Viessmann Vitodens 100-W 25kW B1HF System Boiler | 7988418

Description

The Viessmann Vitodens 100-W is the flagship wall-mounted gas condensing boiler in the Vitodens range, pairing the MatriX-Plus gas burner with intelligent Lambda Pro combustion control and the corrosion-resistant Inox-Radial stainless steel heat exchanger.

This 25kW system boiler variant heats a separate hot water cylinder, offering a well-balanced output for medium-sized homes with moderate heating and hot water demand.

25kW

System output

94%

Seasonal efficiency (ηS)

46 dB(A)

Sound level

Class A

Energy efficiency

360mm

Depth

WiFi

Built-in connectivity

🛈

Please Note: This boiler must be connected using the Viessmann 60/100mm concentric flue system, tested and CE-designated as one structural unit with the boiler in accordance with DVGW-VP 113. Only this flue system may be used, with maximum flue lengths varying by model — check the installation manual for the exact figure.

ℹ

Good to Know: This boiler is approved for a hydrogen admixture of up to 20% by volume and can be configured for LPG entirely from the control unit — no separate conversion kit is required.

MatriX-Plus burner with Lambda Pro

Delivers extremely clean combustion and quiet operation, with automatic combustion control across the full modulation range.

Low sound power output

Rated at just 46 dB(A) at full output, keeping the boiler unobtrusive in living spaces.

Inox-Radial stainless steel heat exchanger

Provides high operational reliability and a long service life on a compact footprint.

Variable speed high efficiency circulation pump

Cuts pump power consumption by up to 70% compared with a fixed-speed equivalent.

Integral WiFi with local app access

Supports the ViCare app for remote control, plus local commissioning access without an active internet connection.

Touchscreen control unit

Easy day-to-day operation via a backlit LCD touchscreen display.

Specification

Performance

Boiler type

Gas condensing system boiler (Type B1HF)

Rated heat output (50/30°C)

3.2 – 25.0 kW

Rated heat output (80/60°C)

2.9 – 23.0 kW

Continuous cylinder heating output

2.9 – 23.0 kW

Standard seasonal efficiency (Hs)

Up to 98%

Seasonal central heating efficiency (ηS)

94%

Energy efficiency class

A

Sound power level (rated output)

46.1 dB(A)

Gas & Electrical

Gas types

Natural gas and LPG (configured at control unit)

Hydrogen compatibility

Up to 20% H2 blend

Natural gas supply pressure

20 mbar

LPG supply pressure

50 mbar

Electrical supply

230V~, 50Hz

Power consumption (delivered condition)

67W

Dimensions & Connections

Height

700mm

Width

400mm

Depth

360mm

Weight (excl. water)

32kg

Flue gas connection

60mm

Ventilation air connection

100mm

Boiler flow and return

R 3/4"

Cold water and DHW connections

G 1/2"

Expansion Vessel

Capacity

8 litres

Pre-charge pressure

0.75 bar

Max. permissible operating pressure

3 bar

What cylinder output does this boiler support?

The 25kW model supports a continuous cylinder heating output of 2.9 to 23.0 kW, suiting a standard indirect cylinder for a medium-sized home.

Does this boiler require a mounting jig?

Yes, a pre-plumbing jig or valves/fittings pack for surface or flush mounting must be ordered separately.

How quiet is this boiler in operation?

At its rated output the 25kW model has a sound power level of 46.1 dB(A), and drops to 31.9 dB(A) at partial load — among the quietest in its class.

Can this boiler be used in a multi-boiler cascade installation?

Yes, a multiple connection variant (B1HF-M) is available for vertical multiple connection or horizontal cascade setups.

BTU Calculator

BTU & WATT Calculator

Room Dimensions

Length (in m):

Width (in m):

Height (in m):

Room Type

Living Room

Bedroom

Kitchen

Bathroom

Conservatory

Hallway

Glazing Type

Single Glazed

Double Glazed

Triple Glazed

External Walls

0 Wall

1 Wall

2 Walls

3 Walls

4 Walls

Insulation Level

Poor

Average

Good (New Build)

Calculate

Required Heating

0

Watts

0

BTUs