Heat pumps · MT

Viessmann Vitocal 250-A AWO-E-AC 251.A19

The Viessmann Vitocal 250-A AWO-E-AC 251.A19 is an air-to-water heat pump with a SCOP of 4.86 (35 °C) and a sound power level of 48 dB(A).^1,2

Last updated: 27 September 2026Technical specifications Rules in Malta ⇄ Compare this model

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SCOP (35 °C): 4.86¹
Seasonal efficiency: how much heat you get per kWh of electricity across a heating season.
Heating capacity (A7/W35): 9kW²
Official source
Outdoor unit sound power: 48dB(A)¹
Official source
Refrigerant: R290¹
Official source
Type (source): Air-to-water¹
Official source

Rules in Malta

Water Heater Scheme (heat pump water heaters)

Unknown

REWS runs a national grant scheme for energy-efficient water heaters in homes; heat pump water heaters are eligible (alongside solar water heaters). The scheme has been extended to 31 December 2026, and part A of the application must be submitted before you buy and install the equipment. Grant amounts: see the REWS page (not verified by us).

Technical specifications

General
Type (source)	Air-to-water¹
Compressors	1¹
Capacity control	drehzahlregelung¹
Performance
Heating capacity (A7/W35)	9 kW²
Rated output 35 °C	13.61 kW¹
Rated output 55 °C	13.18 kW¹
Min. outdoor temperature	-20 °C²
Efficiency
SCOP (35 °C)	4.86¹
SCOP (55 °C)	3.88¹
Seasonal efficiency ηs 35 °C	191 %¹
Seasonal efficiency ηs 55 °C	152 %¹
Energy label 35 °C	A+++²
Energy label 55 °C	A+++²
COP A7/W35	5.27¹
COP A2/W35	4.06¹
COP A-7/W35	2.87¹
Noise
Outdoor unit sound power	48 dB(A)¹
Indoor unit sound power	40 dB(A)¹
Refrigerant
Refrigerant	R290¹
Refrigerant GWP	3²
Refrigerant charge	2 kg¹
Electrical
Max. power input	7.2 kW¹
Connectivity & smart
SG Ready	Yes¹

How it ranks

SCOP (35 °C): better than 61% of comparable models in our database (Heat pumps · Air-to-water · 10–14 kW; n = 308).

Rank 117 of 309

Compared with every model on VersusIndex in the same group with a known value; equal values do not count as better. This says nothing about price, installation or reliability.

Variants

This model is registered in 23 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 250-A AWO-E-AC 251.A19
Vitocal 250-A AWO-E-AC 251.A19 2C
Vitocal 250-A AWO-E-AC-AF 251.A19
Vitocal 250-A AWO-E-AC-AF 251.A19 2C
Vitocal 250-AH HAWO-AC 252.A19
Vitocal 250-AH HAWO-AC-AF 252.A19
Vitocal 252-A AWOT-E-AC 251.A19
Vitocal 252-A AWOT-E-AC 251.A19 2C
Vitocal 252-A AWOT-E-AC-AF 251.A19
Vitocal 252-A AWOT-E-AC-AF 251.A19 2C
Vitocal 250-A AWO-E-AC 251.A19
IDU-A Compact 2C AWMIT.A1.19-V056 ODU 250-A AWMOF-251.A1.19-400-V002
IDU-A Compact AWMIT.A1.19-V053 ODU 250-A AWMOF-251.A1.19-400-V002
IDU-A Modular AWMIW.A1.19-V051 ODU 250-A AWMOF-251.A1.19-400-V002
Vitocal 250-A AWO-E-AC 251.A19 2C
Vitocal 250-A AWO-E-AC-AF 251.A19 2C
Vitocal 250-A AWO-E-AC-AF 251.A19
Vitocal 250-AH HAWO-AC 252.A19
Vitocal 250-AH HAWO-AC-AF 252.A19
Vitocal 252-A AWOT-E-AC 251.A19 2C
Vitocal 252-A AWOT-E-AC 251.A19
Vitocal 252-A AWOT-E-AC-AF 251.A19 2C
Vitocal 252-A AWOT-E-AC-AF 251.A19

Manufacturer documentation

Product page (viessmann.de)

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

Similar models

Other brands, same type and a comparable size.

Frequently asked questions

Which refrigerant does the Viessmann Vitocal 250-A AWO-E-AC 251.A19 use?

The Viessmann Vitocal 250-A AWO-E-AC 251.A19 uses R290.^1,2

Sources

List of eligible heat pumps (BEG) — Bundesamt für Wirtschaft und Ausfuhrkontrolle (BAFA) · accessed 27 Sept 2026
Heat Pump Keymark certificates — EHPA / DIN CERTCO (Heat Pump KEYMARK) · accessed 29 Sept 2026
Water Heater Scheme (heat pump water heaters) — Regulator for Energy and Water Services (REWS)

Key figures