Pellet boilers
Opera 28
Hevo 21
Hevo 18
Hevo 14
How a pellet boiler works
A pellet boiler heats the water circulating in the heating system: radiators, fan coils or underfloor heating. It is a direct replacement for a gas or oil boiler, not an appliance that heats a single room.
The pellets reach the burn pot from a hopper, a heating element ignites them and a control unit regulates combustion according to the temperature the system requires. The flue gases are discharged through a dedicated flue.
What sets it apart from a pellet stove or a hydro pellet stove is heat output and operating logic: a boiler is sized for the entire heat demand of the building and works by modulating, not by switching on and off.
Floor-standing or wall-mounted
This is the first decision to make, and it depends on the space available more than on performance.
Floor-standing. The classic configuration: the boiler stands on the floor in a plant room, with maintenance clearances around it. Opera 28 weighs 320 kg and measures 1146 × 1240 × 700 mm. In exchange for its footprint, it offers a 90 kg internal hopper, up to 56 hours of burn time and instant domestic hot water with no storage tank.
Wall-mounted. HEVO weighs 105 kg and measures 580 × 910 × 463 mm: it fixes to the wall in the footprint of a wall-mounted gas boiler, leaving the floor free. For domestic hot water it must be paired with a hot water cylinder.
The choice comes down to two questions: do you have a plant room with floor space, and do you need instant hot water? If the answer to both is yes, floor-standing is the natural route. If space is lacking, the wall-mounted model makes possible a project that otherwise could not go ahead.
What heat output you need
A boiler is sized according to the building’s heat demand, not by guesswork. The calculation takes into account floor area, volume, insulation, orientation, climate zone and type of heat emitters. It is done by the designer or installer, and on a central heating system it is a step not worth skipping.
As a rough guide: Opera 28 covers up to 230 m², while the three HEVO models cover from 320 to 490 m³ of heatable volume.
Oversizing is not playing it safe. An overpowered boiler almost always runs at minimum, with less efficient combustion, more residue and higher consumption than a correctly sized machine.
No loading pellets by hand
It’s the objection that holds back people switching from gas, and on a boiler it has no reason to exist.
All our models connect to an external silo with pneumatic feed: the pellets are drawn in automatically as they are needed. With a silo sized for the season, supply comes down to one delivery a year — just like a heating oil tank.
The internal hopper remains as a reserve: 90 kg on Opera, 23 kg on HEVO.
What you need to install it
A flue compliant with UNI 10683, with a diameter suited to the model. It is not always possible to reuse the flue of a gas boiler: this must be checked by the technician.
Space for the pellets, in the plant room or next to it. With pneumatic suction, the silo can be up to 20 metres away.
A connection to the existing system. In most replacements the distribution system is left untouched: only the heat generator is replaced.
A hot water cylinder, if the chosen model does not produce domestic hot water directly.
Frequently asked questions
Can a pellet boiler replace a gas boiler?
Yes. It connects to the same distribution system and supplies the same heat emitters. The requirements are a suitable flue and space for the pellets. For domestic hot water, check whether the model produces it directly or requires a hot water cylinder.
What is the difference between a boiler and a hydro pellet stove?
Both heat the water in the system, but a hydro pellet stove sits in the living space and also gives off radiant heat, while a boiler sits in a plant room and is sized for the entire heat demand of the building, with higher heat outputs. See our hydro pellet stoves.
How many pellets does it use in a season?
It depends on the building, the climate zone and the hours of operation. The hourly consumption of our models ranges from 0.9 to 5.6 kg/h depending on heat output and operating mode. Correct sizing and good insulation make more difference than the machine itself.
Do I need a storage tank or buffer tank?
Not always. It depends on the type of system, the heat emitters and whether there are other heat sources. This is assessed by the designer at the sizing stage.
How much maintenance does it require?
Regular cleaning of the burn pot and ash drawer, at intervals based on the hours of operation, and annual servicing by a qualified technician — mandatory for the warranty and to access incentives.
Can I install it in a flat?
It depends on the building’s regulations and on having a dedicated flue and space for the pellets. The wall-mounted version reduces the space problem, but the flue and pellet storage still need to be addressed.