Dual-purpose heat pump chiller for hospital

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Published: 30 November 2017


heat pump chiller roof heating cooling dx
The Rhoss THAITY 117 packaged heat pump chiller on the roof
​Klima-Therm has installed a high efficiency heat pump chiller at Salisbury District Hospital’s Breast Care Unit.

Developed by Rhoss with Padua University, the THAITY 117 system features a dual-purpose coil enabling it to be used as a water chiller during summer and water heater during winter. Linked to a compact Rhoss air handling unit (AHU), it delivers up to 16kW of cooling and 18kW of heating.

The packaged reversible DX heat pump is equipped with a heat recovery system based on a compact brazed plate heat exchanger for efficiency.

In cooling mode, the water coil operates at a temperature of 6deg C, and in heating mode at 45deg C. Fine control is provided by inverter-controlled scroll compressors and EC fans, which enable capacity to be turned down in small increments to 25 per cent of maximum output.
AHU air handling unit Rhoss compact Klima-Therm
The Rhoss AHU in the plant room
The unit’s adaptive control system continually monitors and evaluates the system’s thermal inertia in relation to set point and current load. The trend in water temperature is assessed against the fluctuating load, and parameters adjusted dynamically in real time.

As a result of the combined heat recovery system, inverter control and intelligent adaptive control logic, energy efficiency is very high, with an ESEER in cooling mode of 5.1.

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Quiet operation
The system overcomes the need to install a separate boiler and associated pipework, with just a simple connection required between the packaged heat pump and AHU.

It does not require refrigerant pipework to be installed within the building, overcoming any potential F-Gas concerns. Refrigerant charge (R410A) is extremely small, avoiding the mandatory requirement to carry out frequent system tests and reporting under F-Gas Regulations, thereby reducing ongoing maintenance costs.

Klima-Therm’s Andrew Latus, who headed the project, said: “Given the sensitive hospital location, noise was also an important issue. The system operates with very low noise levels due to the modulating compressors and fans, which under inverter control match output precisely to current load. As a result, the system operates at part-load for much of the time.”

When load requirements are low and there is a need for even quieter operation, such as at night-time, it is possible to limit noise levels to a pre-set level using an optional FDL accessory.

Paired with the Rhoss compact AHU, the heat pump system is linked to the existing Building Management System and caters for all of the building’s thermal requirements. Using a three-way diverter valve, the system can also be used to generate Domestic Hot Water.

Klima-Therm designed, supplied and installed the system, locating the AHU in an existing roof-top plant room and linking to the heat pump with connecting pipe work.

www.klima-therm.co.uk