L.F. “TOW” DIEHM ATHLETIC FACILITY, UNIVERSITY OF NEW MEXICO, ALBUQUERQUE
RETROFIT TEAM
WATER HEATER INSTALLER: Futures Mechanical
PLUMBING REPRESENTATIVE: RepNet
MATERIALS
Named for Tow Diehm, who served as UNM’s athletics trainer for 31 years, the athletic facility includes offices, common areas, locker rooms for home and visiting teams, and a weight room, all of which underwent an $800,000 renovation in 2014.
However, that renovation didn’t address ongoing problems with the facility’s domestic hot-water system, which provides hot water to all fixtures within the building, including the home and visitor locker-room showers. During the past few years, nonstop pump failures, electrical problems and a leaking hot-water storage tank plagued maintenance crews. Inevitably, these problems surfaced at the worst times, like game day. Hot water was being supplied by two large, atmospheric-volume water heaters with capacities of 490,000 Btuh each.
“When we received a work order to replace the failing system, we evaluated a straight, in-kind replacement with standard-efficiency water heaters. Installing a similar storage tank would’ve required removing part of the roof. We also looked at tankless-style system options. Energy savings was a big consideration, as was redundancy and serviceability,” notes Jesse Hart, facilities engineer for UNM’s facilities management department. UNM’s facilities team looked at various tankless products and contacted their local Navien representative, Jordan Mahboub. Mahboub and Hart worked closely with Navien sales engineers to create a design based on the peak hot-water demand at the facility: 82 gallons per minute at 120 F. The university wanted the ability to meet peak demand with one or two units offline.
Once the design was approved, the volume water heaters and storage tank were removed and 18 Navien NPE-240S condensing, tankless water heaters were installed. The NPE-240S is a 199,900 Btuh condensing, wall-hung water heater that features dual stainless-steel heat exchangers, a 10-to-1 turndown ratio and efficiencies up to 0.97 UEF.
Water heaters were installed in two independent systems, one on either side of the mechanical room to serve each locker room. Navien’s Ready-Link manifold and rack system was used to simplify the installation and save space. The manifold system provides everything required for a multi-unit installation, including manifolds for water and gas, racks for floor mounting, valves, connections and flex lines. Up to 16 NPE-240 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 while the systems operated at 60 percent input, according to the facilities team. The entire project took three months during the 2018 summer break and was completed just in time for football season. The facilities department has been so impressed with the units that it has decided to use Navien systems in other locations across campus.
TANKLESS WATER HEATER MANUFACTURER: Navien
PHOTO: NAVIEN