they offer a high level of performance when it comes to pressure ratings of the tanks; many copper-manufactured hot water cylinders are rated only to 3 bar, whilst the stainless versions are either 6 or 10 bar working.

This higher pressure rating is often necessary for commercial water cylinders used in office blocks, since the static hot water working pressure of a high-rise building typically exceeds 3 bar or 30 metres of head.

Thus the selection or use of stainless steel cylinders can cover these higher pressure requirements.

Indirect glass-lined commercial hot water cylinder range details

Available from 150 to 2,000 litres, the following is an overview of the products we can supply. Showing coil power outputs at 80°C/60°C flow and return temperatures to the heat exchanger coil.

The standard DIN 4708 shows the water performance for 10°C to 45°C – this is a continuous flow rating as such.

Download the 150 to 2,000 Litre Commercial indirect domestic hot water calorifiers / cylinders brochure from Flexiheat UK 

For any other heated water storage temperatures, such as 60°C, which must be achieved in the UK in commercial water heating, the formula is:

Volume (litres) = (Heat (kW) x 3600) / (Specific Heat of Water x Density of Water x Temperature Rise (°C)).

For water, the specific heat is approximately 4.184 kJ/kg·°C and the density is 1 kg/L. Therefore, the formula simplifies to Volume (litres) = (kW x 3600) / (4.184 x Temperature Rise). 

Here is the output data for an 80°C/60°C flow and return to the coil – raising cold water from 10°C to 60°C – for the above hot water cylinders.

 

Model	150	200	300	400	500	600	800	1,000	1,500	2,000
Coil kW rating @80C/60C	24	36	44	55	55	63	68	88	94	112
Litres of hot water @60C	413	620	757	946	946	1,084	1,170	1,514	1,618	1,927

Commercial stainless steel indirect cylinder range

Our stainless-steel range of indirect commercial water heaters, we have both the single coil and twin coil versions show on one data table. Here is the technical data –

 

Download the commercial stainless steel indirect domestic hot water heaters 150 to 2,000 Litres from Flexiheat UK

 

Here is the output data for an 80°C/60°C flow and return to the coil – raising cold water from 10°C to 60°C – for the above stainless indirect hot water cylinders.

Stainless Models	150	200	300	400	500	600	800	1000	1500	2000
Coil kW rating @80C/60C	12	19	29	34	43	43	50	60	88	120
Litres of Hot water @60C	207	327	499	585	740	740	860	1,033	1,514	2,065

Inspection and clean out flange detail

Detail of the inspection and clean out port on our energy efficient indirect water heater tanks – please note tapping “4” is an immersion heater port, for back up to an oil or gas boiler heat source to the heating coil or for top up or additional heating power which is often required for a heat pump heat source hot water heating system.

Additional immersion heater option

We can also supply the clean out port blanking plate with a screwed connection for an additional immersion heater, thus a maximum of two immersion heaters can be fitted to this extensive range of indirect commercial hot water cylinders.

Unvented commercial cylinders or Vented commercial cylinders

Both ranges of our indirect commercial water heaters can be used as either unvented cylinders or vented cylinders. We recommend using our stainless steel versions for open-vented domestic hot water cylinders because these systems tend to allow more air ingress from the cold water tank and vent pipe, necessitating the best possible corrosion resistance.

However, these days unvented cylinders (fed directly from the cold water mains – thus an unvented system) are by far the most popular hot water calorifiers we get asked for.

For unvented cylinders we just supply a potable water unvented kit to suit the appropriate indirect cylinder volume with a thermostat (with control and high limit thermostat with manual reset) and 2 port control valve to isolate the heating coil in the event of high limit thermostat activation.

Types and Specifications of Indirect Cylinders

• Indirect cylinders are available in a range of sizes and capacities, from 150 litres to 2,000 litres, making them suitable for a variety of commercial applications.
• These cylinders are designed to work with a range of heating systems as a heat source, including gas boilers, solar panels, and heat pumps, providing a flexible and efficient solution.
• Buffer vessels are also available, providing additional storage and capacity for commercial hot water systems. Please see our dedicated webpage on these domestic hot water buffer vessel range here – Domestic hot water storage tank or vessel
• The specification of these cylinders includes details such as diameter, height, and working pressure, making it easy to find the perfect solution for your business.
• With a range of products to choose from, you can find the ideal hot water cylinder to suit your heat source and provide a reliable supply of hot water.

Indirect commercial hot water cylinders

Should you require any more assistance or information on our commercial indirect hot water cylinders in stainless steel or glass lined steel options, which are perfect domestic hot water cylinders for commercial properties or applications, please don’t hesitate to contact our sales team on 01202 822221 or click here for our email contact form page.