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Heat pumps · UK

A.O. Smith WWHB 40

The A.O. Smith WWHB 40 is a heat pump with SCOP (35 °C) 5.6 and refrigerant R134A.1,2

Last updated: Technical specificationsRules in the UK⇄ Compare this model
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SCOP (35 °C)
5.62

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

Refrigerant
R134A1
Official source
Type (source)
Water-to-water1
Official source
Rated output 35 °C
43kW2
Official source
Rated output 55 °C
39kW2
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 43 kW; the scheme covers systems up to 45 kW.
  • SCOP at 55 °C: 4.45. 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)Water-to-water1
Performance
Rated output 35 °C43 kW2
Rated output 55 °C39 kW2
Efficiency
SCOP (35 °C)5.62
SCOP (55 °C)4.452
Seasonal efficiency ηs 35 °C221 %2
Seasonal efficiency ηs 55 °C175 %2
Energy label 35 °CA+++2
Energy label 55 °CA+++2
Noise
Indoor unit sound power65 dB(A)2
Refrigerant
RefrigerantR134A1
Refrigerant GWP1,4301
Grants & market
ISDE grant (NL)8,775 €1

How it ranks

SCOP (35 °C): better than 20% of comparable models in our database (Heat pumps · Water-to-water · ≥ 14 kW; n = 65).

Rank 52 of 66

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.

Similar models

Other brands, same type and a comparable size.

More from A.O. Smith

Guides on heat pumps

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Frequently asked questions

What is the SCOP (35 °C) of the A.O. Smith WWHB 40?

The SCOP (35 °C) of the A.O. Smith WWHB 40 is 5.6.1,2

Which refrigerant does the A.O. Smith WWHB 40 use?

The refrigerant of the A.O. Smith WWHB 40 is R134A.1,2

How much Boiler Upgrade Scheme grant can you get for the A.O. Smith WWHB 40?

£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. ISDE heat pump notification code list — Rijksdienst voor Ondernemend Nederland (RVO) · accessed 28 Sept 2026
  2. European Product Registry for Energy Labelling (EPREL) – heat pumps — Europese Commissie · accessed 18 Oct 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