Types and working of condensing boilers
The continuously increasing cost of fuel has led the industry to create products that are more efficient and less polluting.
Thus were born the boilers "condensing". This name derives from the fact that in the boiler there is a particular exchanger that captures the heat of the exhaust fumes (which would otherwise be lost along with the flue gas), up to to condense the exhaust gases to be able to capture that heat (latent heat) that is trapped in the water vapor.
THE RESTORATION OF ENERGY IN 3 STEPS
1 - Reduce losses recovering some of the heat that would otherwise be lost with the flue gas.
2 - Improving the efficiency Running a condensing boiler to a lower temperature, it increases productivity. Then use radiators or fan coil well sized. Or opt for underfloor heating (it works at very low temperatures) maybe combined with solar panels.
3 - Optimize the management Use temperatures are not too different from those outside (the lowest temperature drop also benefits to health, as well as reducing losses) and air-conditioned only the environments in which you are staying. A crude but effective solution: the living area and sleeping area. Use thermostats or thermostatic valves.
Description of condensing boilers
The use of condensing boilers ensures the best energy saving currently achievable (in the case of conventional source: natural gas or LPG).
Condensing boilers usually make use of special burners microflame that give a higher efficiency and lower emissions.
To promote an almost perfect combustion, the amount of gas and air are always placed in a proportionally adjusts via a fan and a valve particular.
Optimizes the efficiency of condensing boilers is the use of an external temperature sensor that detects the external conditions, decreases or increases with the temperature. This also results in less dispersion and lower convection (which carry warm air toward the ceiling).
Often condensing boilers you hear with a fear, thinking about the higher cost than regular boilers, but without thinking about the advantages of condensation. Not only less pollution but also a significant energy savings, which can be up to 30% per annum.
But how do condensing boilers? What a condensing boiler is more than in a normal, and recover the heat of combustion fumes. The cooling of these fumes, which generates condensation, originates the name for this type of boiler. In condensing boiler, the combustion products, before being expelled to the outside, have to pass through a special heat exchanger within which the water vapor condenses, giving up part of the latent heat of condensation of the water circuit.
The condensing boiler, for the same energy supplied, consumes less fuel than a traditional type.
Usually the fumes of a traditional boiler are expelled at temperatures around 110 ° C. The temperature of the fumes expelled by a condensing boiler, instead, part of about 40 ° and not more than 55 ° C: it is evident that the recovery of useful heat is remarkable. And 'this recovered heat which reduces fuel requirements that the boiler has to spend to heat the water in the system.
From here we can understand why, with the regular formula for the calculation of boiler efficiency, yields are higher than those condensing at 100% (can amaze the yield quoted more than 100%).
It has been estimated that the investment in the installation of a condensing boiler can be recovered within 7 years. Calculating the tax deduction of 55% return on investment you have in just 3 years (subject to the need for additional work for the adaptation of an existing system). E 'is therefore evident that the switch from traditional heating to that condensation is extremely beneficial.
Condensing boilers are currently the ones with the most advanced technology.
To optimize the performance of a system based on condensing boiler, there should be ample and efficient radiant surfaces, so you can keep the temperature of the water (fluid). The ideal temperature for the system design, supply and return, are equal to 40/30 ° C. In the case of a plant at high temperatures with traditional radiators, the design temperature will be higher, roughly equal to 75/60 ° C. In these conditions the fumes may not transfer heat to the fluid itself. It is for this reason that the greatest benefit in terms of savings can be found on underfloor heating systems, where the working temperatures of the system are low, on average between 40/30 ° C.
A condensing boiler, in general, is a concentrate of high technology: in addition to the heat exchanger constructed with special materials capable of withstanding the chemical aggression of the condensate, with optimized cross-sections and very extensive exchange surfaces to recover the greater amount of heat, There are other technological solutions that contribute to improving their effectiveness. Among the most useful electronic control of the combustion and the use of a burner technologically advanced (constructed with special materials, premixed, modulated and with a careful design of the constructive geometry of the combustion chamber). These devices by optimizing combustion, allow you to reduce the level of pollutants emitted.
The condensed products of combustion are mainly discharged into the sewer. The current rules provide compliance with the law on discharges (related to their degree of acidity and neutralization by mixing with domestic sewage or a neutralizer installation).
The condensates produced by a condenser have a strong degree of acidity. Forced choice then, for designers and installers, the use of materials capable of resisting corrosion of the condensates. (Plastic materials such as PVC, ABS and HPE, able to resist corrosion for the entire life of the plant).
Replacing the old boiler with a condensing
Now let's see the differences between new and existing plant facility, where you want to replace your old boiler with a condensing.
For systems installed in new buildings, especially if they have already been configured to install condensation generators, you will get the best results. These plants, will have the additional costs compared to conventional, but will be amortized during use.
In existing plants, it is necessary to assess the feasibility of the operation. They must also be taken some measures to ensure the best performance of the system and ensure the savings to the user.
The flue systems interlocked with condensing boilers and related systems are wet. Therefore, they must have suitable characteristics.
The flues may operate under pressure or depression. In most cases, the flues of the condensing boilers operate under pressure and wet.
To adapt the system, you will have to check the compatibility of the fireplace to receive the condensed combustion products. Often fireplaces / chimneys exist are not compatible for operation wet. The ducting system, in most cases, it may be the safest and least expensive for the adjustment.
When the replacement is done in independent living unit, such as a house, there will be no particular difficulties nell'intubamento exhaust fumes. Which does not happen when you have to replace the generator in the apartment of a multi-storey building. Solutions exist, but may require more intensive technical and economic. Often in multi-storey buildings with old plants, boilers are installed in open chamber connected to collective branched rods. It will be necessary to carefully evaluate which solution adopted: for example, the realization of a new flue outside the building, or the discharge wall (when allowed).
In an existing installation, you will have to prepare the system for condensate discharge and check the compatibility of the materials of domestic sewage to receive condensates. If the material with which they were made not prove suitable, you will be able to compensate for installing a condensate neutralizer before entering the exhaust system pet. Attention also to the sewer, which generally are however suitable to receive the condensates.
You must also include a temperature control more evolved than the traditional thermostat on / off. You will have to install an external probe and a room thermostat, programmable on two levels of temperature and different needs daily / weekly. These devices allow you to optimize the efficiency of the system.
Clean the system from scale, sludge or scale deposits that can form in years of operation, it is essential in order to maintain the performance of the boiler.
Install a generator condensing in an existing system, it implies costs for its adaptation. But with a correct analysis of the adjustment operations, small steps and proper calibration, you will still have the benefits very close to that of a system created to condensation and still more than a traditional system.
Another viable alternative is otherwise the use of heat pump systems.
22/11/2009
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Translated via software
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Source:
Italian version of CercaGeometra.it