Replacing an ancient cast-iron boiler with a modern, high-efficiency equivalent may offer significant standalone benefits in terms of operational and energy costs, reliability, and fast heat generation … but it’s still only half the story.
A good heating system has to be regarded holistically — all parts have to work efficiently together. At The Macomb Group, putting best-practice into action means delivering the best possible combination of components for the most outstanding result.
A perfect example has been the recent replacement of a heating system at Grand Valley State University, in what is the first phase of an ongoing program across much of the campus.
Like most universities in the United States, Grand Valley is a mix of old and new buildings. This includes a group of dormitories that are up to 30 years old and rely on ancient cast iron boilers.
It was not just that they were old, says Mike Boyd, West Region Sales Manager of The Macomb Group. The entire system was also inflexible and noisy — a big distraction for the young residents.
“It used constant-speed pumps,” he explains. “That’s one speed, all the time. Whether you’re using the whole building, just one side of the building, or even just one room, they deliver the same flow.”
Imagine a situation in which half the building is closed, with all the valves turned off, but the system is still pumping water around at the same speed.
“You’re still using the same amount of horsepower whether it’s at full flow or half flow. It’s working harder, even though it doesn’t need to. Inside that little pump, the impeller gets shoved to one side of the casing, which causes wear on the bearings,” Mike says. “In extreme cases, it can snap off the shaft in the pump or, as the pressure rises, the closure mechanism on the weakest valve will vibrate and hum, making a lot of noise.”
Meanwhile, all the surplus energy that’s being generated is going up the vent stack.
These challenges called for a two-part solution from The Macomb Group: replacing the cast iron boilers with an array of three Lochinvar Knight commercial boilers (two at 300,000 BTU and one at 400,000) and pairing them with variable-speed Wilo pumps.
The Lochinvar units offer up to 94.6% thermal efficiency, using a fully modulating burner with 5:1 turndown. The three Grand Valley boilers are essentially networked, with one central “brain” running them.
The Wilo devices use ECM motor technology to cut energy consumption by up to 80% and automatically adjust to system demands.
“We have an outside reset on the building that monitors the external temperature,” Mike says. “As it gets colder, it automatically turns the temperature of the water up.”
Another pump on the system works on differential pressure so as the valves in all the rooms on the system are opened or closed. It automatically ramps up and down based on overall demand, so the pump runs only as fast as it has to.
Mike says, “The pump is not being strained, so it’s going to last longer. And the valves don’t hum — so we don’t have any upset college students!”
But it’s not just the students who are happier. Mike estimates the school will save 50% of the energy it used to consume in this area.
“We’re playing our part in helping keep the cost of education down!” he says.