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ViessmannVITOCAL 333-G BWT 331.C12

The Viessmann VITOCAL 333-G BWT 331.C12 is a heat pump with SCOP (35 °C) 5.32 and refrigerant R410A.1,2

Last updated: Technical specifications Rules in the UK ⇄ Compare this model
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SCOP (35 °C)
5.321

Seasonal efficiency: how much heat you get per kWh of electricity across a heating season.

Refrigerant
R410A1
Official source
Type (source)
Ground source1
Official source
Rated output 35 °C
12kW1
Official source
Rated output 55 °C
12kW1
Official source
UK

Rules in the UK

Boiler Upgrade Scheme

Check conditions

£7,500 – £9,0003Fixed grant (England & Wales)

Fixed grant in England and Wales, deducted from your installer’s quote. £9,000 when replacing oil or LPG off the gas grid (until March 2027). Scotland: Home Energy Scotland grant instead.4,5

  • Must be MCS-certified (product and installer). Check the Ofgem product eligibility list.
  • Rated output 12 kW; the scheme covers systems up to 45 kW.
  • SCOP at 55 °C: 3.98. The installed system needs a SCOP of at least 2.8 (MCS calculation).
Heat pump grants in the UK explained →

Technical specifications

General
Type (source) Ground source1
Compressors 11
Capacity control drehzahlregelung1
Performance
Rated output 35 °C 12 kW1
Rated output 55 °C 12 kW1
Efficiency
SCOP (35 °C) 5.321
SCOP (55 °C) 3.981
Seasonal efficiency ηs 35 °C 205 %1
Seasonal efficiency ηs 55 °C 151 %1
Energy label 35 °C A, , 2
Noise
Indoor unit sound power 41 dB(A)1
Refrigerant
Refrigerant R410A1
Refrigerant GWP 2,0882
Refrigerant charge 2.3 kg1
Electrical
Max. power input 1.1 kW1
Connectivity & smart
SG Ready Yes1

Variants

This model is registered in 2 combinations (for example with a different indoor unit or cylinder) with exactly the same performance. All figures on this page apply to each of these types. The part of the type number that differs is in bold; small differences (e.g. cylinder volume or anode) are listed after it:

  • VITOCAL 333-G BWT 331.C12
  • Vitocal 300-G BWC 301.C12 (Sole / Wasser) — Max. power input: 1.11 kW

Manufacturer documentation

External links to Viessmann's official website. The manufacturer may change or move documents; where they differ, the manufacturer's latest version applies.

Frequently asked questions

What is the SCOP (35 °C) of the Viessmann VITOCAL 333-G BWT 331.C12?

The SCOP (35 °C) of the Viessmann VITOCAL 333-G BWT 331.C12 is 5.32.1,2

Which refrigerant does the Viessmann VITOCAL 333-G BWT 331.C12 use?

The refrigerant of the Viessmann VITOCAL 333-G BWT 331.C12 is R410A.1,2

How much Boiler Upgrade Scheme grant can you get for the Viessmann VITOCAL 333-G BWT 331.C12?

£7,500 in England and Wales, provided the product and installer are MCS-certified (£9,000 when replacing oil or LPG off the gas grid, until March 2027). The installer applies and deducts the grant from your quote.1,2

Sources

  1. List of eligible heat pumps (BEG) — Bundesamt für Wirtschaft und Ausfuhrkontrolle (BAFA) · accessed 29 Sept 2026
  2. Heat Pump Keymark certificates — EHPA / DIN CERTCO (Heat Pump KEYMARK) · accessed 29 Sept 2026
  3. Boiler Upgrade Scheme: what you can get — GOV.UK · accessed 27 Sept 2026
  4. Boiler Upgrade Scheme: guidance for installers (V5) — Ofgem · accessed 27 Sept 2026
  5. Boiler Upgrade Scheme product eligibility — Ofgem · accessed 27 Sept 2026