Minnesota Housing Project Gets Energy/Comfort Upgrade
Sadly, it’s rare to hear about comfort and affordable housing together as one. Too often, there’s a compromise that must occur. It’s usually comfort that gives way to price and ease of installation.
Yet, managers of Prairie Meadows, a Section 8 housing community in Eden Prairie, Minnesota, stood firm to make the change. Built in the 1970s, the housing complex is undergoing a sweeping retrofit, aided by government funding.
According to Richard Reynolds, boiler maintenance manager at Prairie Meadows, it’s not common for residents of Section 8 housing to experience the comfort of hydronic heat. But, the way facility managers saw it, Prairie Meadows is home for 500-plus residents, the place they go to seek comfort. Why shouldn’t they experience a level of comfort too often reserved for people of greater means?
At Prairie Meadows, the occupants are families with children, seniors, and people with physical disabilities. Apartments range from 850-1,000 square feet with one, two, and three bedroom options. The phased, $10 million renovation to Prairie Meadows, a 10-building, 180-unit campus, concluded in late 2017. While there was some attention given to cracked sidewalks, kitchen upgrades, and plumbing fixtures, the main focus was an energy retrofit to all of the apartment buildings.
Work included door and window replacements, some new appliances, insulation, and some roofing. Though the big, old cast iron boilers still worked, they were gluttons for maintenance and natural gas. According to Reynolds, it was decided that the old systems, though still in operating condition, operated at efficiencies of 65-75 percent AFUE. It’s no mystery that a bump of 20-30 percent fuel efficiency caught the attention of managers tasked with planning the renovations.
Rigors of Winter
Another facet to the need for new boilers was their tendency to require expensive or time-consuming maintenance, which seemed to always occur during the winter months. For those who’ve never experienced winter at its worst in Minnesota, it’s hard to describe the level of discomfort that can happen when a heating system won’t work.
Roaring winds frequently sweep through the state, delivering an average of 170 inches of snow. Temperatures can reach minus 50°F, too cold even for ice fishing. And, try as it might, the state’s travel bureau can’t beat the stats: Minnesota is frequently rated by national weather services as the worst state in 50, winter-wise.
Importance of efficiency
“Our state government has regulations and energy standards when it comes to building efficiency; they’re slowly trying to switch everything to highly efficient systems,” explained Reid Mathiason, project manager at Shakopee, Minnesota-based Associated Mechanical, the plumbing and mechanical contracting firm chosen to install new heating systems at the apartment complex.
“The mechanical systems at Prairie Meadows — with gradually falling energy efficiency measurements — no longer made the cut,” he added. “Even though many were still operating, they had to go.”
The state of Minnesota provides a high level of public and private support for energy-efficient technologies. They offer utility incentives and energy efficiency programs that are accessible to a wide variety of commercial and industrial companies, including financial incentives for upgrades and system-wide improvements.
With efficiency being the number one concern, Laars Mascot FT firetube boilers were selected for the retrofit project at Prairie Meadows. With an efficiency of 95 percent AFUE, input of 199 MBH 10:1 turndown, and the capability of cascading up to 20 boilers for larger structures, and redundancy — the new boilers have given managers and residents new peace of mind during preparations for the inevitability of winter woes.
Associated Mechanical began their work in July 2017, with work that kept them busy through September.
In preparation for the work to begin, demo contractors gutted the mechanical room in each building, including final eviction of the old cast iron boilers.
Associated had a three-man crew installing the boilers. While two technicians finished up one mechanical room, the third began preparations at the next.
One facet of the demolition caught the eye of a technician or two — gradual deterioration of pipes, exhaust flues, and heat exchangers caused by acidic condensate. It’s a tough challenge for on/off boilers combined with record-setting winter temperatures.
But what was once a challenge is now an advantage. The new, modulating-condensing systems welcome the presence of condensate. The boilers and the PVC flues are built to take the presence of acidic condensate in stride. In fact, the boilers gain in operational efficiency by stripping Btus from the fluid before the exhaust process is completed.
The new boilers are wall-hung, which also saved space in the tight basement mechanical rooms, and iping was designed in a primary secondary fashion, according to Nick Kruse, inside sales at St. Paul-based Michel Sales Agency.
“Each apartment building now has two to three of the Mascot boilers,” added Larry Sundberg, technical training and field support at Michel Sales. “The system was designed with a lead-lag configuration with equal runtime for greater efficiency and reliability.”
Boiler operation is now controlled by outdoor reset, which is built into each boiler’s circuitry.
“This alone brought a whole new level of comfort for residents of the apartment complex,” added Sundberg. “Before, residents had one- or two-zone systems that simply operated by an ‘on’ or ‘off’ function.
“Essentially, it was either hot or cold,” continued Sundberg. “Now, with gradual, seamless boiler modulation, and with operation tied to outdoor conditions, residents are finding out firsthand what hydronic comfort truly means — with warmth that’s easily controlled.”
“Laars Mascots were chosen for this job because it had standard features that weren’t even options with other brands, like integral circulating pumps,” said Mike Jackson, Associated Mechanical job site superintendent. “With circulating pumps built into the boilers, we didn’t have to supply one for each system at an additional cost to us, or added work. So those advantages helped as system selections were made, as well.”