MacDonald Campus, a 1,600-acre part of McGill University, is home to over 12,000 staff and students. It houses the Faculty of Agricultural and Environmental Sciences, School of Human Nutrition, Institute of Parasitology, and the McGill School of Environment. The campus manages power, maintains over 70 buildings, and cares for extensive horticultural assets and a 7.5-mile road network.
The Challenge:
Key engineering challenges included a single-vent stack design, boiler feedwater cooling requirements, and maximum pressure drops. Taller stack heights and either bigger flues or a fan were required for effective draft control and increased energy savings. ENERVEX and EnviroAir were engaged to design a custom mechanical draft and heat recovery solution.
The Campus needed an efficient boiler exhaust system replacement for its old Economizer on an existing Fulton boiler. Key engineering considerations complicated the design, including a single-vent stack design, boiler feedwater cooling requirements, and maximum pressure drops. MacDonald Campus also required taller stack heights and either bigger flues or a fan to achieve effective draft control and increased energy savings. They engaged ENERVEX and our rep EnviroAir to design a custom mechanical draft and heat recovery solution that could solve these challenges.
The Solution:
After calculations, it was clear that the Fulton VMP-150 boiler could not operate without mechanical draft. ENERVEX installed a VHX Economizer vertically to vent the boiler system. An ENERVEX PowerStack EPS1 Chimney System, with diameters ranging from 12" to 22", was installed to ensure negative pressure even at high fire.
The VHX Economizer met the campus's requirements for flue gases at 425°F and 80% EA, with a maximum allowed pressure drop of -0.05"WC. Boiler feedwater for the water-side heat sink (20 GPM) could be cooled to 115°F, with a targeted final flue gas temperature of at least 220°F.
An HRC80 Economizer Controller with an integrated bypass modulating damper wase added to protect against erratic draft, inconsistent supply make-up air, uncontrolled flow rates, and mechanical or electrical failures. By monitoring inlet and outlet flue temperatures, the HRC80 Economizer Controller can dynamically adjust as stack pressure and water temperature fluctuate.
The Result
These products are designed for lower-cost installation, protection against draft problems, safety, and flawless performance with other ENERVEX products. The VHX Economizer and heat recovery solution saves MacDonald Campus an estimated 577,000 BTUs per hour and $46,000 in annual energy costs.
