What are the benefits of a boiler cascade system?

When you have a site that requires a high output, you have the option to install a single large commercial condensing boiler or several smaller boilers in a cascade. 

In commercial applications with large energy usage, high-efficiency condensing boilers can achieve several megawatts.  Our Imax Xtra EL is available in 1240kW outputs as a dual unit, for example, and our Evomod will achieve an output up to 1MW from a single unit solution. 

When multiple boilers are installed in cascade, they work together to achieve the same output as single larger boiler.  Each boiler is allowed to modulate up until the demand requires output from a further unit, and so on, until the demand is met.  With our Imax Xtra 2 boilers, up to four can easily be cascaded for 1120kW output.  Want to see how boilers in cascade look in 3D?  Click here to see Evomax 2 in cascade.

Whilst installing a single larger boiler might at first seem to be the simplest solution to meet the output required, a cascade of boilers has several benefits:

1. Cascading commercial boilers have a high modulation rate

Cascading boilers have a very high modulation rate as the turn down across the total cascade increases with the number of boilers used, e.g. one boiler has a turn-down of 5:1, for each additional boiler in a cascade that is controlled sequentially you increase the turn-down by 5:1. So for a cascade of four boilers controlled sequentially you can achieve a turn-down of 20:1.

2. A cascade of commercial condensing boilers saves space

Installing several smaller boilers in a cascade can create space in a plant room as they can be placed against a wall with no clearance between the boiler and the wall.  It often also makes it easier to get the boilers into the plant room in the first place.

3. Cascading makes for a highly efficient commercial boiler solution

In commercial applications, demand for heating and hot water can vary considerably over a day, and often in unpredictable patterns.  A single boiler will cycle on and off as the demand changes, but this is inefficient and places strain on the equipment which could reduce its lifespan.  Multiple boilers operating in cascade, on the other hand, have a higher modulation ratio, so there is less need for each individual boiler to cycle on and off.  Essentially, the work is shared equally between the boilers in operation for a more reliable, long-lasting, highly efficient commercial boiler solution.

4. Why does cascading a boiler system help to avoid downtime?

If you have a single boiler and it breaks down or has to be switched off for maintenance, all your heating and hot water have gone.  In a cascade system, if a single boiler fails, the system as a whole remains in operation with the remaining boilers taking up the slack.  When it comes to routine maintenance, each boiler can also be taken offline independently of the others, again allowing for continuation of supply.  

How to use a cascade configurator to make choosing what you need easier

Clearly, installing multiple boilers in cascade as opposed to a single boiler requires more pipework and flues, plus there’s controls to consider.  Thankfully, we have made this process very straightforward through a range of kits and tools:

Header kits: available in standard or low height to suit all plantrooms, inline or back-to-back for quick and easy installation. 

Multiline Flue kits: allow boilers to be connected via a common flue header in Type B23 open flue installations.

Integrated Cascade control: available for certain models, this simple plug in card gives you the ability to sequence and cascade boilers independently without a complex Building Management System.

Cascade Configurators: available for the wall mounted Evomax 2 and Imax Xtra 2 – make choosing what you need straightforward. Simply answer a few quick and easy questions covering: height and how the boiler will be hung; gas type; number of boilers and output; type of hydraulic separation, if required; insulation.  The work is done for you, and all you need do is download the information as a PDF or get it emailed to your inbox.

If you would like to find out more about Ideal Heating’s UK manufactured commercial boiler cascades visit: https://idealcommercialboilers.com/evomax2-cascade-configurator

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