2022-09-29-REC-min-att - Laserfiche WebLink

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_SED Associates Corp Consulting Engineers DESIGN MEMORANDUM DATE: September 13, 2022 TO: Chris Bouchard/Shawn Newell — Town of Lexington DPF FROM: Rick Calhoun — SED Associates Corp PROJECT: Lexington Town Pool SUBJECT: Domestic Water Replacement Options As requested, we have developed multiple options for the replacement of the oil -fired water heater at the above referenced location. In keeping with the Town's efforts to reduce its carbon footprint, all the options researched are electrically driven. A direct replacement oil -fired water heater was also researched for comparison. The heaters at this location are only operated between Memorial Day and Labor Day and are shut-off and drained down during the remainder the year. The provided spreadsheet titled "Revenue Attendance Summary 2021" indicates that there was a total 39,061 persons that utilized the aquatic venues offered by the town, which include the pool and the old reservoir. The pool had a total of 918.5 hour of operation for the same time period. The facility has a total of 18 showers. The existing electrical service consist of a 400 -amp 208/3/60 service from the utility company. This service feeds all the electrical equipment, including pool pumps and filtration system, lighting, etc. It was stated that the service is currently at a 300 -amp use level, leaving 100 amps available for additional electrical equipment. Assumptions Since there is no hot water use recording done at this location assumption need to be made to provide a basis for sizing of a new water heating system. If we assume all the people listed on the provided spreadsheet (39,061) utilize the pool and based on the total hours of operations (918.5), there is an average of 43 people per hour. Since not all people that use the pool utilize the shower facilities, we have assumed that 20 people in an hour with a maximum simultaneous operation of 6 showers with an average shower length of 5 minutes and a maximum of 110°F water temperature. Shower heads are rated for 1.5gpm mixed flow. With this combination of mixed water temperature and a storage of 140°F, 1.05 GPM of hot water is required. We have also assumed that the water heater should be able to recover itself in a 30 -minute period. Recovery is the amount of time required for the water heater to bring its storage volume back up to its storage temperature of 140°F. Demand 20 showers/hour* 1.05 GPM Hot Water * 5 Minutes = 105 GPH 105 GPH is the number that will be used to size the storage tank options for replacement water heaters.