Show Menu

Hydronic Boilers

H2O Heating promotes the use of hydronic heating boilers from leading European manufacturers who have a proven reputation offering exceptional performance from highly efficient products that help towards reducing our impact on the environment through reducing greenhouse emissions.

immergas-logo_web With over 50 years’ experience and over 5 million boilers installed worldwide, Immergas is very much a reputable and reliable Italian manufacturer producing the latest cutting-edge hydronic heating boilers – as they themselves say innovation was the spark that started Immergas” back in 1964. In fact, the reliability of their products is their primary requirement at all times; their ethos is for people to be able to count on the products they purchase and this continues today.


BaxiLogo_web Baxi, one of Europe’s leading manufacturers, and a familiar household name in the UK have been providing warmth to homes since 1935. Their continuing commitment to developing innovative products using the very latest technologies has led to major awards in the UK such as Energy Efficient Product of the Year” in 2014; 'Queen’s Award for Enterprise in Innovation' in 2012 and 'Green Manufacturer of the Year' in 2011.


SimeLogo_webSime, founded in Legnago Italy in the early 1970’s, has spent the past 40+ years continuously investing in the research and development of cutting edge. Manufactured in Verona, Italy, they currently supply boilers to over 60 countries around the world; introduced into the Australian market in 1982 they have established themselves as one of the market leaders, one of the top 10 in Europe, in high quality, high performance, energy efficient hydronic heating boilers offering reliability and comfort.

What is a Hydronic Heating Boiler?

Hydronic heating is simply the use of water, as opposed to forced warm air, to heat your home. An efficient central hydronic boiler heats the water at its source that is then circulated throughout the building using a network of pipes to an outlet; an outlet can be a radiator panel, in-floor trench convector, in slab floor coil or a combination of the available outlet options. Once the heated or used water has passed through the system it is returned to the boiler to be reheated; the water is constantly recycled and circulated through the system having no further demands on water usage apart from only requiring a small amount of water to top up the system at yearly service intervals.

Most of the major components of a hydronic heating system are contained within the boiler making installation easier and tidier, and there is also flexibility of siting the boiler itself, the normal and usual siting position of the boiler is external, with the use of a protective external cover, alongside the hot water service, however, if this is not possible then the boiler can be installed internally such as in a garage or basement.

The Hydronic heating boilers we install are fan flued appliances, this means they draw the exact amount of air required from outside to enable a clean and efficient burn of the gas, making them safer, cleaner and more efficient than the old natural draft boilers in operation.

Hydronic boilers come in a wide range of outputs and at H2O Heating we will calculate the size required based on the requirements of the individual home both now and in the future. Most boilers are modulating meaning they will use only the amount of power required to provide the heat and or water demanded. For large properties, it is possible to link more than one boiler together to provide the right amount of heat.

There are essentially two types of hydronic boiler a heat-only system boiler and a combination heating and hot water boiler. Both of these boilers are available in standard efficiency and high-efficiency options.

Heat Only System Boiler

If you live in a property with a high water demand (more than 2 bathrooms) then a Heat Only boiler is the option combined with a separate unit for hot water. A Heat only boiler will pump hot water to the radiators (or underfloor pipe or trench unit or combination of) to meet any demands for heat.

Heat only system boiler brochure Heat only system tech info

Combination Boilers

Combination boilers have been highly popular in Europe for many years and are the UK's bestselling type of hydronic boiler as not only do they heat the hydronic heating system they also provide all hot water requirements from one product – no need for a separate instantaneous hot water unit. The hot water is delivered at mains pressure and a combination boiler will only heat the water when a demand is put on it such as when a tap or shower is turned on.

However, combination boilers are only suitable for properties with only 1-2 bathrooms this is because the water flow is reduced when more than one tap/shower is operational, making them ideal for smaller properties negating the additional cost of a separate water heater.

Combination boiler brochure Combination boiler Tech Info

High-Efficiency Condensing Boilers

The principle behind a High-Efficiency Condensing boiler is the recovery and re-use of wasted heat that is normally expelled into the atmosphere through the flue. Due to their advanced technologies, they release low NOx and CO2 emissions.

How does a condensing boiler work?

Condensing boilers are designed with a larger or in some case a dual, heat exchanger that extracts the normally wasted heat from the flue system re-circulating it around the heat exchanger. This new technology ensures that as little heat as possible is lost through the flue gases. This process of secondary heat extraction reduces the temperature of the expelled gases and causes water vapour to be formed by condensation and drain away.

Cost Savings

A condensing boiler by its very nature extracts much more usable heat from its fuel than a non-condensing boiler offering savings on running costs: a standard efficiency boiler will give on average a 83% efficiency (depending on the model selected) whereas a high-efficiency boiler with its increased technologies will give up to 97% efficiency. A condensing boiler will be between 10% - 15 % more efficient than new standard efficiency boilers and up to 30%-35% for boilers that are 15 years and older, put simply you could save up to 35% of fuel you purchase just by changing to a new high efficiency condensing boiler and this saving increases further if you are on LP Gas.

Incorporated technologies such as constant temperature monitoring allow for increased operating efficiencies.

At H2O Heating we will advise you on whether a condensing boiler is an economical option not only to improve the efficiency of your system but also with regards to the outlay cost.

High-efficiency boiler brochure High-efficiency boiler tech info

Boiler protection

To increase the longevity of your new hydronic boiler there are a number of recommendations such as the power flushing of an existing system (not required on a new system); installation of a magna clean in-line filter; liquid inhibitor – in fact when installing an Immergas InTec System boiler with a premier pack which includes a controller; magna clean and inhibitor the warranty on the boiler will be increased from a standard 3 year to 5 year manufacturer’s parts and labour;* well worth the investment. For more information see the information page on Hydronic controls and components.
*terms and conditions apply

Powerflushing is the method of connecting a large pump machine to the existing hydronic system and using clean agents, removing all existing dirt and debris from the pipework and system, prior to installing the new boiler. By doing this, it will negate any impurities damaging the new heat exchanger of the new boiler and prolong its working life. Powerflushing is highly recommended and in fact, stipulated in the UK for replacement boilers.