If you are shortlisting a VRF heat pump for a large site, you want real model data, clear selection guidance, and credible fault finding. This guide gives you exactly that for Mitsubishi Electric City Multi Y Series. It focuses on PUHY P250YNW A2 and the surrounding range. It covers product fit, headline specifications, install limits, and the fault codes engineers meet most often. It also links you to manufacturer sources so you can verify the numbers fast. [1][2][3][4]
Explore our commercial installation services:
https://www.climateworks.co.uk/commercial-air-conditioning
What the Y Series is built for
The Y Series is a two pipe VRF heat pump platform. One outdoor unit serves many indoor units. It delivers either heating or cooling to the connected spaces at a given time. It suits multi zone offices, retail floors, education buildings, and managed workspaces where simultaneous dual mode is not required. The range spans standard outdoor modules from roughly 22 kilowatts to 50 kilowatts per chassis, with twinned options for higher duties. Indoor unit options cover wall, floor, cassette, ducted, and specialist formats. [1]
Where PUHY P250YNW A2 sits in the line up
PUHY P250YNW A2 is a standard outdoor module in the current YNW A2 generation. It is part of a family that includes P200, P250, P300, and twin frame variants such as P350 and P400. The P250 module is a common choice on mid to large floors because it balances capacity, footprint, and sound output while keeping the pipe sizes practical. [1]
Key outdoor models and headline figures
Figures below are taken from the Mitsubishi Electric UK Y Series standard brochure for the YNW A2 generation. Values are nominal at standard rating points. Always check the latest data book and selection software for your project. [1]
PUHY P200YNW A2 to PUHY P300YNW A2
- PUHY P200YNW A2
- Nominal cooling 22.4 kilowatts
- Nominal heating 25.0 kilowatts
- Nominal power input 6.03 to 6.08 kilowatts
- COP and EER at nominal 4.11 and 3.71
- Sound pressure 59.0 to 58.0 dBA
- Dimensions height 1858 millimetres, width 920, depth 740
- Refrigerant R410A
- Single frame module. [1]
- PUHY P250YNW A2
- Nominal cooling 28.0 kilowatts
- Nominal heating 31.5 kilowatts
- Nominal power input 8.49 to 10.70 kilowatts depending on mode
- COP and EER at nominal 3.71 and 2.91
- Sound pressure 61.0 to 60.0 dBA
- Dimensions height 1858 millimetres, width 1240, depth 740
- Gas pipe 22.2 millimetres, liquid pipe 9.52 millimetres
- Refrigerant R410A
- Single frame module. [1]
- PUHY P300YNW A2
- Nominal cooling 35.6 kilowatts
- Nominal heating 37.5 kilowatts
- Nominal power input 10.30 to 13.70 kilowatts
- COP and EER at nominal 3.65 and 2.86
- Sound pressure 64.5 to 61.0 dBA
- Dimensions height 1858 millimetres, width 1240, depth 740
- Gas pipe 28.58 millimetres, liquid pipe 12.7 millimetres when runs are longer
- Refrigerant R410A
- Single frame module. [1]
Twin frame high duty variants
- PUHY P350YNW A2 and PUHY P400YNW A2
- Twin frame outdoor set
- Nominal cooling 40.1 to 45.5 kilowatts and nominal heating 45.0 to 50.0 kilowatts across the two modules
- Combined sound pressure 62.0 to 61.0 dBA per module
- Gas pipe 28.58 millimetres, liquid pipe 12.7 millimetres
- Dimensions per module height 1858 millimetres, width 920, depth 740
- Refrigerant R410A. [1]
For ERP documentation on PUHY P250YNW A2, including fan VSD details and declared year of manufacture bands, see the Mitsubishi Electric ERP file. [2]
Indoor unit families you can connect
The value of Y Series is the breadth of compatible indoor units. Selection depends on ceiling type, zone size, and finish level.
- Wall mounted
Good for staff rooms, clinics, and small offices where a simple installation is needed. - Floor mounted
Useful where wall space is limited or where low level air throw suits the room. - Four way ceiling cassette
Suits suspended ceiling grids on open plan floors and retail units. - Slim ducted
Ideal when you need a discreet finish with linear grilles and balanced air paths. - High static ducted
Used for larger zones and deeper ceiling voids where longer duct runs are planned.
All are available in multiple sizes so you can match room gains and maintain coil performance with reasonable fan speed. The UK Y Series brochure lists the maximum number of connectable indoor units and total connected capacity ratio. The quoted range is 50 percent to 130 percent of outdoor nameplate, which supports diversity planning on multi zone floors. [1]
Controls, BMS, and zoning
The platform supports local wired controllers, group control, and centralised touch screens. A gateway can link the system to BMS over common protocols. This allows tenant billing, schedule control, and trend logging. The City Multi literature states that a single system can serve a large number of indoor units by using branch controllers and headers. It is standard to split floors into zones by orientation and usage to simplify operation. [13]
Installation constraints you must check
Pipe design is critical on VRF. Observe total length, maximum height difference, and branch rules. The City Multi design and installation manuals give the limits for the Y platform. A few common checks follow. Always verify against the exact model manual.
- Maximum operating pressure for R410A systems is quoted at 4.30 megapascals. Pipe grade and wall thickness must meet this. Use copper types stated by the manufacturer. [1][3]
- Branching must follow the home run and T branch rules. Header kits and twinning kits have specific positions. Keep the total length across the first four branches within the stated limit. [3]
- Size liquid and gas lines as per the outdoor model and the furthest length. The Y Series brochure notes that on P250 and P300, the liquid pipe can upsize to 12.7 millimetres when the furthest length exceeds a given threshold. [1]
- Allow clear working space around outdoor units. Respect the quoted side and rear clearances. Avoid recirculation by keeping discharge paths clear. Use roof upstands sized to the base dimensions shown. [1][4]
- Check mains supplies and protective devices for each chassis. The brochure shows typical starting current, running current, and suggested breaker ratings. Follow the data book for cable sizing. [1]
Use the official design guide and the installation manual for the exact system you are building. These documents include selection charts, refrigerant charge calculations, oil traps, and field wiring schematics. [3][1]
Acoustic planning
The published sound pressure levels for P200 to P300 run from the high fifties to the mid sixties dBA at the standard measurement distance. Twin frame sets list similar values per module. Place units away from sensitive façades where possible and consider the adjustable low noise modes that the YNW generation offers. The New Zealand brochure notes multiple low noise patterns to suit site conditions. [6]
Service access and maintainability
Provide front and side access to electrical panels, filters, and fans. Keep at least the clearance shown in the outline drawings. Maintain lift and tie down points. Dimension drawings and centre of gravity data for P200 to P300 can be found in the manufacturer dimensional PDF so your steelwork and cranage team can plan safely. [4]
Indoor unit selection examples
- Small meeting rooms
Wall mounted or compact cassette, sized at roughly 2.0 to 3.5 kilowatts per room depending on gains. - Open plan office bays
Four way cassettes or slim ducted units. Space them based on throw and NC targets. - Boardrooms and training rooms
Ducted units with linear grilles for a cleaner visual and better diffusion. - Back of house rooms
Wall or floor units where a simple install keeps cost and lead time down.
These choices allow mixed aesthetics and maintain balanced pressures across shared ceiling voids.
Commissioning steps that avoid call backs
- Pressure test with dry nitrogen to the level stated by the manual. Hold and record.
- Evacuate to target microns and prove stability.
- Check valve positions before charging and during start up.
- Confirm indoor addresses, refrigerant address settings, and controller groupings.
- Balance fan speeds to hit noise and throw targets.
- Record controller settings and hand them to the site team with the O and M pack.
The service handbooks and commissioning guides set these steps out in sequence for the Y Series outdoor model family. [14][3]
Fault codes engineers report most, with likely causes and first checks
Always confirm codes using the official error code lookup or the City Multi fault list, then move to detailed diagnostics in the service handbook. The notes below are field triage prompts, not a substitute for the manual. [2][3][14]
- 1301 low pressure fault
Likely issues- Low charge or a restriction
- Low outdoor airflow
First checks - Confirm service valves fully open
- Compare LP sensor reading with gauge
- Inspect outdoor fan and coil condition. [3]
- 1302 high pressure fault
Likely issues- Blocked airflow or overcharge
- Liquid line restriction
First checks - Clear outdoor coil and check fans
- Review LEV position and subcooling trend. [3]
- Indoor to outdoor communication error
Likely issues- Polarity error on MNET wiring
- Address conflict after a device swap
First checks - Check continuity and polarity
- Reconfirm addresses on all boards. [2][14]
- Thermistor fault on an indoor unit
Likely issues- Open or short on the sensor line
- Damaged plug at the PCB
First checks - Measure resistance against the table
- Reseat or replace the sensor. [11][14]
- Drain pump fault on cassette
Likely issues- Pump stuck, float switch triggered
First checks - Clean the trap and check pump voltage
- Test float switch operation. [11]
Use the online Mitsubishi Electric error code lookup for rapid hints, then turn to the relevant Y Series service handbook for the full tree. [2][14]
How this maps to real projects
A typical two floor office in Reading might use one P250 outdoor on the roof, feeding a mix of ducted units over open plan desks, cassettes in collaboration areas, and small wall units in focus rooms. You would size connected capacity to a diversity of around one hundred to one hundred and twenty percent based on gains and simultaneity. You would group zones by orientation so the morning solar load and afternoon load are covered without large control swings. You would route the main liquid and gas risers in a single core and branch at corridors using the approved branch joints and headers. You would keep the longest run within the model limit, then apply the upsized liquid line when distances push past the threshold noted in the brochure footnote. [1][3]
For a larger fit out in Guildford you might twin two modules to reach a nameplate in the forties. You would plan crane lifts using the centre of gravity data and base bolt pattern. You would set the low noise mode for night hours to support local planning conditions. You would hand over with recorded commissioning sheets and a controller quick guide for the client FM lead. [4][6][1]
When to choose Y Series rather than R2
Pick Y when the site only needs one mode at a time across the connected zones, or when the value case points to a simpler pipe network and lower install complexity. Pick R2 when true simultaneous heating and cooling is required across many zones on the same system. If in doubt, review the floor adjacency and expected usage in the design workshop.
Related pages
References
[1] Mitsubishi Electric UK. City Multi Y Series Standard YNW A2 brochure including PUHY P200 to P400. September 2022. PDF.
[2] Mitsubishi Electric Europe ERP technical sheet. PUHY P250YNW A2. PDF.
[3] Mitsubishi Electric. City Multi installation and design manuals for Y Series including PUHY P YNW A models. PDF.
[4] Mitsubishi Electric. Dimensional and centre of gravity drawings for PUHY P200, P250, P300 YNW A2. PDF.
[5] Mitsubishi Electric and partners. City Multi range overview and multi zone control notes. PDF.
[6] Mitsubishi Electric New Zealand. Y Series low noise mode options in YNW generation. Brochure. PDF.
[7] Mitsubishi Electric UK. Error code lookup portal for installers.
[8] Mitsubishi Electric Singapore. City Multi error code list. PDF.
Author bio
Dr. Julian Carter is a highly experienced thermal systems expert with over 15 years in the field, holding a PhD in thermal systems. His career spans academic research, consulting, and teaching, focusing on air conditioning and refrigeration systems. Dr. Carter bridges the gap between theoretical advancements and practical applications, providing expert insights to organisations like ClimateWorks, where his guidance informs decision-making and industry best practices. Notably, he has worked on international projects with organisations such as Daikin Industries, the International Institute of Refrigeration, and the United Nations Environment Programme. These collaborations addressed energy performance, sustainable refrigerants, and advanced cooling technologies. Currently a lecturer at Edinburgh University, Dr. Carter combines his expertise with a passion for educating the next generation of engineers and advancing climate control technologies.
.png){kind=small}
