Culver Cove, an 80-unit condo complex located on Lake Maxinkuckee near Culver, Ind., had a dilemma on its hands. The multifamily facility originally had six 100-gal., commercial tank-type water heaters in three utility rooms that supplied hot water. As the original units began breaking down, Culver City Executive Director Rich West was looking or a more efficient hot-water system to reduce energy costs.
West found his answer working with Mike Lambert of Elkart, Ind.-based Mid-City Supply and Clark Boyles of Indianapolis, Ind.-based PM & Associates (pme’s 2015 Manufacturers Rep of the Year award winner), the Navien Northern Indiana distributor and manufacturers representative respectively. Together they recommended installation of five cascaded Navien NPE-240 units for about 24 to 26 units from one- to three-bedrooms each — or about a third of the complex.
Lambert and Boyles worked with A Plus Plumbing Heating and Cooling owner Jason Richards to work out the details for sizing, designing and installing the system. The installation took about a week-and-a-half, including the removal of the old tanks. The five Navien units used two sets of 4-in. PVC vent pipes that run through the roof in an existing 12-in. B vent.
“Efficient hot-water supply was the goal achieved,” Richards says. “The five units are cascaded so when the master unit comes on, it triggers the next one in line to help as needed, and so on until all units are running if necessary. Each time a Navien unit comes on, all five units have equal run times.”
Boyles notes that unlike the old tank system, the external circulating pump and mixing valve could be eliminated since the temperature was set at 120° F. Another key factor in the selection of the new Navien model is the internal recirculating pump and buffer tank that assure an uninterrupted flow of hot water, Boyles notes.
“We have noticed a decrease in our energy cost from NIPSCO, our local gas supplier — a real dollar savings every month,” West says. “We have applied for an energy rebate and I also have seen a decrease in our domestic water use.”
Richards says ease of installation also played a key role in product selection. “One of the main reasons we went with Navien is the ability to use PVC,” he says. “The common venting also makes it less expensive. In this retrofit situation, we could use existing penetrations to run our vents. That saved a lot of labor.”
This article was originally titled “Problem solved” in the November 2017 print edition of PM Engineer.