The University of New Mexico in Albuquerque has replaced the outdated hot water system in the L.F. Tow Diehm Athletic Facility.
The system in the facility, which has athletic offices, common areas, locker rooms for both home and visiting teams, and a weight room, was plagued by pump failures, electrical problems, and a leaking hot water storage tank.
“We were frequently called in after hours to tend to the old system,” says Richard Van Damme, HVAC master for the University of New Mexico. “At one point, we had even drained the 1,600 gallon storage tank for replacement, only to fill it again a few days later for game.”
Hot water was being supplied by two large, atmospheric volume water heaters with capacities of 490,000 BTUH each. The maintenance department had been pushing for replacement for a number of years. The cost of maintenance was rising, and outright failure was imminent.
Installing a similar storage tank would have required removing part of the roof the university said, so it also looked at tankless-style system options.
“There are short periods of high demand, with low or no demand otherwise,” said Jesse Hart, facilities engineer for the university’s facilities management department. The showers aren’t even used year-round, so the application lent itself perfectly to a high-efficiency, low-volume hot water system.”
The volume water heaters and storage tank were removed and 18 condensing, tankless water heaters from Navien were installed.
Water heaters were installed in two independent systems, one on either side of the mechanical room to serve each locker room.
Up to 16 units can be common vented, so only four roof penetrations were needed at the athletic facility.
When the new system was tested, every hot water fixture in the facility was opened for almost two hours. The units cascaded to meet demand, but never fired to 100%. According to Van Damme, full capacity was met and sustained while the systems are operating at 60% input.