14/01/2021 – The deadline climate control referring to the heating and domestic hot water (DHW) production system, indicates a system, intended for the single residential unit, which can be managed in full autonomy as regards the operating times, the set temperature and consequently the consumptions that derive from it.
The autonomous heating system has gradually established itself since the end of the 1970s. It works by means of a heat generator, better known by the name boiler. There are different types of boilers, but that of mural type with natural gas operation it is among the most used.
The first autonomous boilers to appear on the market were the type B11 boilers, better known with the only letter “B”; are generators a open combustion chamber, with intake of combustion air from the installation room and flue gas discharge directly outside or into a special collective chimney, without using a fan.
The flue gas exhaust system of type B11 boilers was not entirely safe, in fact, these boilers have been the cause of various domestic accidents in the past. For this reason, the legislation has introduced the obligation to install a control device for the evacuation of fumes. The boilers of type B11 have thus become of type B11BS.
Subsequently the producers have conceived and realized safer solutions and at the same time more efficient in terms of energy: le type C boilers. They are chamber generators of sealed combustion with respect to the installation room and, therefore, with intake of combustion air and exhaust of fumes directly outside or in special collective chimneys.
The latest evolution of type C boilers is the condensing boiler.
Photo: wall-mounted condensing boiler ROTEX GW© DAIKIN Heating Systems
Replacing an old boiler: facilitations and regulatory references
Today, replacing an old boiler, which pollutes and consumes, should be a dutiful gesture towards the environment. Gesture that would also be convenient thanks to the tax breaks of theecobonus he was born in super bonus.
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From 3 August 2013, with the Law 90/2013, all the smoke discharges combustion must take place above the roof, in particular 1 meter above the ridge (UNI 7129:2015) except for exceptions.
Furthermore, from 26 September 2015 the Ecodesign Directive, or the European ERP directive (Energy Related Products, 2009/125 / EC). On the basis of this legislation, traditional open chamber boilers, type B, have been discontinued and their installation is no longer permitted. The legislation also requires that in case of new installation O replacement, the boiler, no longer working, will be replaced with one with a high energy efficiency, that is condensing.
Photo: wall-mounted condensing boiler in tempered glass LOGAMAX PLUS GB172I ©BUDERUS
Condensing boiler and flue gas discharge
The evacuation of the combustion products takes place through special ducts: fireplaces O flues connected to the boiler.
In general, it defines itself camino the duct that disposes of the fumes coming from a single system, i.e. from a single appliance (single house), or more similar appliances placed on the same floor (two-family, terraced, etc.). Instead, it defines itself flue the duct that disposes of the fumes coming from several autonomous appliances located on several floors, a typical case of an apartment building.
If in the case of a single dwelling, replacing the boiler with a condenser is “easy”, it is not always so in the case of a condominium.
The condensing boiler poses an important question to consider, that of low temperature flue gas discharge to which is added the training of condensation water with acid pH, but which we will deal with in another focus.
A condensing boiler is able to cool the exhaust fumes faster and more than a traditional type C or B.
The fumes, when produced, are hot, in a gaseous state and rich in water vapor. The latter, due to the cooling process, is transformed into water with an acid pH (condensation). During the transition, part of the heat of the fumes is released in the form of energy used in turn by the boiler itself. The heat transferred to the boiler determines a higher efficiency and the fumes transformed into water cause less polluting emissions into the environment.
The fumes are expelled by means of a fan fitted to the boiler itself, inside the evacuation duct, as required by law. Along the way, the exhaust fumes will still continue to condense, producing acidic water. For this reason the duct must be suitable for wet operation, made with specific materials and characteristics.
Photo: condensing boiler CLAS PREMIUM EVO SYSTEM©ARISTON THERMO
Replace an old boiler, compatible and incompatible cases
Compared to the existing one, the following cases may arise:
– masonry ducts are not compatible with condensing boilers because acidity corrodes the masonry;
– branched collective flues (CCR), those used for type B boilers, are not compatible with condensing boilers;
– collective or combined collective flues, the one used for type C boilers, are compatible only in the cases specified by the UNI 7129: 2015 standard.
In these cases, the legislation specifies that: “in the case of existing collective pipes, it is possible to replace a conventional type C appliance with a condensing one only in the presence of dimensional verification according to UNI EN 13384-2, UNI 10641 or other method of proven effectiveness; which provides for the possibility of replacing all connected appliances with condensing appliances (even at different times) and guarantees functionality in all conditions. Furthermore, before the dimensional verification, the other essential characteristics must be checked to ensure compatibility between the collective barrel and the new devices as well as the correct wet operation of the collective barrel. “
Photo: Built-in condensing boiler START IN CONDENSATION© RIELLO
Condensing boiler, exceptions to replacement
As mentioned above, by law the flue gas discharge must take place above the roof, through evacuation ducts. Sometimes, however, pre-existing chimneys or flues are completely incompatible with the condensing boiler; there Law 90/2013 allows wall drainage, notwithstanding the obligation of the roof drain, for some specific cases:
a) replacement of a boiler, of any type, which already it was unloading on the wall (before August 31, 2013); this condition must be proved;
b) replacement an open chamber boiler (type B) which discharged into a CCR collective branched condominium flue;
c) new installation in historic buildings or buildings subject to protection regulations;
d) technical impossibility to go to the roof with the smoke outlet, certified by a qualified professional
Furthermore, the Legislative Decree 102/2014 provides exceptions also for:
e) installation of appliances condensing, in the context of renovations of existing individual heating systems, sites in a condominium, if they are not already present: chimneys, flues or systems for the evacuation of combustion products with an outlet above the roof of the building, functional and suitable or in any case adaptable to the application of the aforementioned generators;
f) installation of one or more compact hybrid generators, consisting of at least a gas condensing boiler and a heat pump, with specific product certification.
Finally, it should be noted that the derogation is subordinate the minimum performance requirements prescribed by art. 4, paragraph 6, letter a), of D.P.R. 59/2009, according to which the new boiler must be “ecological”, with efficient yields and low polluting emissions. It will not be possible to install one similar to the existing one.
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