Wolf FGB – K 28 boiler
Condensing boiler · New equipmentWolf FGB – K 28
New boiler Wolf Condensing boilers

Wolf FGB – K 28 boiler

Heating and hot water for everyday use, combined in a gas boiler.

Gas
Natural gas Convertible to propane
Wi-Fi
Optional WOLF Link Pro
Heating
24.4 kW 80/60 °C
Domestic hot water flow rate
13.4 l/min ΔT 30 K
Gas and Wi-Fi: compatibility and accessories

Gas and conversion: Natural gas G20 supply; adaptation to propane G31 with the kit and adjustments indicated by the manufacturer. Compatibility with butane G30 is not offered without explicit documentation for this version. The conversion and commissioning are the responsibility of a qualified professional; they are not included in the purchase. Source 1 ↗

Wi-Fi and supply: FGB-K supports WOLF Link Pro (ISM7e), external LAN/WLAN accessory. WOLF Link Home is not the suitable module for this family. Regulation and commissioning must be adjusted to the installation. Source 1 ↗

Description

Wolf combines home heating and hot water for taps and showers. When choosing it, both water usage and heating needs are important: a home with multiple showers running at the same time requires a different assessment.

Domestic hot water is prepared when you turn on the tap, without an integrated storage tank. It is important to check how many water points you will use at the same time and the available space to replace the boiler.

Guide for this modelDoes your boiler show an error?Wolf FGB – K 28See codes
Guide

What to check before installing this boiler

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

  1. Confirm the model and commercial reference, the type of gas, and the supply configuration in the manufacturer's documentation.
  2. Ask a qualified installer to assess the heating and domestic hot water demand; compare measured flow rates at the same temperature difference.
  3. Check dimensions, connections, flue gas evacuation, condensate drainage, and controls compatible with the existing installation.
  4. 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 28 boiler

Brand
Wolf
Model
Wolf FGB – K 28 boiler
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)
24.4 kW
Heating
Maximum useful power (50/30 °C)
27.3 kW
Heating
Minimum power (80/60 °C)
4.8 kW
Heating
Minimum useful power (50/30 °C)
5.3 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
27.3 kW
Hot water
Specific flow rate of domestic hot water (ΔT 30 °C)
13.4 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
27 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
102 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)
0.2 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.

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 28 work for a 140 m² house?
It can cover a heating demand that does not exceed 24.4 kW useful at 80/60 °C. As a calculation example, 140 m² with assumed losses of 80 W/m² would require 11.2 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 4.8 kW, as a lower demand may cause on and off cycling.
Can the FGB-K 28 supply two showers at the same time?
Two showers of 7 l/min would add up to 14 l/min; at a temperature difference of 30 °C, they would exceed their specific 13.4 l/min. To compare two open points, it is necessary to know their combined consumption and the inlet temperature. 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 inlet water can modify the result.
Does the FGB-K 28 have a domestic hot water accumulator?
It does not include a reserve sanitary tank: the FGB-K 28 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 28?
The body measures 650 mm in height, 408 mm in width, and 310 mm in depth, with a weight of 27 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 from the FGB-K 24 and 35?
The FGB-K 28 declares 24.4 kW of useful heating at 80/60 °C, 27.3 kW at 50/30 °C, and a flow rate of 13.4 l/min. The FGB-K 24 and 35 declare, respectively, 19.4/20.7 kW and a flow rate of 10.55 l/min, and 31.1/34.9 kW and a flow rate of 16.3 l/min in comparable magnitudes. The choice must confront the expected thermal load and domestic hot water; the surface area alone does not justify increasing or decreasing power. The minimum power at 80/60 °C is 4.8 kW in this model 28; in models 24 and 28 it is 4.8 kW, and in model 35, it is 6.7 kW.
Can the FGB-K 28 be used with radiators and underfloor heating?
The FGB-K family supports schemes with a direct circuit and a mixed circuit. In model 28, the heating values are 24.4 kW useful at 80/60 °C and 27.3 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.
Shipping to the mainland included
New equipment
Separate installation
Informed purchase
Wolf FGB – K 28 boiler