Condensing boiler · New equipmentWolf FGB – K 35

Wolf FGB – K 35

VAT includedIn stock

The Wolf FGB-K 35 is the highest capacity variant in this selection: 31.1 kW of useful heating at 80/60 °C, 34.9 kW at 50/30 °C, and 16.3 l/min of specific domestic hot water flow at ΔT 30 K. It maintains a body size of 650 x 408 x 310 mm and provides instantaneous sanitary production. Equipment without installation; confirm the accessories for this configuration. VAT and mainland shipping included.

Heating power (80/60 °C): 31.1 kW
Specific flow rate for domestic hot water (ΔT 30 K): 16.3 l/min
Body (height x width x depth): 650 x 408 x 310 mm

Condensing boiler

The model, at a glance

Wolf FGB-K 35: 31.1 kW output at 80/60 °C, instantaneous domestic hot water with 16.3 l/min specific at ΔT 30 K. Dimensions, comparison, and PDF in Spanish.

Heating power (80/60 °C): 31.1 kW
Specific flow rate for domestic hot water (ΔT 30 K): 16.3 l/min
Body (height x width x depth): 650 x 408 x 310 mm

Read the full description and what it includes.

The useful heating range is from 6.7 to 31.1 kW at 80/60 °C. Compared to the FGB-K 24 and 28, it has a higher maximum, but the minimum modulating output also increases from 4.8 to 6.7 kW. Therefore, it is worth reviewing the demand during mid-seasons and with few emitters open, not just the peak cold.

Its 34.0 kW output in domestic hot water and 16.3 l/min specific at ΔT 30 K provide more sanitary capacity than the other two variants. This normalized figure does not guarantee two simultaneous showers: a combined consumption close to the limit leaves little margin for colder incoming water or pressure losses.

The compact body weighs 28 kg and features sanitary connections G 1/2, heating connections G 3/4, and an 8-liter heating expansion vessel. The basic digital control is part of the equipment; the WOLF LINK PRO remote control and the BM-2 regulation are accessories that must be selected separately. The dimensions of the body do not include all elements or installation clearances.

What is included in the purchase?

Equipment without installation. Please confirm the accessories for this configuration.

Price including VAT and shipping to mainland Spain. Installation, adaptations, and commissioning are valued separately.

Consult the manufacturer's PDFs ↓

Guide

What to check before installing this boiler

The choice of equipment does not replace the inspection of the installation by a qualified professional.

Confirm the model and commercial reference, the type of gas, and the supply configuration in the manufacturer's documentation.
Ask a qualified installer to assess the heating and domestic hot water demand; compare measured flow rates at the same temperature difference.
Check dimensions, connections, flue gas evacuation, condensate drainage, and controls compatible with the existing installation.
Confirm the included accessories and the delivery time before scheduling the installation. The online purchase of the equipment does not include installation or commissioning.

Technical data

Technical data of Wolf FGB – K 35 boiler

Brand: Wolf
Model: Wolf FGB – K 35
Status: New
Supply scope: Equipment without installation; please confirm the accessories for this configuration.
Shipping: Included in mainland Spain. Please confirm the deadline.

Specifications and dimensions of the model

Compare each magnitude under its testing conditions: heating, domestic hot water, efficiency, and dimensions.

Maximum useful power (80/60 °C): 31.1 kW
Heating
Maximum useful power (50/30 °C): 34.9 kW
Heating
Minimum power (80/60 °C): 6.7 kW
Heating
Minimum useful power (50/30 °C): 7.5 kW
Heating
Maximum heating pressure: 3 bar
Heating
Heating expansion vessel: 8 l
Heating
Production of domestic hot water: Instantaneous, without integrated domestic hot water accumulator
Hot water
Maximum useful power in domestic hot water: 34 kW
Hot water
Specific flow rate of domestic hot water (ΔT 30 °C): 16.3 l/min
Hot water
Adjustable domestic hot water temperature: 30–65 °C
Hot water
Maximum domestic hot water pressure: 10 bar
Hot water
Body dimensions (height x width x depth): 650 × 408 × 310 mm
Dimensions and connections
Weight: 28 kg
Dimensions and connections
Heating connections: G 3/4 inches
Dimensions and connections
Domestic hot water connections: G 1/2 inch
Dimensions and connections
Gas connection: G 1/2 inch
Dimensions and connections
Concentric flue connection: 60/100 mm
Dimensions and connections
Electrical supply: 230 V / 50 Hz
Dimensions and connections
NOx emissions class: 6
Efficiency and consumption
Standby power consumption: 2 W
Efficiency and consumption
Maximum electrical consumption: 114 W
Efficiency and consumption
Degree of protection: IPX4D
Efficiency and consumption
Maximum flow temperature (approx.): 85 °C
Heating
Minimum flow pressure for domestic hot water (EN 15502-2-2): 0.3 bar
Hot water

Manufacturer's sources

PDF and documentation of the model

Original documents, unmodified. Refer to the installation plan and the conditions of each data point before selecting the equipment.

WOLF technical catalog 2026 · FGB-K 35PDF · 358 pages · Wolf View original on the manufacturer's website ↗

The gallery sheets are summaries of Uniclima based on these documents. The external volume diagram does not represent connections, accessories, or service distances.

Frequently Asked Questions

Frequently asked questions: condensing boilers

Does the Wolf FGB-K 35 work for a house of 180 m²?

It can cover a heating demand that does not exceed 31.1 kW useful at 80/60 °C. As a calculation example, 180 m² with assumed losses of 80 W/m² would require 14.4 kW. This is not a surface recommended by Wolf: climate, insulation, ventilation, and emitters change the actual load. It is also necessary to check its minimum of 6.7 kW, as a lower demand may cause on and off cycling.

Can the FGB-K 35 supply two showers at the same time?

Two showers of 8 l/min would add up to 16 l/min at a temperature rise of 30 °C, very close to the 16.3 l/min specific declared. The margin is small and does not guarantee simultaneous service. The example assumes water that goes from 10 to 40 °C. The specific flow rate is a standardized measure, not a measurement of mixed water at the tap or an adjustment of the limiter. The available pressure, the pipes, the setpoint, and colder incoming water can modify the result.

Does the FGB-K 35 have a domestic hot water accumulator?

It does not include a reserve sanitary tank: the FGB-K 35 prepares domestic hot water instantaneously. The 8-liter expansion vessel belongs to the heating system and does not store water for showers. The EcoWOLF function with BM-2 regulation is a micro-accumulation option of the family, not a volumetric tank; the control and accessories must be checked separately.

What space do I need to install the Wolf FGB-K 35?

The body measures 650 mm in height, 408 mm in width, and 310 mm in depth, with a weight of 28 kg. It is not enough to have a space with those dimensions: the plan includes bottom connections and the flue outlet, and specifies an optional flange of 30 mm. Additionally, the separations and maintenance access required by the installation instructions must be reserved. Check the plan before reusing the cabinet from another boiler.

What is the difference between the FGB-K 24 and 28?

The FGB-K 35 declares 31.1 kW of useful heating at 80/60 °C, 34.9 kW at 50/30 °C, and D=16.3 l/min. The FGB-K 24 and 28 declare, respectively, 19.4/20.7 kW and D=10.55 l/min, and 24.4/27.3 kW and D=13.4 l/min in comparable magnitudes. The choice must confront the expected thermal load and domestic hot water; more power does not automatically equate to better adaptation if the minimum modulating output is above the low demand. The minimum power at 80/60 °C is 6.7 kW in this 35; in the 24 and 28 it is 4.8 kW and in the 35, 6.7 kW.

Can the FGB-K 35 be used with radiators and underfloor heating?

The FGB-K family supports schemes with a direct circuit and a mixed circuit. In the 35, the heating values are 31.1 kW useful at 80/60 °C and 34.9 kW at 50/30 °C; these are not the same working conditions. To combine radiators with underfloor heating, it is necessary to design the temperature control, mixing, and components of each circuit. The compatibility of the scheme does not imply that those controls or accessories are included with the boiler.

Does the price include installation and shipping?

Includes VAT and shipping to mainland Spain. Installation and adaptations are valued separately. Check the contents of the supply before purchasing.