By opting for a condensing boiler to convert energy of natural gas to heat your home or apartment you are not only helping yourself by saving on heating bills but also make possible environmental well being while helping the whole world.

Wasted energy = wasted money
Condensing boiler whatever the fuel type may be, is said to be efficient about 90% at the lower end and – 98% at the upper. Your 15 year or so old traditional oil fired boiler is at least 12% less efficient than this. Whether it is gas or oil, you can imagine how much fossil fuel the high efficiency condensing boiler would conserve, how much CO₂ emission it would curtail and the pile of moolah you would save during the next 30 or 40 year plus life span.

What makes a condensing boiler more efficient?
A traditional gas burning boiler or a condensing boiler of recent vintage technology is not different to any oil burning boiler in basic working mechanism. The extra bit of efficiency in condensing boiler is due to the condensation of water of combustion from steam state to liquid, releasing the latent heat of vaporisation. (Sadly if not for the condensing boiler, this huge percentage of heat energy will be sent up through the chimney as flue gases, without the home owner having a clue to what’s happening). Inherently any condensing boiler can achieve fuel efficiencies of 90% upwards easily.

System Technology
A centralized heating system, incorporating a condenser boiler depends on several other system components. These would include the control system, DHW cylinders, Terminal units such as radiators etc. Unless there is a collectively efficient system in operation the ultimate overall efficiency will not be as desired.

Proprietary Brands and advanced designs
Proprietary brands such as Viessmann, a world leader in this field have developed technologies such as their stainless steel Inox-radial heat exchangers for natural gas combustion, capable of extracting almost to the end of last wave of thermal energy otherwise just wasted. Vitotronic controls (microprocessor based control system), Vitocell domestic hot water cylinder, lambda pro control combustion controls (a metering system that adjust the combustion process to the properties of any gaseous fuel) are other advanced features developed by them. The ultimate result is a very welcome consistent fuel efficiency of about 98%.

Greentech.ie will provide you guidance to achieve high energy efficiencies in Viessmann and other Condensing Boilers.

Condensing Boilers, whether oil or gas burning, are about the most energy efficient Central Heating System boilers in buildings. The efficiencies typically may run as high as 98 % according to claims by the manufacturers. The same items on test beds of units of certifications according to for example SEDBUK of UK , on the other hand would show this to be around 95 % at best. In real life this can be typically about 82 % – 89% and would be about 90% at optimum operation. Bear in mind that all these efficiencies are worked out when High Heating Value (HHV) fuels are used and test conditions are near ideal.

In comparison In Conventional Boilers the efficiencies ranging from 70 % to 80% in operation. At that efficiency the near 50% capital cost increase of a new condensing boiler and controls is hard to justify. But is this inference correct?
To really understand the real economics encountered one must have a look at the working of a condensing boiler.

Working of a Condensing Boiler

A hot water boiler is a vital component of a central heating system of a building. A traditional boiler makes use of  the hot temperatures of  flue gases  generated  as a result of  burning of fuel oil or gas in the burner and combustion chamber, to  heat up the circulating hot water in the central system .This  is made possible by the use of a heat exchanger through a process akin to that of a car radiator. The combustion of hydrocarbon fuels also produces water as steam among other by products which is exhausted to the environment after passing through the heat exchanger to transfer the thermal energy to the heating system water.

In a conventional boiler it is a single pass and then out through the chimney or any other vent.

In the condensing boiler as the name implies, a condensing process is additionally incorporated. What condenses is the water in gaseous form (steam) generated within the combustion chamber. What you gain is the latent heat (of vaporization) released at the condensation of steam to liquid water. A note worthy fact is that, the water thus condensed is highly acidic and corrosive.

Efficiency of  Oil burning condensing boilers

Manufacturers estimate their products can be fuel efficient up to about 98%. In practice the average efficiency is not more than 90%. This increase of about 12% in efficiency  over the traditional boiler  will conserve a considerable quantity of fuel oil over an year  thus  also making  it easy on your purse. Naturally the lesser oil burnt means lesser harmful emissions, better carbon foot print and cleaner air. Installation or retrofitting condensing boilers therefore entitles your t building for monetary grants, improved energy rating  etc. from almost all state or any other  sustainable energy agencies.

Overcoming the low efficiency

Makers of condensing boilers are constantly finding ways to improve energy efficiencies, durability and reliability of their products. Viessmann one such leading manufacturers of condensing boilers in the western world, has developed techniques to overcome some major draw backs and also improve the efficiency at almost all temperatures.

Their heat exchanger of oil burning boiler is designed for 3 passes making it extract more thermal energy of combustion. The use of microprocessor controls to sense outdoor temperature variations and adjust the combustion process/ boiler water accordingly to optimize oil usage further improves efficiency Viessmann says. Their Vitotronic Control which is generally optional even allows for safe low temperature operation.

Greentech.ie will provide you guidance to achieve high energy efficiencies in Viesssmann and other Condensing Boilers.

Condensing Boilers they say are the most efficient fuel burning
Central Heating System boilers in a building.
The efficiencies typically may run as high as 98 % according
to claims by the manufacturers.
The same items on test beds of units of certifications according
to SEDBUK of UK on the other hand would show this to be around 95 % at best.
In real life this can be typically about 82 % – 89% and would be about 90% at best.
Bear in mind that all these efficiencies are worked out when High Heating Value (HHV)
fuels are used and conditions are near ideal.

Conventional Boilers have efficiencies ranging from 70 % to 80% and no more.
So still one could say the condensing boiler is more energy efficient.
But it boils down to whether it is a worthwhile investment when you want
to replace your old conventional boiler or buy a new boiler for your new house.

To really understand how this disparity occur one must understand the working of a condensing boiler.

Working of a Condensing Boiler

The condensing boiler too is a fuel burning device which utilizes the intrinsic energy of the burning fuel (generally some form of fossil fuels) to elevate the temperature of water circulating in a heat exchanger up to boiling condition or superheat.
Typically this much is common for both types of condensers.
In both cases the flue gases are exhausted.
The condensing boiler deviates here in that, the steam or vaporized water in the flue is made to give up its imbibed thermal energy (called Latent Heat of vaporization) back to the system by means of a secondary heat exchanger.
This waste heat recovery is what makes the condensing boiler hover around 98% efficiency (on test bed that is).

How to overcome the low efficiency?

In order to even achieve this level of performance, there are several conditions to be maintained.
For e.g.

• The return water temperature from the system has to be low as possible for the maximum water vapour to condense releasing the latent heat and elevating the total heat generated.
  A flow temperature of 50 ⁰ C would be good temperature for this.
  • On the other hand when the return water temperature is that low the hot water takes quite a longer time to heat up to the useful temperature which is  about 84 ⁰C.
    (The longer heat up duration is not an acceptable situation to the ultimate user).
  • All condensing boilers are delivered from the factory with a default setting which is high and set that way in order to provide the system the widest practical in /out temperature difference.
    However this disregards the need for the high fuel efficiency which is the prime the requirement in preferring the condensing boiler (over the conventional boiler) in the first place.
  • Combining the domestic hot water and space heating systems to the same boiler would improve the seasonal energy efficiency.
    This arrangement however might need a duel temperature valve having settings of 63 ⁰C (fully condensing condition) and 84 ⁰C (partial or zero condensing).

In any event the condensing boiler still maintains higher fuel efficiency than the conventional boiler though this would not make you eligible for any grants and high green BER ratings.

Greentech.ie will provide you guidance to achieve high energy efficiencies in Condensing Boilers.