Solar DHW CylinderauroSTEP plus VIH S1 150-350l

The monovalent solar cylinder designed to deliver durability and efficiency.

Energy-saving hot water generation through solar energy
Drain-back technology for a long-lasting, worry-free system
Three tank sizes to suit every household
Compact design through smart integration
Reliable hot water comfort, even without sufficient sunlight

auroSTEP plus is the heart of Vaillant's drain-back solar system, harnessing free solar energy to cover up to 80% of the domestic hot water needs of families of 2 to 6 people. More compact and faster to install than traditional solar systems, it offers reliable protection against the two most common threats to rooftop collectors: overheating and freezing. Once the desired water temperature is reached, the solar fluid drains automatically from the collectors — no overheating, no system stress, no fluid degradation. In winter, the same mechanism protects against freezing, ensuring lasting performance and system longevity season after season.

Ideal for:

Hot water

Technical data table overline

Technical data table headline

auroSTEP plus
VIH S1 150/4 B	VIH S1 250/4 B	VIH S1 350/4 B

ErP

ErP Energy Efficiency Class Hot Water Storage Tanks	ErP Energy Efficiency Class Hot Water Storage Tanks

auroSTEP plus
VIH S1 150/4 B	VIH S1 250/4 B	VIH S1 350/4 B

Cylinder

Cylinder Nominal Capacity	Cylinder Nominal Capacity	162 l	246 l	330 l
Cylinder Part Capacity, Standby Content	Cylinder Part Capacity, Standby Content	68 l	117 l	138 l
Cylinder Part Capacity, Solar	Cylinder Part Capacity, Solar	94 l	129 l	192 l

Heat Exchanger

Heat Exchanger Solar (Heating Area / Heat Exchanger Content)	Heat Exchanger Solar (Heating Area / Heat Exchanger Content)	1,3 m² / 8,9 l	1,3 m² / 8,9 l	1,6 m² / 10 l
Heat Exchanger Heating (Heating Area / Heat Exchanger Content)	Heat Exchanger Heating (Heating Area / Heat Exchanger Content)	0,7 m² / 5 l	0,8 m² / 5 l	0,7 m² / 5 l

Domestic Hot Water

Initial Domestic Hot Water Output (flow = 45 °C)	Initial Domestic Hot Water Output (flow = 45 °C)	87 l/10min	155 l/10min	203 l/10min
NL-Figure	NL-Figure	0,7	1,2	2,2

Insulation And Heat Loss

Standby Heat Loss	Standby Heat Loss	1,25 kWh/24h	1,56 kWh/24h	1,7 kWh/24h

Connections

Connection Dimension Heating (Flow, Return)	Connection Dimension Heating (Flow, Return)	R 1″	R 1″	R 1″
Connection Dimension Cold Water, Domestic Hot Water	Connection Dimension Cold Water, Domestic Hot Water	R ¾″	R ¾″	R ¾″
Connection Dimension Circulation	Connection Dimension Circulation	R ¾″	R ¾″	R ¾″

Dimensions

Height / Width / Depth	Height / Width / Depth	1.065 mm / 600 mm / 600 mm	1.596 mm / 600 mm / 600 mm	1.778 mm / 690 mm / 690 mm
Weight	Weight	86 kg	123 kg	163 kg
Weight Ready for Operation	Weight Ready for Operation	248 kg	384 kg	512 kg
Tilt Dimension	Tilt Dimension	1.222 mm	1.650 mm	1.835 mm

Limitations

Operating Pressure Domestic Hot Water (max)	Operating Pressure Domestic Hot Water (max)	10 bar	10 bar	10 bar
Operating Pressure Heating (max)	Operating Pressure Heating (max)	3 bar	3 bar	3 bar
Operating Pressure Solar (max)	Operating Pressure Solar (max)	6 bar	6 bar	6 bar
Temperature Domestic Hot Water (max)	Temperature Domestic Hot Water (max)	85 °C	85 °C	85 °C
Temperature Solar (max)	Temperature Solar (max)	130 °C	130 °C	130 °C
Temperature Heating (max)	Temperature Heating (max)	90 °C	90 °C	90 °C