Condensing gas boiler technology for central heating

If you have a boiler in your home, you might be interested to learn that condensing boilers are slowly but surely replacing older designs in the powering of domestic central heating systems. This is happening especially in Europe but is filtering around North America and down to Oceania.

The switch to condensing boilers has been strongly advocated by pressure groups and government bodies who are concerned with reducing energy use. In comparison with conventional boilers, gas-fired condensing boilers do not only optimally utilise the supplied energy but, they also utilise the thermal energy contained in the flue gas, which is otherwise lost through the chimney.

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What makes a condensing boiler different to a non-condensing boiler? Both types of boilers heat water through the heat of combustion. With a non-condensing boiler, the resulting flue gases are normally passed into the chimney and, as a result, the energy contained in the flue gas is lost. However, condensing boiler technology exploits these gases, which consist to a large extent of hot water vapour and extracts the flue gas heat and then feeds the energy obtained into the heating circuit.

The water vapour must condense in order to gain energy. This is temperature specific and a condensing boiler works well at a temperature of below 56 °C. The condensing boiler cools the steam through a specially designed heat exchanger. The energy gained is then used to preheat the cold heating water. The hot water then passes into the primary heat exchanger where it is heated further to reach the desired temperature. During this process, small amounts of waste water occur which must be disposed of. The waste water has very low amounts of acidity and requires no processing before it can be drained into a normal drainage system.

Condensing boilers achieve a much higher efficiency than non-condensing boilers and thereby reduce your heating costs and emissions. A basic rundown of benefits from a condensing boiler are:

  • Optimum energy efficiency of up to 98%
  • Significantly less soot and particulate matter during combustion via condensing technology
  • Consumption drops by up to 30% compared to an old heating installation
  • Low investment costs
  • Flexible expansion, e. g. with solar collectors, heat pumps, storage and controls

When talking about the high efficiency of 98 % of condensing boilers, the value refers to the “upper heating value”. Technicians in the boiler industry usually make their calculations using the “lower heating value”. The lower heating value is the amount of heat that can be utilised in the combustion of an energy source, without causing condensation. The lower heating value therefore only contains a portion of the total fuel energy and does not give a full picture of the efficiency of a product.

The upper heating value will also include the amount of heat contained in the flue gas and water vapour which can be utilised by condensation. The efficiency of a boiler is also called standard efficiency, and this can reach a maximum of 100% in the ideal case, when calculated on the basis of the upper heating value.

If you install a condensing boiler there may be the need to supplement your existing chimney with a small plastic pipe. These can be easily fitted to existing chimneys as they have a very small diameter.

New technology always has its advantages over old technology and installing a condensing boiler in your home will see you benefit from:

  • Space savings: Condensing boilers don’t need a hot water tank and are available in a wide range of compact sizes, making them much sleeker and convenient to fit in a kitchen cupboard when compared to conventional models.
  • Supply reliability: New boilers are all fitted with a heat exchanger made from a non-ferrous metal, usually stainless steel, so that they don’t corrode over time. There is no need to wait for the hot water cylinder to refill, either, so hot water is available in unlimited supply.
  • Simple controls: Conventional boilers tend to operate fairly simply, with either a temperature on/off switch of a controller with a few standard heating options. However, condensing boilers don’t need a timer, as they automatically produce hot water whenever a tap is turned on.


Whether running in condensing mode or not, a condensing boiler will always be 15-30% more energy-efficient than its conventional counterpart, helping you to reduce your energy bills while limiting the impact of your domestic heating on the environment.


As long as your new condensing boiler is properly installed and maintained by a certified gasfitter, it will undoubtedly prove to be a reliable, cost-effective and energy-efficient investment for your home.

Changing the New Zealand mind set around Heating

We all fear change in our lives. Change takes us somewhere we are not comfortable with. Somewhere new often leads us to something exciting and rewarding. We all need to embrace change at some point in our lives.


For years the term Central Heating in the northern Parts New Zealand would have been a luxury for wealthier home owners. Over the years, different types of heating have been used to varying degrees offering most homes a solution. These solutions work reasonably well for some situations but have inherent and obvious draw backs. Many households rely on portable heating solutions. Often costing a small fortune to run and barely doing the job they are intended for. Consuming large amounts of power for small returns in comfort, they are a source of danger in the home requiring supervision for the more vulnerable members of the family and giving an increasing the risk of fire.

Single heat pump systems can offer single room solutions for an affordable cost, although mostly retro- fitted with no consideration for home design. These units under perform ensuring families are huddled into a single room at colder times of the year, leaving the rest of the home to feel cold and damp.

Centralized blown air systems have gone a way to battle this offering homes with a neater solution. The main issues with any kind of blown air system is the way they warm areas, effectively blowing warm air around a room creating drafts and cold spots. These forced systems have another drawback in the way household dust is disturbed around the home, being more likely to magnify respiratory conditions such as asthma.

Kiwi home owners are now looking for more comfort and greater control over their home heating. Not just “making do” as past generations have but truly creating homes which are light and airy in the summer and warm, dry and cosy in the winter.

With modern central heating solutions now becoming an affordable way to heat homes more and more householders are using Radiant heating as their first solution. With solutions for new homes and renovations, Central Heating will become the norm, leaving behind the cold damp homes of the past.

Underfloor Heating Systems warming from the feet up. There’s nothing like putting a bare foot onto a normally cold tiled floor and feeling the warmth, instantly feeling cosy. Underfloor heating gives the ultimate in radiant comfort. Rooms are evenly warmed with no cold spots.

Hydronic Radiator Systems offer a cost effective retrofit and new build solution for many New Zealand homes. Radiator heat emitters warm rooms using natural convection air currents, giving an even dry warmth with modern individual control. This solution is ideal for homes with different temperatures required in different areas. Bedrooms and living spaces can be controlled to provide different levels of warmth for each user.

With a Radiant Heating solutions, warmer dryer homes provide the added benefit of helping to alleviate respiratory conditions creating a healthier home environment. No more cold beds at night, no more damp feeling clothes in the morning. All rooms in the home will be freed up for use in the winter.

With little or poor information on Radiant Central Heating solutions to the consumer, many households are still relying on out of date inefficient solutions for their homes. Changing aging mind sets for the future of Kiwi homes is key, creating warmer, dryer, healthier homes giving future generations the levels of comfort found in European homes. With greater supply and demand manufacturers are now looking to New Zealand as a growing Central Heating market. German Band boilers such as Bosch and Valiant being offered at attractive prices. With an increase in skilled heating technicians and companies realising the benefits of Hydronic Central Heating, the future of central heating in New Zealand looks bright.

Is Ducted Heating “Central Heating”?

Ducted heating systems are a common form home heating system that utilize a heat pump and ducting to transfer the heat to various rooms within the home. Ducted heating systems provide many benefits.


The benefits of ducted systems include:

  • Ducted systems are easily integrated with a ventilation system
  • Provide high performance and excellent cooling ability
  • Near silent operation
  • Provides even temperature throughout the entire home, eliminating cold and hot spots.
  • Adds value and luxuriousness to your home

But, is a ducted heating system considered a central heating system? In New Zealand, ducted heating systems are, in fact, considered central heating systems. However, in other parts of the world, such as Europe, central heating is more used to refer to radiant heating systems. So what’s the difference?

The graph above shows the difference of air flow between radiant and ducted heating systems. The heat pump graph on the left will relate to the ducted system.

Radiant heating systems work by supplying heat directly to the panel in the wall, floor or ceiling in the house, most commonly a radiator. They depend on the principle of radiant heat transfer, delivering heat from a hot surface to the object and people within the room through the means of infrared radiation.

The benefits of radiant heating systems include:

  • Can be more efficient than ducted systems due to no heat loss in the ducts
  • People with allergies can use radiant heating
  • Radiant heating uses less electricity, especially useful for off grid homes.
  • A wide range of sources can be used to create heat including oil fires, wood fires, solar and more.

Which time of system is best for your home? Give us a call today to discuss on 0508 446 892.




Types Of Underfloor Heating Systems

When it comes to underfloor heating systems, there are two main types that you can choose to utilise in your home, electric and hydronic. In this post we will discuss the differences and the benefits of each system.

Electric Underfloor Heating

Electric underfloor heating systems are used only for heating and make use of flexible heating elements such as cables, mats or bronze mesh to transfer the heat. B3ecause they are low profile, they can be installed in a thermal mass or right under the floor finish. They are often used as carpet heaters, portable heaters for under rugs, and other floor warming systems such as shower floors and seats.

Electric systems tend to be simpler to install and commission than hydronic systems, but large scale systems require skilled tradespeople and designers.

Hydronic Underfloor Heating

Hydronic underfloor heating systems use water or a mix of water and anti-freeze as the heat transfer fluid that is passed through a “closed loop”, recirculating between the floor and the boiler.

Hydronic systems require skilled designers and tradespeople familiar with the system components including boilers, circulators, control, fluid temperatures and pressures. Using modern factory assembled sub-stations can simply the design and installation efforts greatly. These are used primarily in direct heating and cooling.

Hydronic systems use a single source or can use a combination of energy sources to produce the heat and manage energy costs. The most common options include:

  • Boilers:
    • Natural gas
    • Methane
    • Propane
    • Coal
    • Oil
    • Electricity
    • Solar thermal
    • Wood or other biomass
    • Bio-fuels
  • Heat pumps and chillers:
    • Electricity
    • Natural gas
    • Geothermal heat pumps