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Vaillant ecoTEC plus 835 35kW combi vs Viessmann Vitocal 150-A10

The Vaillant ecoTEC plus 835 35kW combi is a gas combi boiler, 35 kw hot water output. The Viessmann Vitocal 150-A10 is a r290 air source heat pump, 7.3 kw heat output.

Last reviewed 13 September 2026

Vaillant ecoTEC plus 835 35kW combi
Vaillant ecoTEC plus 835 35kW combi - image: PlumbNation
Vitocal 150-A10
Viessmann Vitocal 150-A10

Specifications side by side

Vaillant ecoTEC plus 835 35kW combiViessmann Vitocal 150-A10
Dimensions720 x 440 x 372 mm920 x 450 x 360 mm (H x W x D) (indoor unit); 841 x 1144 x 600 mm (H x W x D, single fan) (outdoor unit)
Hot water output35 kW-
Central heating output32.8 kW-
ErP classA-
Seasonal efficiency94%-
Warranty10 years with Vaillant Advance Boiler Protection Kit-
Hot water flow rate14.3 litres per minute-
Heat output-7.3 kW at A7/W35
COP-4.7-5.0 at A7/W35
Refrigerant-R290 (propane), GWP 0.02
Sound power-51 dB(A) assessed total at A7/W55
Weight-162 kg (single fan) (outdoor unit)
Max flow temperature-70C down to -10C outdoor

Sources: Vaillant ecoTEC plus 835 35kW combi, Viessmann Vitocal 150-A10. Figures vary by model year and options, so check with the supplier before you commit.

Buy or hire the ecoTEC plus 835 35kW combi if...

A gas combi boiler with 35 kW of hot water output, sized for a larger house with two bathrooms. It delivers about 14.3 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 10 years with Vaillant Advance Boiler Protection Kit. Seasonal efficiency is 94%.

Full ecoTEC plus 835 35kW combi specifications →

Buy or hire the Vitocal 150-A10 if...

A Vitocal 150-A monobloc-style split heat pump using the natural refrigerant R290, rated at 7.3kW and reaching a 70C flow for boiler-replacement work. Viessmann-trained installers can extend the standard warranty on registration.

Full Vitocal 150-A10 specifications →

Common questions

What is the difference between the Vaillant ecoTEC plus 835 35kW combi and the Viessmann Vitocal 150-A10?

The Vaillant ecoTEC plus 835 35kW combi is a gas combi boiler, 35 kW hot water output; the Viessmann Vitocal 150-A10 is a r290 air source heat pump, 7.3 kW heat output.

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