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By Thomas Renner
Some things get better with age. Wine, friendships, blue jeans, and even cheese stand up over time and improve as the days, months and years drift along. “The best tunes,’’ poet Ralph Waldo Emerson said, “are played on the oldest fiddles.”
Boilers, however, do not age as well as Emerson’s fiddles. Boilers have a life span of 15-20 years if they are properly installed and serviced. That’s not a very long period, and as boilers age, they become far less efficient and much more costly to operate.
Keith Trafton and his team at Excel Mechanical discovered just that in overhauling the heating elements at a large apartment complex in Portland, Maine.
The 166-unit complex was built in 1973, and the three-story buildings have a range of apartments, from 1-4 bedrooms. The boilers that provide heat and hot water for the units, however, had been in place for more than two decades and were operating at just 80 percent efficiency.
“They were leaking, and repair bills were becoming excessive,’’ Trafton said. “It didn’t make sense to keep repairing them any longer. The industry standard for boilers is 12-15 years, and these units were well past that.”
Working with Tom Protasewich of Emerson Swan, the Excel team replaced six units in three buildings with HTP Elite XL commercial boilers. The HTP units have a 97 percent thermal efficiency rating but also feature one of the smallest footprints of any commercial boiler.
“It’s a big improvement over what had been in there previously,’’ Trafton stated. “Improved efficiency was the primary goal, and the building owner is going to see some big energy savings in their budget.”
Age Issues
Inefficiency is the most consequential issue with aging boilers, but there are also other concerns that create additional stress for building owners.
Decreased efficiency in aging boilers is the costliest challenge. As a boiler ages, it requires more energy to produce the same amount of heat and leads to higher energy expenses. The difference is significant for homeowners but is especially dramatic in large commercial properties where boilers serve multiple dwellings and residents.
Aging boilers also suffer frequent breakdowns and need for repairs. The issues could arise from improper installation or delayed service, but low water pressure, malfunctioning thermostats and debris and limescale buildup can also contribute to boiler breakdowns. Exposure to water can cause corrosion within the boiler, leading to leaks and issues with components. Blocked vents and flues, pump failure and air trapped in the system can impact boiler performance.
There are also safety risks, as cracks in a heat exchanger or pressure vessel can create dangerous situations, and carbon monoxide leaks due to potential issues with combustion or venting can cause concern. In January, a boiler malfunction caused a carbon monoxide leak at a New York state elementary school. A carbon monoxide alarm alerted school officials to the issue, which resulted in a multi-day closure.
The challenge for Trafton and his crew was managing the switchover while still maintaining thermal comfort for the apartment residents as the cold Maine winter took root. “The project started in November and December,’’ Trafton said. “We had to take out the old stuff, but we couldn’t leave the entire building without service. We looked at the drawings and made sure the new units were going to run. We pulled them out one at a time, and once we got them in, we had to drop in PVC for venting.”
Numerous advantages
The building owner and residents saw an immediate impact from the installation of the HTP Elite XL boilers.
The unit modulates the output of the burner during operation to match system demand. Modulation is an important feature of the unit, as it minimizes wasted energy, reduces heating bills and improves comfort by reducing temperature fluctuations.
“The boilers that had been installed were greatly oversized,’’ Protasewich said. “It was really inefficient, and they were either 100 percent on or 100 percent off. There was no in between. With these units, they won’t need to go over 50 percent of heating capacity. It’s going to save the owners a lot of money because of the dramatic improvement in efficiency.”
The set point can be changed by an internal or external signal to enhance system performance. The Elite XL also features an outdoor sensor that adjusts the unit set point based on the outdoor temperature measured by the sensor to provide great efficiency.
The system is further improved by redundancy in the setting up of multiple boilers. If one boiler fails or needs maintenance, the second boiler will continue to operate. That feature prevents a complete shutdown, ensuring consistent hot water and heating supply. It also allows for faster recovery and distributes the workload more evenly.
The ELX-650FBN models deliver up to 650K BTUs per hour and feature a high-resolution touch screen that provides a clear visual of the system operation to monitor and troubleshoot.
The Right Choice
In Maine and some other states, especially in New England, boiler replacements are becoming rare. Many building owners are switching to heat pumps, driven in large part by incentives from government and business entities. Even some boilers that are still operating efficiently are being replaced by heat pumps.
“The challenge of changing a building like this to heat pumps is the huge upfront costs,’’ Protasewich explained. “It’s cost prohibitive to a point. In this case, a direct replacement was a great option.”
“This was a neat project for us,’’ Trafton said. “We work on tons of boilers with clean energy and heat pumps, but we’re not seeing as many of these large boiler swap outs. We were able to get a lot of our team members trained. The building owner is going to save a lot of money with improved efficiency, but we also saved a lot of money because we didn’t have to do a lot of re-engineering. They sit on the floor similar to the old boiler, so it didn’t require a lot of re-working and we were able to start up quickly.”
Thomas Renner writes on building, construction and other trade industry topics for publications throughout the United States.
