Client name: University of Limerick
Location : Limerick
Type of installation : Swimming Pool
AHU frames - constructed from pentapost aluminium, anodised for protection in the chlorinated environment
LPHW heating coils - copper tube with copper fins, supplied from the factory acrylic coated with a stainless steel casing rated at 460kW
Mixing dampers - anodised aluminium with individual seals, interconnected by moulded polymer gear mechanisms
Filtration - air was filtered on the supply air side using rigid bag filters, which contain no ferrous components.
A closed cell foam seal was used to seal the filters to the support frame, which was manufactured from plastic extrusion with stainless steel clips.
Anti-vibration - achieved by means of spring and flexible duct connection
Passive heat recovery - provided by a Polycarbonate double plate heat exchanger
Motor and fan arrangements - EFF 01 class F classification electric motors featuring tropicalised windings with integral thermistors were selected for their efficiency and suitability for VSD. The complete fan assembly was factory epoxy painted
Internal AHU construction - manufactured from galvanised steel, which was epoxy painted and applied by hand.
After the surfaces had been prepared by detergent and degreased, epoxy primer was applied at a dry film thickness of 40 microns. A secondary intermediate epoxy coat at 100 microns was then applied and allowed to dry under atmospheric conditions, before a polyurethane acrylic topcoat at 35 microns dry film thickness was applied.
The AHU's were supplied to site completely pre-wired. Jet AHU designed and programmed a controls strategy that featured a digital outstation positioned within a controls enclosure on the air handling units, and all actuators and sensors are wired directly to it.
Since the fresh air requirement varies throughout the day, Jet AHU designs air handling units to provide a level of fresh air that is capable of being adapted to meet changing conditions. As a result, fresh air levels can either be fully automatic or determined by the pool owner.
Avoiding condensation in the swimming pool hall is of paramount importance if the structure of the building is to be properly protected. This is achieved by maintaining the humidity at a level that prevents excessive evaporation from the pool, whilst preserving a comfortable environment for bathers. Allowing the humidity to rise in line with the increase in ambient temperature not only keeps fresh air requirements to a minimum, but also drives running costs down.
Jet AHU engineers its units to continually vary the humidity of the building in accordance with outside temperature changes and adheres to the following principles when developing AHU specifications:
Units must provide high quality indoor atmospheric conditions
AHU's must be reliable and economic to operate
For optimum performance AHU's must be energy-efficient and easily maintained
A totally integrated package is easy and quick to install
Units are designed with the aid of modern software and construction technologies, to increase unit efficiency and reduce operating costs.
Ensuring optimum operating efficiencies
Jet AHU's air handling solutions combine a number of energy saving techniques to reduce the end users overall energy bill. A plate heat exchanger recovers the heat in the outgoing exhaust air. This is a passive heat exchanger, as there is no energy input to this unit.
Instead, it picks up the heat in the exhaust air stream and transfers it into series of aluminium plates. Typical efficiencies for these exchangers are 60%, so if the exhaust air is being output at 30 degrees C and fresh air is entering the unit at 0 degrees C, Jet AHU's air handling system will heat the air to 18 degrees C. To reduce the electrical energy consumption Jet AHU selects high efficiency fans with backward curved blades, as these give an extra 10% saving over forward curved fans.
Increased system performance and monitoring is achieved by an integral controls package, which also aids swift unit installation. Sensors mounted in the return air chamber send the temperature and humidity reading back to the controller every few seconds. Using this information, the controller determines the amount of air and heat required, along with the degree of recirculation that can be permitted. Precise control is thus achieved over the internal conditions within the pool hall, while the AHU is not working any harder than necessary, thereby keeping running costs to a minimum.
Jet AHU specifies swimming pool units with frequency inverters to ensure improved air volume control. Frequency inverters alter the frequency of the electrical supply to the motor, which reduces the speed of the motor and, in turn, the fan speed. The slower the fan runs, the lower the air volume achieved.
By controlling the frequency inverters it is possible to gain precise control of the air volume. This control over air volume means the exact amount of fresh air required can be introduced as required, helping to minimise the heating load.
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