Retrofitting HVAC Systems

by Sally Bouorm | August 1, 2014 10:05 am

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By Ralph Kittler, P.Eng.

Sooner or later an indoor pool facility will require a heating, ventilation, and air conditioning (HVAC) system retrofit. For many hotels, community, and school pools built in the 1980s and early 1990s this is happening now because their HVAC systems are close to the end of their typical lifecycle, which is approximately 15 to 25 years.

Pool operators with original equipment in facilities built during these time periods may want to start considering the idea of replacing their pool dehumidifier and/or ventilation unit. Even equipment dating back to the late 1990s is a candidate for full review in light of the energy-saving benefits today’s technology offers, as well as from the standpoint of annual maintenance costs associated with using older HVAC equipment.

Operational cost reductions and energy savings are the rewards of an indoor pool HVAC system retrofit; however, many facility operators discover that replacements in many of these facilities come along with logistical challenges. In fact, for many facilities, the most challenging retrofit problem can simply be getting the replacement unit into the building as few mechanical rooms are designed with retrofits in mind.

For example, many mechanical rooms might only have a 1.8- x 2.1-m (6- x 7-ft) double-door entrance on an interior wall or worse yet, a single 813-mm (32-in.) pedestrian door. Unfortunately, a dehumidifier or ventilation unit for a mid-sized community indoor pool can span up to 2.4 m (8 ft) wide with lengths of 3 m (10 ft) or more. Consequently, contractors are often forced to use a complicated knock-down approach when installing a replacement HVAC system. These units are designed specifically for these scenarios as they can be disassembled into multiple pieces and then reassembled inside the mechanical room. In terms of initial cost, these systems are much more expensive when compared to a standard, single-piece production unit.

Luckily, there are many options facility operators can consider should the mechanical room in their facility be inaccessible or provide little room to perform a complete retrofit. Each one has its own advantages as related to the given site conditions and retrofit budgets:

1. Remove door and bricks as needed around access openings to accommodate the replacement unit.
2. Have a replacement unit custom-built to fit through available access doors.
3. Open the roof to gain access to the mechanical room.
4. Knock-down the unit into smaller sections and reassemble as a complete unit inside the mechanical room.
5. Gut the unit on-site and assemble new components into the original dehumidifier’s shell.
6. Use several smaller modular units designed to fit through 813-mm (32-in.) doors that can be combined to provide the same operating capacity of the original, larger unit.

Sometimes retrofit selection committees only focus on custom equipment requirements and forget that a few site accommodations can dramatically reduce costs and simplify the project scope. Knocking out a few bricks around a doorway to expand it may cost only a few hundred dollars and could possibly save tens of thousands of dollars by avoiding the need to custom-build an HVAC system simply to fit through a small doorway. Typically, the bigger the opening is, the installation becomes easier and less costly.

Assembling units inside a mechanical room can be challenging. These systems are quite complex and the reassembly requires care and refrigeration experience. Manufacturers often recommend the units designed for disassembly be shipped to the jobsite as an assembled system, and then broken-down into more than three sections. It is easier for contractors to reassemble a system if they disassemble it. Likewise, the manufacturer should also be privy to the site’s access limitations so they can design a unit with the fewest possible sections.

The weight of each section is also an important consideration. A narrow access way may only allow one or two riggers and a handcart to fit, which would require lightweight loads to manoeuvre. Therefore, it is important to find a consulting engineer, contractor, and a manufacturer that can explore all the aforementioned alternatives and help choose the most feasible method.

Kanata retrofits its wave pool

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The $500,000 renovation of a 25-year-old conventional indoor public recreation centre in Ottawa—now called the Kanata Leisure and Fitness Centre—is a good example of the challenges indoor pool facilities face when fitting new equipment into original mechanical rooms.

The facility’s mechanical room had limited access; there were no shipping doors or adjacent space for expansion, yet the replacement system had to be larger due to the following factors:

• it was a single unit replacing two units;
• it incorporated more technologies such as heat recovery from exhaust and air conditioning, which the previous system did not have; and
• it had more dehumidification capacity because the original units struggled at times to accommodate the evaporative rates produced by the facility’s unique array of water features.

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To meet this challenge, a larger 2.6-m (8.5-ft) high x 3-m (10-ft) wide x 7.3-m (24-ft) long custom-manufactured HVAC system was specified to save the facility thousands of dollars with respect to installation and labour costs, not to mention facility downtime. After scouting the site, engineers determined an outdoor air louver, part of a large mezzanine-level mechanical room’s exterior wall, would provide the most economical access point to get the system into the building. The manufacturer also custom-built the unit for disassembly into three, 2.4-m (8-ft) long sections for shipping, but only after the factory assembled and tested the unit under simulated natatorium operating conditions. The mechanical contractor on the project rigged the HVAC system’s three sections through the outdoor air louver, which was expanded by 2.7 x 3 m (9.1 x 9.8 ft) to provide additional space, then reassembled and installed inside the small mechanical room. The expanded louver opening was then refitted for a new outdoor air damper/louver. While reconfiguring walls or roofs can add
expense to a retrofit, the enlarged access was beneficial for complying with American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standard-62[4] outdoor air rates, which have increased since the facility was originally constructed in 1986.

Building a ship in a bottle    

There has been an influx of indoor pool facilities with HVAC equipment (circa 1980s) in need of replacement over the last few years. Some of these facilities have also proved challenging due to the mechanical room’s size limitations, location, or accessibility.

One difficult retrofit completed by a Mississauga, Ont., manufacturer’s representative/contractor  was a 30-year-old, 279-m² (3000-sf), suburban Toronto municipal pool with an aged dehumidifier located in a second floor concrete bunker with no external access doors. Making matters worse was a 15-step access stairwell that leads to the mechanical room’s 863-mm (34-in.) wide pedestrian door.

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One option was cutting into the building’s roof and the mechanical room’s ceiling to accommodate a drop in placement of the 1.8-m (6-ft) high x 1.8-m (6-ft) wide x 4.8-m (16-ft) long unit with a crane. The job estimate for opening and closing the access holes was $40,000, which the city declined. Another option was putting the new unit on the roof; however, that would require another budget-busting process that would have included structural roof support reinforcement, connecting ductwork, new utility runs, and an improved roof access for future maintenance.

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The chosen alternative was disassembling the unit at the manufacturer’s factory and shipping it in five pieces. Once on-site, the five sections were further broken-down to reduce weight and make it possible to fit the sections through the narrow door and stairway. Once inside the mechanical room, the sections were reassembled.

As per the recommendation of the project’s consulting engineer, the contractor worked with the manufacturer to pre-plan site condition limitations, turning radiuses, duct connections, obstructions, piping connections, and other variables the firm anticipated based on similar challenges the company experienced in the past. Co-ordination with manufacturers is important, because not all companies will accept the engineering restraints required with units planned for disassembly and reassembly on-site.

The same contractor also tackled another challenging project, but with a considerably larger dehumidifier unit that was 3.3-m (11-ft) high x 3-m (10-ft) wide x 10-m (33-ft) long. This system—designed for a Toronto suburb jobsite—was to replace an HVAC system installed during the 1990s. To complete this project, the unit was delivered in 150 sequentially-numbered and identified pieces to fit through the 2415-m² (26,000-sf) facility’s 1016-mm (40-in.) wide hallway that led to a restricted 70-m² (750-sf) mechanical room.

Typically, the manufacturer would assemble a conventional dehumidifier with welds; however, this project’s many sections were engineered to be bolted together on-site. The contractor then set-up the mechanical room like a mini-factory, complete with chain lifts for positioning heavy components in place and welding stations. Assembly required staging six technicians, each working 12 hours per day on their own specialty in frame/enclosures, piping, and electrical.

Additional alternatives

New technologies in the HVAC industry, such as modular units, may also help ease equipment installations in smaller mechanical rooms with limited access. Manufacturers have recently developed smaller modular units that can fit through 813-mm (32-in.) doorways, which enables contractors to install a complete unit that is capable of operating at the same capacity of a single, larger system. Essentially, they are separate units but each has a compressor, supply air fans, etc. They can also function together or independently in a staged operation, which can provide energy and redundancy benefits.

This method of installation was used in a retrofit project at the Niles Family Fitness Center—a $14-million, 9290-m² (100,000-sf) facility built in Illinois in the 1990s. The facility’s original dehumidifier was fairly large and controlled 131.5 kg (290 lbs) of moisture per hour in the building’s 743-m² (8000-sf) wing which contained the natatorium’s 418-m² (4500-sf) pool. The consulting engineer opted to stack smaller dehumidifiers designed specifically for modular applications.

Another option is to gut the original unit and install new components, such as compressors, coils, and fans, into the existing shell. This retrofit method was recently used at Stevenson High School (also in Illinois) which hosts various state swim meets at its eight-lane, 50-m (164-ft) pool. The facility is also capable of holding up to 1,000 spectators. The retrofit contractor was challenged with the size of the dehumidifier and its replacement, thus it chose to use the existing shell and build energy-efficient components into it.

Planning for a retrofit during design

Foresight is important when constructing natatoriums and their necessary mechanical rooms as it will help save money in retrofit costs later on. Planning for something that will hopefully only happen in 25 years is not typically at the top of anyone’s priority list, but all equipment will eventually need to be replaced. A little planning in the beginning could generate substantial savings down the road.

Mechanical room space is another restrictive factor. With the high costs of construction (based on square footage), rooms that do not produce revenue, e.g. a mechanical room, are not often built as large as the design engineer would like. A small, restrictive mechanical room will not only create HVAC retrofit challenges later on, but could also potentially affect routine service and maintenance capabilities. One compromise that should never be considered is reducing service access. An inaccessible unit is difficult to maintain and adjust, which will negatively affect performance and ultimately the system’s life expectancy.

Installing HVAC equipment on the rooftop of a facility would be a good consideration in light of the aforementioned mechanical room challenges; however, it comes down to a trade-off between saving indoor mechanical room space, which can range between $100 to $225 per square foot, and the benefits of installing the equipment inside the facility. For example, rooftop locations cannot always be hidden from view to maintain the building’s architectural esthetics or structural integrity. For instance, a gable-style roof design with no flat areas for mounting a large HVAC system makes rooftop installations improbable. Further, the location might also be more remote from the pool, which will increase installation costs. Rooftop units are also more susceptible to heat loss and wear and tear from outdoor elements than their indoor counterparts. When rooftop equipment has poor access or is located in harsh climates, many times their maintenance is more neglected than indoor systems.

Using retrofits to reduce operational costs

Existing indoor pool HVAC systems do not have to permanently breakdown before considering replacement. Long before its useful lifecycle is over, an HVAC system may show signs of inefficiency or excessive maintenance costs.

Inefficiency can often be overlooked because it is typically a slow degradation that goes unnoticed between service calls. However, comparing same-month utility bills may help spot systems that are not working up to their expected efficiencies. Indoor air quality (IAQ) deficiencies may also gradually degrade unnoticed.

Numerous maintenance or service calls throughout the year could also be a red flag for replacement consideration as well as refrigerant leaks. Leaks can be lethal to budgets, especially systems using R-22 refrigerant. This refrigerant was a popular choice in the 1980s and 1990s, which has dramatically escalated in price due to a recent production ban by government agencies. Taking this into consideration, replacing an older unit that is leaking or breaking down two or three times per year might deliver a fairly short payback via reduced repair costs and increased efficiency.

A recent development, which reduces the amount of refrigerant used by today’s newer HVAC systems by as much as 85 per cent, is another advantage manufacturers have provided to indoor pool operators against the environmental impact and cost liabilities of using banned refrigerants.  The use of glycol in some of the largest parts of the dehumidifier reduces its dependency on refrigerants. Glycol has been used in this manner in other markets for decades. It is 90 to 95 per cent cheaper and more environmentally friendly than hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC) refrigerants.

Another consideration may be the need to replace the refrigeration piping, which is typical in split system designs where hot gas refrigerant is piped to outdoor condensers for heat rejection. New refrigerants can operate at double the pressure of what they are replacing. Consequently, existing piping is not typically suitable for reuse and should be replaced in a retrofit project. When glycol is used to reject heat generated by the system outdoors to dry coolers, polyvinyl chloride (PVC) piping—rather than copper— is used and most of the system fill comes from the water tap with some glycol mixed in.

Some ductwork modifications connecting the replacement unit to the natatorium’s existing air distribution network will likely be required; however, the majority of the air distribution system can be reused if it previously provided adequate IAQ and is still in decent shape. Additional power might be required if the original design’s operating conditions have been changed, or if more water features have been added, which increases the dehumidifier’s humidity load.

There are hundreds of indoor pool systems in Canada that could benefit from an HVAC upgrade. While indoor pool operators may look at a dehumidifier or ventilation system retrofit as an overwhelming and costly ordeal, the right team could deliver the best possible resolution with minimum disruptions and a quick turnaround. Once the upgrade is complete, the facility should benefit from better IAQ and comfort, while also operate more efficiently. Not only does this translate into reduced energy and maintenance costs, but also increased revenue from more attendance.

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 and outdoor air ventilation only systems (OAVOS). He has 25 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[7], which 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[8].

Source URL: https://www.poolspamarketing.com/trade/newer-technology-can-save-money-but-is-there-room-for-installation/

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