Baxi · Heat-pump or fixed-AC model
Baxi Assure HP55
Baxi Assure HP55 is the residential specification-channel counterpart to the HP60, using R290 refrigerant in five output designations with single-phase and selected three-phase versions.
Specifications
| Specification | Value |
|---|---|
| Type | ASHP, air-to-water monobloc, inverter-driven |
| Models | Assure HP55-4-1-PHMB, Assure HP55-6-1-PHMB, Assure HP55-8-1-PHMB, Assure HP55-11-1-PHMB, Assure HP55-11-3-PHMB, Assure HP55-13-1-PHMB and Assure HP55-13-3-PHMB |
| Product codes | 7899701 to 7899707 in model order |
| Rated output (kW) | 4.28, 5.44, 7.29, 10.30, 10.30, 11.50 and 11.50 |
| Rated-output conditions | nominal output at -5°C outdoor and 55°C flow, in model order |
| SCOP (seasonal coefficient of performance) at 35°C | Baxi table: 5.34, 5.22, 5.20, 4.77, 4.77, 4.70 and 4.70; MCS: 5.05, 4.99, 4.97, 4.59, 4.59, 4.53 and 4.53 |
| SCOP at 55°C | Baxi table: 3.99, 3.90, 3.89, 3.75, 3.75, 3.73 and 3.73; MCS: 3.76, 3.59, 3.65, 3.60, 3.60, 3.56 and 3.56 |
| Maximum flow temperature (°C) | 75 at -10°C outdoor |
| Minimum operating temperature (°C) | -25 |
| Refrigerant | R290 (propane), GWP 3; 0.7 to 1.25 kg by model |
| Sound power (dB) | 48, 48, 49, 52, 52, 52 and 52 dB(A) |
| Sound pressure at stated distance (dB) | 40, 40, 41, 44, 44, 44 and 44 dB(A) at 1 m |
| MCS certified | yes, CN-MCS-250009/02, /04, /06, /08, /12, /10 and /14 in model order |
| Warranty (years) | 2 years standard; up to 7 years enhanced, subject to Baxi terms |
| Dimensions, height × width × depth (mm) | Jan 2026 guide W x H x D: 1301 x 725 x 426 for 4/6 kW and 1390 x 872 x 523 for 8-13 kW; live page labels the larger casing W872 x H523 x D1390 |
Baxi Assure HP55 is an R290 air-to-water monobloc range intended for residential specification and social-housing projects. Baxi describes it as having the same features and benefits as the mainstream HP60, with separate Assure model names and MCS records.
Five outputs and two supply arrangements
The range has 4, 6, 8, 11 and 13 kW designations. All are available in single phase. Three-phase versions are added at 11 and 13 kW, producing seven exact model numbers in total. Baxi’s live HP55 page and January 2026 guide assign product codes 7899701 to 7899707 in the model order shown above.
Baxi’s technical table lists nominal and maximum capacity at different combinations of outdoor and water temperature. The structured specification uses nominal output at -5°C outdoor and 55°C flow. The family name alone is not a design output at every condition.
Published seasonal figures
The Assure HP55 page gives the same SCOP (seasonal coefficient of performance) table as the HP60 page. These values are higher than those in the live MCS records for each corresponding HP55 model. The 4 kW column, for example, is 5.34 at 35°C and 3.99 at 55°C on Baxi’s page, compared with 5.05 and 3.76 in MCS.
The exact figure used in an installation document should come from the source that document requires, with the complete HP55 model number shown.
System context
Baxi publishes a maximum flow temperature of 75°C at -10°C outdoor air. The smaller 4 and 6 kW casing measures 1301 mm wide, 725 mm high and 426 mm deep and weighs 94 kg. For models from 8 to 13 kW, the January 2026 guide gives 1390 mm wide, 872 mm high and 523 mm deep, consistent with the casing drawing. The live HP55 page transposes those labels to 872 mm wide, 523 mm high and 1390 mm deep. The published conflict remains unresolved. Net weights range from 122 kg to 142 kg.
The Baxi ASHP Control is required unless an HP55 is installed with the Baxi ASHP Pre-plumbed Cylinder. The conventional Baxi ASHP Cylinder is also listed as compatible, but it does not remove the separate-controller requirement.
Baxi lists the HP55 as current at 22 July 2026. Its ASHP guide gives a two-year standard warranty, while the product page advertises an enhanced term of up to seven years subject to its terms. The MCS Product Directory has seven current exact-model records under CN-MCS-250009.
Related entries
Brand
Reference type
Heat-pump or fixed-AC model
Last reviewed
22 Jul 2026
Current status
Current in the manufacturer's UK range.