Head to head
Telford Tempest 170 Direct vs Viessmann Vitocal 150-A06
The Telford Tempest 170 Direct is a direct unvented hot water cylinder, 170 litres. The Viessmann Vitocal 150-A06 is a r290 air source heat pump, 4.8 kw heat output.
Last reviewed 13 September 2026
Specifications side by side
| Telford Tempest 170 Direct | Viessmann Vitocal 150-A06 | |
|---|---|---|
| Dimensions | 1200 mm high x 510 mm diameter (approx.) | 920 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) |
| Weight | 40 kg empty, 208 kg full | 162 kg (single fan) (outdoor unit) |
| Capacity | 170 litres | - |
| Immersion heater | 2 x 3kW, 240V single phase | - |
| Max inlet pressure | 3 bar (inlet control group) | - |
| Warranty | Lifetime guarantee on the cylinder (25 years internal), 2 years on components | - |
| Heat output | - | 4.8 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 |
| Max flow temperature | - | 70C down to -10C outdoor |
Sources: Telford Tempest 170 Direct, Viessmann Vitocal 150-A06. Figures vary by model year and options, so check with the supplier before you commit.
Buy or hire the Tempest 170 Direct if...
A 170 litre direct unvented cylinder from Telford's Tempest range, built in duplex stainless steel with twin 3kW immersions rather than a boiler coil. It suits an all-electric property, and the cylinder body carries a lifetime guarantee when serviced annually.
Full Tempest 170 Direct specifications →Buy or hire the Vitocal 150-A06 if...
A Vitocal 150-A monobloc-style split heat pump using the natural refrigerant R290, rated at 4.8kW and reaching a 70C flow for boiler-replacement work. Viessmann-trained installers can extend the standard warranty on registration.
Full Vitocal 150-A06 specifications →Common questions
What is the difference between the Telford Tempest 170 Direct and the Viessmann Vitocal 150-A06?
The Telford Tempest 170 Direct is a direct unvented hot water cylinder, 170 litres; the Viessmann Vitocal 150-A06 is a r290 air source heat pump, 4.8 kW heat output.
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