Apartment Complex’s Energy Efficiency Soars (Part One)

Rinnai Combi Boilers Save Energy and Installation Costs

Apartment Complex’s Energy Efficiency Soars (Part One)

Last year, Meadowbrook Gardens, a 1960s-era garden apartment complex in Parsippany, N.J., experienced an extensive renovation, including upgrades to the heating and hot-water systems in the complex’s 10 buildings, which collectively house 151 units. The apartment complex owner was looking to individualize utilities by unit and increase overall energy efficiency. He ultimately selected Rinnai Condensing Combi Boilers.

Setting the Scene

At the time, each building had an inefficient 1 million-Btu hot-water boiler located in a common basement, which provided space and water heating for all of the units in the building. In addition to being inefficient, the large, floor-mounted boilers were occasionally threatened by standing water as a result of flooding from a nearby creek. To address these problems, the property owner hired Beta American Services, of Oakland, N.J. The contractor recommended replacing the existing hot-water boiler with smaller, more efficient wall-mounted condensing boilers—one for each unit. With the property owner’s approval, the contractor began researching different high-efficiency combination, or “combi” boiler models.

Making a Selection

In the end, Beta American Services selected the Rinnai E75CN high-efficiency condensing gas boiler for the job.

“Before the Rinnai presentation, another brand of boiler was specified for the retrofit, but based on the project’s Btu needs, the Rinnai unit was clearly the best choice,” said Pete Monahan, owner of Beta American Services. “The original spec was for a 200,000-Btu unit, and the heat load limit for the apartments was significantly lower, so the Rinnai boiler was a better fit in regards to sizing and modulation range, and it has a great heat exchanger. If we’d installed the higher-Btu boiler, it would not have modulated very well, essentially staying in fixed low-fire the whole time, instead of being used to its intended capacity.”

The Rinnai E75CN is a 75,000-Btu, highly efficient boiler designed for homes and apartments with smaller domestic hot-water requirements—one to two baths. This made it an excellent fit for Meadowbrook Gardens, which offers both one- and two-bedroom floor plans—750 and 900 square feet, respectively—each with one bathroom.

A combi boiler, the E75CN uses an integrated single-speed boiler pump, expansion tank and three-way valve that provides domestic priority and supplies both heat and continuous hot water. The boiler also comes with a factory-assembled low loss header plumbing kit. And, with its compact wall-mounted design, it takes up considerably less space than traditional boilers.

Reducing Installation Costs

After selecting the ideal boiler model for the individual units, the next order of business was developing a way to reduce installation costs for the budget-conscious property owner.

“They wanted the upfront cost to be as low as possible so we had to figure out a way to get 151 of these boilers properly installed and vented very quickly,” Monahan said. “We developed a plan to build the boiler assemblies off-site in our shop, mount them on painted plywood and transport them to the jobsite, virtually ready for installation.”

Beta American Services drew up a schematic for the boiler assembly and then built one to serve as a template. The team wrote down every dimension, cut and piece needed and created an AutoCAD drawing of the assembly and numbered every component that accompanied the boiler. Then, the team made and stocked storage bins for each individual component and built six work stations for the fabrications.

“After getting over the learning curve, the guys at each work station were eventually able to fabricate four boiler packages a day,” Monahan said. “We’d wait until we got a full load and then take them to the jobsite and mount all the boilers for a building. And, we set it up so there would be only minimal downtime for the tenants. We had to do a lot of planning ahead of time to make it all work, but it ended up going very smoothly.”

Stay tuned for part two to learn about the multifamily complex’s significant savings.

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