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Training is Next for District Heat Customers


by Bob Nuner

In a quick sit-down with Montpelier’s assistant city manager, Jessie Baker, The Bridge got an update recently on the district heat system scheduled to come on line this fall. Most important, Baker noted, are the comprehensive training sessions for building-owners, scheduled for the week of October 10. The sessions will inform owners about the nuts and bolts of the system, how district heat can be expected to work in their buildings, how the system might affect building management, how billing will be accomplished, and so forth.

Customers can expect a two-part bill. One part, called the capacity charge, will reflect their access to the system and help pay system costs, including bond repayments. The other part, the energy charge, will reflect actual energy used by the building. That charge will be determined by multiplying the volume of hot water entering a building by the temperature drop it undergoes in the building’s heat exchanger. These metrics will be posted to a computer in City Hall every 15 minutes, giving a picture of heat utilization both city-wide and in individual buildings.

The buildings’ heat exchangers will extract heat from the incoming water, so that while that water is around the boiling point, the temperature of the water returning to the system will be about 170 degrees Fahrenheit. The measured energy usage will be billed for at the straight, passed-through rate the state charges Montpelier for the heat that leaves the state’s heating plant, on the Winooski behind the state office buildings, via the plant’s “city room” heat exchanger. There, the plant’s steam heats the district heat system’s circulating water. (State buildings are steam-heated, so that the plant’s steam is not converted to hot water before heading out to those destinations.)

Liquid, but under pressure, the district heat system’s outgoing water will be hot enough that, if vented, the release would turn to steam. Baker noted that the pipes delivering the hot water are so well insulated that, in the mile of piping it takes to get to Union Elementary School, the water only loses about one Fahrenheit degree of heat.

In addition to building-owners, city crews will receive training in handling the system. Baker noted that the crews are already “stellar at managing our water system, which is under extreme pressure and is actually incredibly dangerous. We have very high water pressure in Montpelier, but it’s not hot. So [the district heat water] is a new thing for our Public Works people to manage.”

Ever-Green Energy, the St. Paul, Minnesota, district heat consulting firm subcontracted by the district heat project’s engineering firm, Hallam-ICS, will conduct the training for both the building-owners and the Public Works staff.