High Efficiency Condensing Boilers

A wide range of high output floor standing condensing boilers, sized from 120 to 250 kW. Suitable for medium or large residential and commercial installations. Perfect for new build projects or renovations that require a high and dependable heat output. Our stainless steel heat exchanger ensures high efficiency and reliability, with a compact size and small footprint.


NOx class:

108 %
Thermal efficiency up to:

Modulation ratio up to:


heat input (net) G20 kW 11.2 - 115.5
heat input (net) G31 kW 28.9 - 115.5
heat output at 80/60°C G20 kW 10.8 - 112.8
heat output at 80/60°C G31 kW 27.9 - 112.8
heat output at 50/30°C G20 kW 12 - 124
heat output at 50/30°C G31 kW 30.5 - 122


heating efficiency 80/60°C % 96.5 - 97.8
heating efficiency 50/30°C % 107.4 - 107.5
useful efficiency at 30% (return 30°C) % 108.7
seasonal efficiency % 93


water content l 51
gas categories I2H, I2E, I2E(S), I2E(R), I2ELL, I2HS, I2N, I2EK, I3P, II2E3P, II2E(S)3P, II2E(R)3P, II2EK3P, II2H3P, II2L3P, II2E+3P, IIEsi3P, II2Er3P
gas types G20 - G25 - G25.1 - G25.3 - G31
chimney type(s) B23 - B23P - C43 - C53 - C63 - C83
CO emission mg/kWh 64.5
gas flow rate (G20) m3/h 1.1 - 10.7
gas flow rate (G31) m3/h 1.2 - 4.5
NOx class 6


boiler width (A) mm 648
boiler height (B) mm 1524
boiler depth (C) mm 631
empty weight kg 185


air inlet mm 125
gas connection in 3/4
water outlet in 2
water inlet in 2
chimney connection mm 130
condensate drain mm 25
Nesta N 120


At the core of all NESTA boilers is our stainless steel Fire Tube heat exchanger. The use of high-grade stainless steel alloys ensures product durability, reliability, and higher resistance to corrosion and oxidation.

Our unique Fire Tube design of Nesta heat exchangers is a market proven technology, manufactured and distributed worldwide for many years.
Our commitment to improvement and advancement in design has produced one of the most efficient boilers in its class.


Fire Tube heat exchanger

One of the major advantages of Nesta Fire Tube heat exchanger is the self-cleaning feature.  The unique design and orientation of the heat exchanger allows the condensate to run down the inside of the heat exchanger tubes and cleans any possible traces of combustion residue. This function allows the boiler to maintain maximum efficiency throughout the lifespan, leading to reduced running costs and maintenance for the end user.

Key Features & Benefits

  • Stainless steel heat exchanger
  • Self-cleaning flue ways
  • Internal circuit piping in welded stainless steel
  • Low pressure drop
  • Compact dimensions
  • Reduced maintenance
  • Can be installed in cascade up to 6 boilers
  • Low NOx

Evolved ECU flexibility

Intuitive for both the user and the engineer, complete with weather compensation functionality. The integrated AIC Electronic Control Unit (ECU) can manage up to 3 direct or mixed circuits and one circuit for DHW production via an external storage cylinder with anti-legionella function when installed with additional control accessories. It can also manage up to 6 boilers in cascade and has connectivity for regulation and remote control.

Internal control unit

The internal control unit of the Nesta boilers allows for management of cascades up to 6 boilers in a series of direct and mixed circuits and additional DHW circuit, with boiler management and alarm. The Nesta is also equipped for remote management via ethernet network or GSM router.

Ease of installation and maintenance

The Nesta boiler has a small footprint - only 0.5 m2, which promotes easy installation in plantrooms where space is at a premium. All models in the Nesta range are sized to allow easy passage through a 70 cm wide doorway, ensuring easy maneuverability without disruption to the building. Thanks to the boiler geometry, the self-cleaning flue ways of the Fire Tube exchanger simplifies routine maintenance operations and related costs, offering maximum efficiency over the entire life span the boiler.


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