Heat pumps · UK

Viessmann Vitocal 250-A IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002

The Viessmann Vitocal 250-A IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002 is an air-to-water heat pump with a SCOP of 4.57 (35 °C) and a sound power level of 46 dB(A). Under permitted development the limit is 37 dB(A) measured 1 m in front of the centre of a neighbour’s habitable-room door or window. Free-standing, the indicative minimum distance is 1.1 m; against a wall 1.6 m.^1,2

Last updated: 29 September 2026Technical specifications Rules in the UK ⇄ Compare this model

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SCOP (35 °C): 4.57¹
Seasonal efficiency: how much heat you get per kWh of electricity across a heating season.
Heating capacity (A7/W35): 4kW²
Official source
Outdoor unit sound power: 46dB(A)¹
Official source
Refrigerant: R290¹
Official source
Type (source): Air-to-water¹
Official source

Rules in the UK

Minimum distance to your neighbour

MCS 020(a) (England, permitted development since 29 May 2025)³ · 1 m in front of the centre of a neighbour’s habitable-room door or window

Permitted development (MCS 020(a))≤ 37 dB(A) · LAeq,5min

Free-standing1.1 m

Against wall1.6 m

In corner2.2 m

Indicative calculation (hemispherical, no barriers). Not a substitute for an MCS 020 assessment.

Boiler Upgrade Scheme

Check conditions

£7,500 – £9,000⁴Fixed 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.^5,6

Must be MCS-certified (product and installer). Check the Ofgem product eligibility list.
Rated output 4.08 kW; the scheme covers systems up to 45 kW.
SCOP at 55 °C: 3.33. 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)	Air-to-water¹
System	Hybrid (with gas boiler)¹
Compressors	1¹
Capacity control	Inverter¹
Performance
Heating capacity (A7/W35)	4 kW²
Rated output 35 °C	4.08 kW¹
Rated output 55 °C	3.77 kW¹
Min. outdoor temperature	-20 °C²
Efficiency
SCOP (35 °C)	4.57¹
SCOP (55 °C)	3.33¹
Seasonal efficiency ηs 35 °C	180 %¹
Seasonal efficiency ηs 55 °C	130 %¹
Energy label 35 °C	A+++²
Energy label 55 °C	A++²
COP A7/W35	5.73¹
COP A2/W35	4.42¹
COP A-7/W35	3.18¹
Noise
Outdoor unit sound power	46 dB(A)¹
Indoor unit sound power	40 dB(A)¹
Refrigerant
Refrigerant	R290¹
Refrigerant GWP	3²
Refrigerant charge	1.2 kg¹
Electrical
Max. power input	0.78 kW¹
Connectivity & smart
SG Ready	Yes¹

How it ranks

SCOP (35 °C): better than 27% of comparable models in our database (Heat pumps · Air-to-water · 4–6 kW; n = 122).

Rank 89 of 123

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 3 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 IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002
IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002
IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002

Manufacturer documentation

Datasheet / specifications — Datenblatt Vitocal 250-A Hybrid (viessmann.de, PDF)
Brochure / leaflet — Prospekt Vitocal 250-A Hybrid (viessmann.de, PDF)

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

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Frequently asked questions

Can I install the Viessmann Vitocal 250-A IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002 without planning permission?

Under MCS 020(a) (England, permitted development since 29 May 2025) the unit must not exceed 37 dB(A) 1 m in front of the centre of a neighbour’s habitable-room door or window. With a sound power of 46 dB(A) that indicatively means 1.1 m free-standing, 1.6 m against a wall or 2.2 m in a corner. Your MCS installer must confirm this.^1,2

How much Boiler Upgrade Scheme grant can you get for the Viessmann Vitocal 250-A IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002?

£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

Which refrigerant does the Viessmann Vitocal 250-A IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002 use?

The Viessmann Vitocal 250-A IDU-A Hybrid HWMIW.A1.19-V054 / ODU 250-A AWMOF-251.A1.04-230-V002 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
MCS 020(a) (England, permitted development since 29 May 2025)
Boiler Upgrade Scheme: what you can get — GOV.UK · accessed 27 Sept 2026
Boiler Upgrade Scheme: guidance for installers (V5) — Ofgem · accessed 27 Sept 2026
Boiler Upgrade Scheme product eligibility — Ofgem · accessed 27 Sept 2026

Key figures