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HomeMy WebLinkAbout11 17 08_Swim Center Air Handler Replacement Commission Memorandum REPORT TO: Honorable Mayor and City Commission FROM: Ron Dingman, Park and Recreation Director Chris Kukulski, City Manager SUBJECT: Swim Center Air Handler Replacement MEETING DATE: November 17, 2008 RECOMMENDATION: Direct staff to complete the design, engineering and bidding for a new air handling unit for the Swim Center, and to bring back to the Commission the necessary budget amendment. BACKGROUND: The Swim Center Air Handler Unit, that maintains the air environment within the building, is in need of immediate replacement. The unit’s motor has failed on at least 2 separate occasions, requiring a maintenance company to hard wire the motor past the controls and to the fuse. One of the failures caused the pool to be closed for 4 hours due to poor visibility, which impairs lifeguard vision, and air quality. The American Society of Heating, Refrigeration, and Air Conditioning, ASHRAE, sets standards for Aquatic Facility air quality. Their established standards require an air exchange of at least 6- 8 per hour for our pool. Our system exchanges only 2.27 per hour at full potential. The unit is currently running at 80% capacity, or 1.82 exchanges per hour. The US Aquatics July 2008 Survey Report addresses the air quality in the building as a major issue and offers 3 options to solve the problem. Option 1 recommends replacement of the existing Air Handler unit. Options 2 and 3 are no longer viable options because the existing system is failing. A new Air Handler system would involve engineering a new duct system, installing the duct system, and ordering and installing a new Air Handler unit. Once ordered, it will take 3-5 294 months to build and ship the air handler. The earliest we can expect the new unit to be installed is April 2009. FISCAL EFFECTS: Direction to move forward will ultimately commit the City to spend an estimated $215,000 on the design, engineering, purchase and installation of the new air handling unit and duct work. Design and engineering will begin immediately; order of the air handler itself will require a formal bid award. ESTIMATED COSTS Design & Engineering $20,000 Duct Work $45,000 Air Handler $150,000 TOTAL $215,000 The primary source of funding for this project would be the City’s General Fund. A budget amendment would be made after bids for the Air Handler are received. If this entire project were funded from General Fund reserves ($215,000), the reserve would decrease from an estimated $4,135,000 to $3,920,000 at the end of the fiscal year; representing 18.8% of FY09 Revenues. ALTERNATIVES: As suggested by the City Commission. Respectfully submitted, _________________________________ ____________________________ Ron Dingman, Parks and Recreation Director Chris A. Kukulski, City Manager Attachments: • Page 3 of Swim Center Survey Report • Sections 4-6: Morrison-Maierle Survey Report on ventilation and dehumidification systems • Photos of existing air handler and vapor cloud 295 Report compiled on 11/10/08 296 SUMMARY A survey of the Bozeman Swim Center aquatic facilities was conducted on May 29, 2008 by Tom Schaffer & Nick Nowacki of USAquatics, with the assistance of facility personnel. At the time of the survey, the facility was in working condition and was fully open for use. The facility appeared to be functioning properly, and considering its age, was found to be in excellent condition. The facility is maintained very well and based on our observations, the staff has done a very thorough and excellent job in organizing and maintaining facility records and documentation. In addition, based on our discussions with facility personnel, the extent of staff training is exceptional and exceeds that which is required. With respect to operation, the facility is very organized and well managed. The purpose of our survey was to identify any major areas of concern with the facility and to perform a full code review, identifying deficient areas, no matter how tedious. Our intent was to provide you with a concise summary of all facility deficiencies for your analysis. This report identifies issues/problems/negatives and should not be viewed as an overall state of the facility. As stated earlier, this facility is in excellent condition and is very well maintained. The overall structural state of the building, pool, and decking appears to be in good condition. The ceramic tile decking surface is in good condition and the pool has a near brand new finish. If proper maintenance of the facility continues to occur and systems are updated as they become outdated, this facility could easily last 30+ more years. One of the major issues with the facility is the natatorium air environment. At the time of our visit, the air in the natatorium was very humid and the presence of combined chlorine was evident through smell and reaction to our eyes. We performed some rough calculations of the air handling capacity of the existing facility and roughly determined that the turnover rate of the air in the natatorium was approximately 40% of that required by general standards. As a result of this and the high humidity levels, we contracted Morrison-Maierle Inc. to perform a survey/assessment of the facility with respect to the natatorium ventilation and dehumidification systems. Their report and recommendations is provided in Sections 4-6. We are in agreement with the information and conclusions reached within their report, and recommend Option 1 as presented. This appears to be the most economical and efficient option to alleviate humidity and combined chlorine concerns in the existing natatorium. Option 1 will eliminate concerns with equipment maintenance and replacement and provide the most efficient and effective air handling, dehumidification, and heating. In addition to our site survey, we also requested past water testing logs for (3) summer months and (1) winter month. Review of these logs indicated a consistent reading of combined chlorine near 2.0 ppm, during both summer and winter. The Montana pool code requires that a combined chlorine reading of 0.5 ppm or greater requires super-chlorination. Based on the log sheets and continuous combined chlorine readings over 0.5 ppm, the pool has not been meeting health code requirements or generally recommended levels. You have an ongoing high combined chlorine situation that is a major concern to us. This could be a result of improper or absence of super-chlorination. Combined chlorine is a nuisance due its strong odor, but it can also become a safety issue as there is the potential for reaction with the eyes, nose, sking, lungs, etc. Based on this high combined chlorine and after review of the water testing logs, we are recommending the installation of an ultra violet (UV) system. A UV system combined with the replacement of the air handling unit (as recommended in the HVAC Option 1) will work together to eliminate combined chlorine issues. Although each option, if installed separately, will help reduce combined chlorine, we believe that installation/replacement of both the UV system and air handling unit is necessary to full alleviate any issues with combined chlorine. 297 SECTION 4 EXECUTIVE SUMMARY (HVAC) STATEMENT OF UNDERSTANDING It is our understanding that USAquatics Inc. is conducting a facility assessment of the Bozeman Swim Center in order to provide the City of Bozeman a comprehensive report of the current state of the facility, problem areas, recommendations and cost estimates. One area of concern preliminarily defined by USAquatics is the indoor air quality and mechanical system function in the natatorium. The goal is to provide USAquatics and in turn the City of Bozeman with a focused report on the mechanical heating, ventilation and dehumidification systems of the natatorium. This report includes analysis of the existing mechanical equipment, a statement of the problem areas, recommendations and options for repair or replacement of mechanical systems, and a cost estimate for those options. STUDY APPROACH The study approach primarily consisted of a physical assessment of the existing pieces of mechanical equipment, review of original design drawings and discussion with facility personnel. SCOPE OF STUDY The scope of this study covers the following mechanical systems - Primary air handling unit (AHU) for the natatorium - also known as “Henry” - Radiant heating system - Dehumidification equipment STUDY CRITERIA The criteria used in our assessment includes: - ASHRAE standards. - 2006 International Mechanical Code INTENT OF REPORT Provide recommendations for repair and replacement of existing mechanical systems in an effort to meet current codes and standards, provide user comfort, and increased efficiency resulting lower energy bills for the Bozeman Swim Center. 298 SUMMARY A survey of the Bozeman Swim Center mechanical equipment was conducted on June 26, 2008 by Jennifer Burgett of Morrison-Maierle, Inc with the help of Swim Center personnel. The facility personnel have maintained the mechanical systems very well. Documentation was provided including past studies, energy audits, equipment information and maintenance records. The mechanical systems that serve the natatorium include six refrigerant-type dehumidifiers located around the perimeter of the pool, a Co-Ray-Vac gas fired radiant system that runs the length of the pool on the east side, and a large air handling/ventilation unit located at the exterior of the building on the east side. The survey focused on these three main mechanical systems. Dehumidification Equipment: Six Desert Aire (Model EHCC-500) dehumidifiers were installed in 1983 around the perimeter of the pool to reduce the quantity of outside air ventilation required for humidity control. Since the 1983 installation, the system has been completely replaced one dehumidifier at a time. Each new dehumidification unit is a Desert Aire Model IH-500. The oldest unit was installed in 1998 and is the west middle unit. The east middle unit was installed in 1999. The southwest unit was installed in 2000. The northeast unit was installed in 2001. The southeast unit was installed in 2002. The newest unit is in the northwest corner of the natatorium and was installed in 2004. These dehumidifiers are refrigerant type (R-22) units that remove moisture from the air by cooling and then reheating the air. The heat from the refrigeration compressor is also rejected to the natatorium. This set up works well in the winter because the rejected heat helps to warm the natatorium. Two of the six dehumidifiers are turned off in the summer because the added heat is too great to maintain comfort. All of the dehumidification units are electrically driven with 208 volt, 3-phase power to each one. A power surge at the end of May has disabled the newest unit in the northwest corner. The motor has burned out and must be replaced if all six dehumidifiers are to remain in operation. Maintenance records indicate that contractors are called to repair one or more of the dehumidification units approximately 3 times per year. Radiant Heating System (Co-Ray-Vac): The Co-Ray-Vac radiant heating system was installed in 1985 because one of the originally installed, roof-mounted air handlers was not functioning and not able to be repaired. The intent was to supply heat to the deck and pool area lost by the non-functioning AHU. This radiant heating system is capable of supplying 280,000 BTU per hour of heat to the natatorium if it is operating at full capacity. The Co-Ray- Vac system is operating well. It has been serviced a couple of times since it’s installation in 1985. Another burner was added in the 90’s to give the system a more uniform heat over the entire length of the radiant tube. Air Handling Unit (Henry): The main air-handling unit (AHU) is an exterior packaged, gas fired Pace unit. It was installed in approximately 1987-1988 to replace the original (2) air handler, roof-mounted system installed in 1975. The AHU is intended to supply the natatorium with outside, heated air and to return air from the natatorium back to the air handler where it is exhausted to the atmosphere. The air-handling unit was designed to supply 10,600 cubic feet per minute (cfm) of conditioned air into the natatorium and exhaust 11,000 cfm. Having the exhaust greater than the supply yields a slight negative pressure to the room. This negative pressure is in accordance with the recommendations of ASHRAE A4.6 as it limits 299 chloramine odor migration throughout the rest of the swim center. The AHU has been serviced many times since its installation. A gas-fired Modine unit heater was installed in 1996 to pre-heat the outside air when the temperature dropped below 0 degrees F. A hood was also added over the intake louver in 1998 to prevent snow from entering the air intake louver and causing the filters to clog thus shutting down the unit. The Pace air handling unit supplies all of the ventilation for the natatorium. If the unit is operating at full capacity, the ventilation rate is 2.27 air changes per hour. ASHRAE A4.6 recommends pools with no spectator areas to have 4 to 6 air changes per hour and pools with spectator areas to have 6 to 8 air changes per hour. The Bozeman Swim Center appears to fall somewhere in the middle of these two types of pools. Bleachers are set up to for a viewing area, however, the Swim Center personnel have stated that large competitions that would fill the bleachers only happen three to four times per year. 300 SECTION 5 ANALYSES OF EXISTING CONDITIONS (HVAC) AREAS OF CONCERN Generally, the mechanical systems are in fairly good working order. As previously stated, the Swim Center staff has done a great job keeping the various systems in operation. Morrison-Maierle, Inc. has identified the following areas of concern with the three main mechanical systems. Options and recommendations for repair, renovation, or replacement for the overall mechanical system are contained in Section 3. Air Handling Unit (Henry) 1. The existing air-handling unit was installed in 1987. Pace, the manufacturer of the AHU, went out of business in 1997. This is not a major concern as Air Controls of Bozeman is familiar with the system and has serviced it since its installation. However, it does not modulate between high and low fan speed anymore and has been over ridden to be on high fan speed all the time. This will expedite the lifespan of the AHU and as it continues to age, finding parts for repair and replacement may become problematic. 2. The natatorium requires 28,000 cfm to achieve 6 air changes per hour. As early stated, the natatorium is only receiving 2.27 air changes per hour if it is running at 100% of its capacity. Given the extensive repair work that has been done on the air handler, Morrison-Maierle, Inc. does not believe it is actually producing the 10,600 cfm listed on its supply fan tag. Most likely, the air handler is providing 60 to 70 percent of its original design and installation specifications. This is a major issue because the AHU is the only source of ventilation for the natatorium and it is undersized by current codes and recommendations, even if it is operating at 100% of its stated capacity. As a result of the low level of ventilation, the Bozeman Swim Center is suffering from diminished indoor air quality for patrons and staff and accelerated deterioration of metal ductwork. Because of the low venting levels the Swim Center is also vulnerable to deterioration of wood and concrete building materials, increased occurrence of mold and mildew and damaged insulation. 3. The outside air delivered by the air handler to the natatorium is required (by ASHRAE Standard 62.1) to be 6,700 cfm. This is roughly 24% of the total 28,000 cfm required to achieve 6 air changes per hour in the natatorium space. The air handler appears to be a 100% outside air unit, thus, 10,600 cfm of outside air is being delivered to the natatorium if the air handler is running at 100% of its capacity. Thus, the natatorium is receiving the required amount of outside air even if it is deficient of the adequate ventilation. 4. An abnormality with the power (power surge) occurred on May 24, 2008. At this time, Air Controls of Bozeman was called to service the main air-handler because it did not restart after the power surge. They recommended replacement of the high/low motor controller and motor controller switch for the exhaust fan. Air controls also indicated that the supply fan controls are warn and their enclosures are rusty. Radiant Heating System (Co-Ray-Vac) 1. The radiant heating system appears to be in good working order. The Swim Center personnel 301 have not reported any problems with the unit, but did report that the system is very necessary in the winter to provide supplemental heat. Dehumidification – Six Units Located in the Natatorium 1. Five of the six dehumidifiers function and do not seem to have any major problems. The dehumidifier in the northwest corner of the natatorium was affected by the power surge on May 24, 2008. As a result of the surge the northwest dehumidifier would not restart. Air controls found the motor to be seized and the unit would need to be replaced if it is to be kept operational. 2. The heat rejected by the dehumidification units into the space is too great to keep them all operating in the summer, thus higher humidity occurs in the spring and summer. 3. The dehumidifiers need to be repaired and maintained often to keep them in operation. After looking through the maintenance records, it appears that a contractor is called approximately 3 times per year to service one or more of the dehumidifiers. 302 SECTION 6 COST ESTIMATES (HVAC) OPTION 1 – Replace the Air Handling Unit COST Option 1, Replacing the Air Handling Unit, is the best option for overall, long-term building health. It will address humidity, ventilation and heating issues currently experienced by the swim center. It will also reduce potential problems with mold, mildew and condensation that will harm the building’s structure and create indoor air problems for swimmers and employees. Unfortunately, Option 1 is also the most expensive, requiring a large system replacement. The recommended unit would be an energy recovery ventilator, refrigeration based dehumidification system with gas heat similar to the one installed in the Missoula Aquatic Center in 2005-2006. This system would provide heating, dehumidification and ventilation. Two exhaust fans are recommended directly above the pool on the high point of the Swim Center roof for added exhaust to make the space negative and allow for a complete system purge. In this case the existing dehumidifiers and the radiant system would not be necessary but should be kept in place as long as they are in working order to provide heat and dehumidification on extremely humid or cold days. New Air Handler Heat Recovery Unit (28,000 cfm) $160,000.00 Ductwork Renovation $ 20,000.00 Total $183,000.00 Exhaust Fans (2 at 1,400 cfm each) $ 3,000.00 OPTION 2 – Supplement the Existing Air Handling System COST Option 2 entails keeping the existing mechanical equipment in service as long as possible and adding an air handler/heat recovery unit, similar to the one outlined in Option 1, capable of 14,000 cfm (half of what the facility would require for 6 air changes per hour). If the existing air handler is capable of supplying approximately 10,000 cfm that would bring the total to 24,000 cfm. 24,000 cfm equates to 5 air changes per hour which would double the current ventilation and be within the ASHRAE recommended levels of 4 to 6 air changes per hour for a pool with no spectators. A test and balance report would be necessary to determine exactly how much air the existing air handler supplies and exhausts. The existing air handler should be maintained and repaired to ensure it is operating as well as possible. Exhaust fans should be installed for this option too to allow purging and extra exhaust over the pool. This option would drastically increase the overall indoor air quality and provide a lower first cost to the Swim Center. This would leave the possibility of adding a second phase where a duplicate air handler (14,000 cfm) could be added to replace the existing AHU and increase the ventilation to 6 air changes per hour. If a second phase was executed to bring the Swim Center up to optimum conditions as was outlined in Option 1, the overall cost of both phases would be greater than that of Option 1. 303 Test and Balance Report $ 2,500.00 Existing Equipment Maintenance $ 2,500.00 New Air Handler/Heat Recovery Unit (14,000 cfm) $80,000.00 New and Renovated Duct Work $20,000.00 Total $108,000.00 Exhaust Fans (2 at 1,400 cfm each) $ 3,000.00 Future phase: New Air Handler (14,000 cfm) $ 90,000.00 Total $100,000.00 Renovate/Replace old ductwork $ 10,000.00 OPTION 3 – Provide Added Ventilation COST Option 3 would be to keep the existing mechanical equipment in operation, including replacing the dehumidification unit that is currently not functioning, and add exhaust fans and louvers to provide the ventilation necessary to accommodate at least 4 air changes per hour (minimum allowed by ASHRAE and the International Mechanical Code) in the natatorium. Gas unit heaters would be required to provide extra heat to make up for ventilating with outside air in the winter. The controls would have to be modified to tie the Co-Ray-Vac system, the existing air handler, the dehumidifier and the new louvers, exhaust fans and unit heaters together so that while the new fans are pulling air through the louvers, a comfortable temperature is maintained in the natatorium during colder months. A test and balance report would have to be executed in this phase as well to determine the actual amount of air being supplied and exhausted by the air handler. This option will provide needed ventilation and has the lowest first cost. However, it would add several other pieces of mechanical equipment to an already complex system of mechanical equipment. And although this system is the most cost effective in the short term, it is the least energy efficient and it relies on keeping the existing equipment in operation which by all accounts has been challenging over the past ten years. Test and Balance Report $ 2,500.00 Maintenance and Repairs to Existing Air Handler $ 2,500.00 Ductwork Maintenance (replacing corroded pieces) $ 5,000.00 New Gas Fired Unit Heaters $ 5,000.00 New Desert Aire Dehumidification Unit $15,000.00 Exhaust Fans (5 at 2000 cfm each) $ 8,000.00 Louvers (2 at 5’x5’) $ 5,000.00 304 Total $53,000.00 Additional Controls $10,000.00 305 306