Replacement is the key


St Clements Services Ltd, have replaced their old air conditioning with a heating / cooling City Multi Y Series, using the unique Mitsubishi Electric Replace Multi Technology.

With a total area of 275m2 on the second floor needing air conditioning to deliver a total cooling capacity of 30.2kW, a Replace Multi Y Series PUHY-P250YREM-A was specified to deliver heating or cooling with two PEFY-P100 ducted indoor units specified for two of the rooms and three PKFY wall mounted units for the others.

The Replace Multi system allowed Chillaire to keep the existing pipework and wiring and change the internal and external units, whilst removing the old, environmentally unfriendly R22 refrigerant and introducing an R407C system instead.

In addition to these environmental and energy efficient benefits, this meant that the building’s owners saved themselves over £3,800 by using Replace Multi instead of installing a completely new system.

Using the existing pipes also significantly reduced the time it took to get the system up and running and led to much less disruption for St Clements as the new system was installed in days instead of weeks.

To demonstrate the efficiency of the system over the older technology, the building was monitored between 23 May 2005 and 23 June last summer and during this time the air conditioning was in use for 481.75 hours.

The total energy cost to the consumer for this period was £56.37, which equates to an average running cost of just 12p per hour, or around 20p per m2 per month – approximately £2.46 per year on average.

In addition to this monitoring, the total power consumption of the outdoor unit was recorded every 15 minutes during the same period and the output was then compared to the outside air temperature provided by the MET office. What this has proved beyond doubt is that with a COP of 3.28, the new system is 28% more efficient that of the old one.

This is because when the temperature outside is low, the new unit does not consume as much power and reacts more quickly to changes in the outdoor temperature, with input increasing to compensate only when the outdoor temperature rises.

Further cost savings can now be achieved with flexible controls, which will monitor the complete system and ensure correct usage outside weekday office hours and at weekends, when little or no air conditioning is required.

Naturally, St Clements are delighted, not only with the savings on installation and running costs, but also with the high efficiency of the system which allows them to match current and future building regulations and also reduce other costs (such as gas boiler running time), in addition to providing much better overall room temperature control.

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