The Air Handling Unit Controller is an interface to allow connection to third party Air Handling Unit. It is designed to efficiently heat large amounts of air without the use of electric elements within an AHU, with the added bonus of cooling the air from a common outdoor unit.
Mitsubishi Electric City Multi outdoor units can be used with this interface box, creating and ideal solution when a unique air handling unit is required. The Air Handling Unit Controllers are supplied with LEV expansion device(s) which are fitted at time of manufacture to the DX coil in the AHU. Temperature sensors are fitted on both sides of the DX coil giving you the flexibility to sense and control to the air coming onto or air leaving the coil.

Air Handling Unit Controller

The fresh air requirements for commercial buildings, gymnasiums, halls or wherever there are large numbers of people inside, can be huge, often many cubic metres per second. With such large volumes of fresh outside air, comes the need to temper it, normally to around 18°C.

For very large air volumes or where the application of Lossnay is not possible to return-duct the exhaust air, you are faced with the job of heating the air in a ‘once through total loss’ system. Traditionally this has been done using an Air Handling Unit (AHU) with either hot water coils or electric element banks, neither of these options providing an effective COP or the ability to cool the incoming air.


  • Required = 3m3/s at 18°C indoors
  • Outside air temperature = 0°C
  • Required heating capacity = 65.34kW

In the past, unless there has been a central boiler plant handy, electric elements have been seen as the only viable option. In this case, the heating load would add just fewer than 100 amps load per phase to the building mains, increasing the load capacity, not to mention the additional electricity charges associated with maximum demand.

The New Solution The City Multi AHU Controller

The AHU Controller unit enables the connection of our standard range of City Multi outdoor units, to third party DX coil mounted in the AHU or ductwork.

The key is the sophisticated City Multi inverter controls and R410a refrigerant – the system can handle a coil air-on condition as low as -10°C. The control logic is factory set to provide leaving-air temperature control, making these units perfect for full, fresh air supply. The leaving-air temperature control is very stable as the inverter driven outdoor unit adjusts to meet the load. The COP in heating you can expect from our standard units is 3.8 to 4, and when using the high COP models – 4.3 to 4.4!

Not only does this system provide unbeatable energy efficiency in heating mode, it is able to run in cooling mode to ‘pre-cool’ fresh air in summer, reducing load on the air conditioning equipment installed.

The application of this product is not limited to new buildings, as it offers very significant opportunities for retro-fitting energy efficiency into existing systems. Savings in annual running costs, over electric element banks, will almost always be in the order of 75%, providing payback on capital expenditure that most customers would expect.

We now have available a very accurate energy logger to assist with identifying and verifying opportunities for retro fits of this product. If you have an opportunity that you wish to explore please contact a member of our City Multi team.