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hydronic heating, commercial heating

Condensing Boilers: Energy Efficient Technology

With a range of highly efficient commercial boiler options Hunt Commercial has to offer, it can be confusing to understand what product best suits your project.

It is, however, worth noting that the National Construction Code 2019 (formerly the Building Code of Australia) mandates the thermal efficiency of new gas fired boilers used for; Space Heating, Pool and/or Spa Heating, must be NO less than 86% efficient (Type-A, under 500mj/h consumption) or NO less than 90% efficient (Type B, above 500mj/h consumption).

Regulations in European countries for many years now have also dictated that non-condensing type boilers are NOT to be installed as retrofits or within new builds, due to their lack of efficiency.

With these facts in mind, it’s clear that condensing boilers are the preferred choice, whether for residential or commercial installation.

This article covers:

  • What is a condensing boiler & how does it work?
  • Applications for commercial condensing boilers
  • Benefits of using a condensing boiler
  • Condensing boiler product options
  • Government Grants and rebates


hydronic heating, condensing hot water boiler

What is a condensing boiler & how does it work?

Also known as condensing hot water heaters, condensing boilers are highly efficient, up to 108%. Whereas their inefficient counterparts, conventional boilers, are typically only 80% efficient or even less.

Condensing boilers are designed to extract as much energy as possible from the combustion process, where hot flue gasses play a large part in the water heating cycle, by pre-heating the cooler, returning system water and therefore reducing flue gasses to approximately 65deg C. Consider that the flue gasses discharged from a conventional boiler can be greater than 200deg C, ultimately leading to a considerable waste in energy.

Applications for commercial condensing boilers

Condensing boilers are widely used in Australia, across a wide range of applications;

  • Commercial office buildings
  • Schools
  • Hospitals
  • Hotels
  • Shopping centres and retail stores
  • Fitness and leisure centres
  • Aquatic centres
  • Wineries
  • Dairy Farms
  • Nurseries

What are the benefits of using a condensing boiler?

Selecting the right boiler option is paramount, benefits of using a condensing boiler include:

  • Increased energy efficiency
  • Lower carbon footprint
  • Cheaper running costs
  • Safety

A typical condensing boiler has a thermal efficiency of 95%+, compared to efficiencies of around 80% for non-condensing models. It’s also important to note that an older non-condensing boiler efficiency declines dramatically over time.

A key part in the thermal efficiency of a condensing boiler depends on the heating flow and return temperatures of the water within the overall system. Condensing boilers are designed to use the latent waste heat in flue gasses to achieve their highest efficiencies, in order to maximise this process, the optimum returning system water temperature needs to be below the dew point of water, 55deg C or below, where the lower the return temperature the higher the boiler efficiency.

Therefore, when designing systems, it is advisable to select design conditions that optimise the performance of condensing boilers i.e. low flow and return temperatures.

Lower carbon footprint

Installing a condensing boiler opposed to a conventional boiler will significantly reduce carbon emissions, with a saving of up to 1,200kg of carbon per year. In the UK where boiler heating systems have been widely used for many years; it is mandatory for all old boiler replacements to be condensing boiler due to the comparative environmental benefits.

Cheaper running costs

While maybe costing slightly more initially, condensing boilers are the logical option in the long-run due to their high energy efficiency, resulting in lower running costs. By reaching up to 108% efficiency, condensing boilers can help lower bills significantly.


Modern condensing boilers have a multitude of safety devices ensuring complete safety whilst in operation, these include; flame safeguards, over heat thermostats, air pressure switches, pressure relief valves etc.

Boiler product options

It’s important to select to correct boiler of the project and design conditions. Hunt Commercial offers both wall hung and floor standing boiler boilers to suit your project.

hydronic heating, commercial heating


Wall hung boiler units

Coming in a wide range of outputs, wall hung condensing boilers can be wall or frame-mounted, with options available for both internal and external applications.

Hunt Commercial currently offers the following wall hung products from the Immergas range suitable for a range of applications and plant room layouts. Modular or single boiler options available.

Floor standing boiler units

Hunt Commercial proudly offers the Idea Imax range for floor standing condensing boilers. Designed with ease of installation in mind, a small footprint saves important space in plant rooms. Their minimal width means they can fit through a standard sized doorway, making them great for retrofits and replacements.

Contact our commercial team for advice on selecting the best boiler option for your project

Grants, rebates & financial assistance

There are several organisations in Australia that are working towards reducing energy consumption. It is well worth exploring the financial incentives on offer for individuals and organisations, including:

Australian Government statutory authority formed to ‘facilitate increased flows of finance into the clean energy sector’. It draws on expertise, extensive networks and market reach to make it easier for businesses and consumers to secure finance to transform their energy use.

Reduces energy consumption in NSW by creating financial incentives for organisations to invest in energy savings projects

A range of energy programs are on offer via the Australian Government to support households and businesses. Visit their site to discover current incentives and offers in place.

If you’d like some expert advice on selecting the best boiler option for your project, contact our commercial team now.

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