The Hitachi Yutaki S80 Very High Temperature indoor unit is a boiler-replacement air-to-water heat pump built around a twin-refrigerant Smart Cascade cycle, combining an R410A first stage with an R134a second stage to deliver hot water up to 80°C even at -20°C outdoor ambient — without any supplementary electric back-up. This variant page covers the three single-phase indoor unit sizes in the range: RWH-4.0VNFE (11kW), RWH-5.0VNFE (14kW) and RWH-6.0VNFE (16kW).
Each indoor unit is a Type 1 (remote tank) configuration, designed to pair with a Hitachi RAS-WH(V)NP(E) outdoor unit and, where domestic hot water is required, a separately ordered PC-ARFHE unit controller and remote DHW cylinder. The units are ideal for refurbishment projects replacing oil or gas boilers, where existing high-temperature radiators need to be retained rather than replaced.
11-16kW
Heating capacity range
80°C
Max. water outlet temp.
Up to 5.0
COP (7°C/30-35°C)
-25 to +25°C
Heating operating range
R410A + R134a
Smart Cascade refrigerant
1-Phase
Electrical supply (230V)
Qualified Installation Required
This is an R410A / R134a split air-to-water heat pump system requiring installation, commissioning and refrigerant work by a Gas Safe / F-Gas qualified engineer in accordance with Hitachi's installation manual. A compulsory first start-up, carried out by Hitachi Technical Service, is required before the system may be operated.
System Components Sold Separately
The indoor unit alone does not include the outdoor unit (RAS-WH(V)NP(E) series), the PC-ARFHE remote controller (required for Type 1 DHW-with-remote-tank operation), or the domestic hot water cylinder. Confirm the correct outdoor unit pairing and accessory list at quote stage, as detailed hydraulic and electrical data for this exact indoor-unit line was not confirmed in the manufacturer documentation available at time of writing and has therefore been omitted from the specification table below.
Smart Cascade Technology
Hitachi's Smart Cascade control automatically decides whether the R134a second stage needs to run, bypassing it during milder conditions so the unit relies on the more efficient first stage alone. During cold spells or high-temperature demand, the second stage engages to guarantee full output and 80°C water production even at -20°C outside air temperature.
Model Variants
| Model |
Heating Capacity |
Phase |
Max. Water Outlet |
COP (7°C/35°C) |
Dimensions (H x W x D) |
| RWH-4.0VNFE |
11 kW |
1-phase, 230V |
80°C |
Up to 5.0 |
600 x 623 x 802 mm |
| RWH-5.0VNFE |
14 kW |
1-phase, 230V |
80°C |
Up to 5.0 |
600 x 623 x 802 mm |
| RWH-6.0VNFE |
16 kW |
1-phase, 230V |
80°C |
Up to 5.0 |
600 x 623 x 802 mm |
Twin-Cycle Cascade Design
A dedicated R134a heat pump circuit boosts water from mid-range to 80°C instead of relying on an electric immersion element, so high-temperature output is achieved without the running costs of resistive heating.
Constant Output in Deep Cold
Rated heating capacity is maintained down to -15°C, and the unit continues to deliver 80°C water at -20°C outdoor air — addressing the output collapse that limits many single-cycle air source heat pumps in winter.
Drop-In Boiler Replacement
Designed to work with the existing radiator circuit in a property, avoiding the cost and disruption of replacing emitters when switching a home from a gas or oil boiler to a heat pump.
Two Independent Heating Zones
Built-in provision for two water output zones (for example underfloor heating plus radiators) allows a single indoor unit to serve mixed-emitter properties from one heat source.
Weather Compensation Control
The unit controller continuously adjusts flow temperature against outdoor conditions, reducing flow temperatures whenever possible to protect seasonal efficiency rather than running at a fixed high setpoint year-round.
Solar & BMS Ready
Compatible with solar thermal integration and, via the optional Konnex interface, BMS/KNX building management systems for centralised control in larger properties.
Full Specification
| Model Range |
| Model code — 11kW |
RWH-4.0VNFE |
| Model code — 14kW |
RWH-5.0VNFE |
| Model code — 16kW |
RWH-6.0VNFE |
| Type |
Type 1 — DHW operation with remote (separately supplied) tank |
| Compatible outdoor unit |
Hitachi RAS-WH(V)NP(E) series (single phase) |
| Performance |
| Rated heating capacity range |
11 – 16 kW across the three sizes |
| COP (7°C outside / 30-35°C water) |
Up to 5.0 |
| Max. water outlet temperature |
80°C |
| Heating operating range |
-25°C to +25°C outdoor ambient |
| Cooling |
Not applicable — heating-only unit |
| Refrigerant System |
| 1st stage refrigerant |
R410A |
| 2nd stage (cascade) refrigerant |
R134a |
| 2nd stage refrigerant GWP |
1430 |
| Compressor type |
Scroll, DC Inverter |
| Electrical |
| Power supply |
230V / 1-phase / 50Hz |
| Indoor/outdoor communication |
H-LINK II, 2-wire, non-polarised |
| Physical |
| Dimensions (H x W x D) |
600 x 623 x 802 mm (each model) |
| Commodity code |
8415 83 00 |
| Required Accessories (Not Included) |
| Remote unit controller |
PC-ARFHE (required for Type 1 operation) |
| Domestic hot water tank |
Ordered separately — e.g. DHWS200S-2.7H2E / DHWS260S-2.7H2E range |
Frequently Asked Questions
What is the difference between the 11kW, 14kW and 16kW versions?
The three models — RWH-4.0VNFE, RWH-5.0VNFE and RWH-6.0VNFE — share the same cabinet, controls and Smart Cascade technology, and differ only in rated heating output (11kW, 14kW and 16kW respectively). The correct size depends on the property's calculated heat loss and domestic hot water demand, and should be confirmed against the matching outdoor unit selection.
Does this indoor unit include the outdoor unit or hot water cylinder?
No. This listing is for the indoor (hydraulic) unit only. A compatible Hitachi RAS-WH(V)NP(E) outdoor unit, a PC-ARFHE remote controller, and a domestic hot water cylinder must all be specified and ordered separately to complete the system.
Can this heat pump work with my existing radiators?
Yes — the Yutaki S80 Very High Temperature range is specifically designed to output up to 80°C water, making it suitable for existing high-temperature radiator systems without the emitter upgrades that lower-temperature heat pumps typically require.
Does output drop off in cold weather?
Rated heating capacity is maintained down to -15°C outdoor air, and the unit can still produce 80°C water at -20°C outdoor ambient without a supplementary electric heater, thanks to the second R134a refrigerant stage engaging automatically in cold conditions.
What qualifications does my installer need?
Installation involves refrigerant pipework across two circuits (R410A and R134a) and must be carried out and commissioned by a suitably qualified, F-Gas certified heating engineer, with a compulsory first start-up performed by Hitachi Technical Service before the system is handed over.
Is a solar thermal or BMS connection possible?
Yes. The Yutaki S80 control system supports solar thermal integration and, via the optional Konnex interface accessory, connection to KNX-based building management systems for centralised monitoring and control.
