Head to head
Viessmann Vitodens 100-W 35kW combi vs Worcester Bosch Greenstar 5800i AW 5kW
The Viessmann Vitodens 100-W 35kW combi is a gas combi boiler, 34.9 kw hot water output. The Worcester Bosch Greenstar 5800i AW 5kW is a r290 monobloc air source heat pump, 6.80 kw heat output.
Last reviewed 13 September 2026
Specifications side by side
| Viessmann Vitodens 100-W 35kW combi | Worcester Bosch Greenstar 5800i AW 5kW | |
|---|---|---|
| Dimensions | 700 x 400 x 360 mm | 800 x 1100 x 540 mm (H x W x D) |
| Weight | 35 kg | 143 kg |
| Hot water output | 34.9 kW | - |
| Central heating output | 32 kW | - |
| ErP class | A | - |
| Seasonal efficiency | 98% | - |
| Warranty | 5 years | - |
| Hot water flow rate | 17 litres per minute | - |
| Heat output | - | 6.80 kW at 7/35C |
| SCOP | - | 4.53 (MCS, 35C flow) |
| Refrigerant | - | R290 (propane) |
| Sound pressure | - | 42 dB(A) |
| Max flow temperature | - | 75C |
Sources: Viessmann Vitodens 100-W 35kW combi, Worcester Bosch Greenstar 5800i AW 5kW. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the Vitodens 100-W 35kW combi if...
A gas combi boiler with 34.9 kW of hot water output, sized for a larger house with two bathrooms. It delivers about 17 litres per minute of hot water, which decides how well a shower runs while a tap is on. Warranty: 5 years. Seasonal efficiency is 98%.
Full Vitodens 100-W 35kW combi specifications →Buy or hire the Greenstar 5800i AW 5kW if...
Worcester Bosch's entry-size 5800i AW, using the natural refrigerant R290 and reaching a 75C flow temperature for existing radiator systems. It is marketed as one of the quieter units in this size at 42 dB(A) sound pressure.
Full Greenstar 5800i AW 5kW specifications →Common questions
What is the difference between the Viessmann Vitodens 100-W 35kW combi and the Worcester Bosch Greenstar 5800i AW 5kW?
The Viessmann Vitodens 100-W 35kW combi is a gas combi boiler, 34.9 kW hot water output; the Worcester Bosch Greenstar 5800i AW 5kW is a r290 monobloc air source heat pump, 6.80 kW heat output.
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