Common facility operational issues are often blamed on the dehumidifier

Spectator air comfort

Spectator air comfort complaints are common in facilities that host swim events. Swimmers feel comfortable in 27.7 C (82 F) space temperatures because they are wet and in bathing suits; however, fully clothed spectators will be uncomfortable at these conditions.

Facility managers that attempt to accommodate spectators by decreasing the space temperature and/or RH levels will trigger unintended consequences. If the dehumidification system was sized and designed to operate at swim event conditioning, deviating from its design temperature will increase the pool’s evaporation rate, which in turn increases energy use and RH. The system simply may not be able to maintain the swim event set points and the environment will be more humid and uncomfortable.

Natatoriums are typically designed to operate at a two-degree temperature differential (between space and water temperatures), such as 27.7 C (82 F) and 26.6 C (80 F), respectively. Therefore, lowering the space temperature by simply two degrees increases the load on the dehumidifier by 35 per cent. As a result, many of today’s natatoriums are being designed with separate systems for the spectator and pool areas.

Although both spaces co-exist, it is possible to create a small microclimate at a lower temperature and RH level in the spectator area. For older pools, retrofitting the spectator section with a separate dehumidifier and supply duct system can provide a resolution to complaints as well as possibly a quick payback in energy savings.

Dehumidifier operation

RH levels above 60 per cent are another indication the natatorium is not operating properly and typically points to two problems:

1. The facility is being operated at conditions for which it was not designed.
2. The dehumidifier is not operating optimally.

There are many instances where a facility operates its space and water temperatures differently from its original design. Facility managers should know the system’s design operating parameters and what type of dehumidifier/ventilation unit the facility has so operation expectations will be realistic. A traditional compressor-based dehumidifier should maintain a 60 per cent or lower RH and a stable space temperature year-round.

A ventilation-only style system, without compressors and a refrigeration cycle, should keep the space RH levels and temperature under control during cooler weather by utilizing drier, outdoor air. However, as outdoor temperatures get warmer, the ventilation-only system can only provide temperatures that are available outdoors.

Most designers typically adhere to the aforementioned two-degree operating differential recommendation. If engineering records or owner’s manuals are not available, the engineer (or company) of record that specified the dehumidifier should be able to provide details on the system installed and the operating conditions for which the facility was designed. Then, both space and water temperatures, as well as the RH can be confirmed with the readouts from the building automation system (BAS), or from the dehumidifier’s onboard or remote monitor.

Owners and operators are also recommended to take an active role in the design of a new facility to ensure the correct operating conditions are met. For instance, a swim event might demand a 26.6 C (80 F) and 25.5 C (78 F) air and water temperature differential, but a facility might also want the flexibility of providing elderly patrons with 31.1 C (88 F) water during an ‘Aqua Fit’ program. A dehumidifier sized and selected solely for family swimming in 27.7 C (82 F) and 26.6 C (80 F) space and water temperatures should not be expected to automatically have the capacity to accommodate the other two swimming environment extremes.

Natatorium dysfunctions can also be caused by a dehumidifier that is not operating up to the manufacturer’s specifications. Just like an air conditioner or any other mechanical equipment, dehumidifiers need annual servicing by a qualified contractor.

A slow degradation of space conditions can be caused by an improperly adjusted and/or underperforming system that is operating well outside its design parameters. In this regard, some manufacturers today offer dehumidifiers with web-based microprocessors, which relay operating parameters via the Internet to factory engineers for monitoring. This helps to ensure the dehumidifier performs as efficiently as possible, while optimum space conditions are maintained.

The bottom line for facility managers is to know the basics of natatorium design and dehumidification system operation in order to recognize and rectify problems sooner. The end result will be a more comfortable environment for patrons and a long-lasting facility with the lowest possible operating costs.

Ralph Kittler, P.Eng., is co-founder and vice-president of sales and marketing of Seresco USA in Decatur, Ga., a subsidiary of Seresco Technologies Inc., an Ottawa-based manufacturer of natatorium dehumidifiers. He has 23 years of experience in the heating, ventilation, and air conditioning (HVAC) industry and a degree in mechanical engineering from Lakehead University in Thunder Bay, Ont. Kittler recently produced a free ‘Professional Development Hour’ (PDH) video available at www.serescodehumidifiers.com that targets the continuing education requirements for engineers, but also serves as an invaluable primer of indoor pool design and operation basics for facility managers. He can be reached via e-mail at ralphkitter@serescodehumidifiers.com.