Central condensing boiler: replacing it in a condominium

Replacing the central boiler with a condensing generator is one of the measures with the best cost-to-saving ratio in a condominium. A condensing boiler recovers the latent heat contained in the flue gases, reaching higher efficiency than old traditional generators and cutting the gas consumption of the shared thermal plant. For the condominium it means lower bills and fewer emissions, with a measure focused on the plant and not on individual units.

Why condensing is now the standard

European ecodesign rules for products have in practice made condensing generators the standard for new installations: when an old boiler is replaced, the technical choice almost always falls on a condensing appliance, except in particular cases tied to the plant configuration or to collective flues. Maintenance and energy efficiency checks of thermal systems are governed by Presidential Decree 74/2013 and by the framework of Legislative Decree 192/2005, which set minimum efficiencies and periodic inspection obligations.

Extraordinary maintenance or innovation

How the works are classified affects the majorities. If the old boiler is broken or at the end of its life and must be replaced to guarantee the service, it is extraordinary maintenance to preserve the common plant, which the meeting resolves by ordinary majorities. If instead the replacement is conceived as an energy efficiency improvement, with a performance jump over the pre-existing generator, it can fall among the innovations for containing energy consumption under Article 1120, second paragraph, of the Italian Civil Code, which enjoys the reduced quorum of a majority of those attending representing at least half the value of the building.

The allocation of heating costs

The cost of the works on the common boiler is split among the owners served by the central plant. For systems with heat metering, the split of heating costs follows the technical standard UNI 10200, which distinguishes two components:

• A share for voluntary consumption, measured by heat cost allocators or thermostatic valves, which rewards those who consume less.
• A share for involuntary consumption and engaged power, split according to the thousandths of demand, which covers the losses of the common network.
• The extraordinary maintenance costs of the plant, such as replacing the boiler, split according to the thousandths of ownership or the criteria resolved.

It is important not to confuse the split of fuel, governed by UNI 10200, with that of the extraordinary works on the plant, which follows the general rules for allocating common parts.

Documents and obligations after replacement

Once the works are finished, the system must be updated with the new thermal plant logbook and with the recording of energy efficiency checks. The condominium must keep the technical documentation of the new generator, the declarations of conformity and the inspection reports, which may be requested during checks. If the works access energy efficiency incentives, the specific documentation required must be respected, including any technical communications tied to the performance improvement.

A measure to fit into a wider plan

A condensing boiler performs best when the distribution system runs at moderate temperatures and the envelope is well insulated: for this reason it is best coordinated with other measures on the building, such as roof insulation or replacement of common windows. A preliminary energy audit helps understand whether the boiler alone is enough or whether a package of measures is needed.

To manage quotes, resolutions, the fuel split under UNI 10200 and maintenance deadlines, management software such as AmministraPro keeps accounting, logbooks and owner communications together. The features are described on the /funzioni page and the plans with their costs on the /prezzi page.