Understanding the Heating System at Nottingham School
Mike Davey, who made a presentation to the School Board last month, agreed to answer some of my questions about the heating system.
Davey thought it was important for people to understand that Nottingham School has an unusual heating system. Most readers are likely familiar with a typical home heating system, which has a boiler and pumps that send hot water from the boiler to radiators elsewhere in the house. However, that’s not how the heat works at the school.
Forced air is used to heat the school. There are no radiators. Hot water from the boilers is pumped to air handling units. In these units, there’s a “reheat coil” through which the hot water flows. A fan draws air through the reheat coil to transfer the heat from the coil to the air and then into the classroom.
The propylene glycol in the system is an antifreeze. Most heating systems are designed not to need antifreeze by keeping all the pipes inside the heated, insulated envelope of the building. The school’s heating system isn’t like that. In the attic, pipes run through a short, unheated, uninsulated area to reach the air handlers. Without the propylene glycol, these sections of pipe could freeze and burst.
I told Davey about the children who have reported symptoms that they claim are caused by propylene glycol fumes. I wondered if there has been some chemical reaction within the system caused by the acidic conditions that have dissolved something that was expected to be inert or perhaps the children are misattributing the cause of their symptoms. Davey is unaware of children reporting symptoms from other propylene glycol leaks he’s been involved in or heard about. The manufacturers say that propylene glycol and the additives used to treat it are non-toxic.
Many buildings have redundant heating systems. It’s common for homes to have redundant systems, perhaps a boiler and a wood stove, a propane heater, or a heat pump. The school had no redundancy until this week. Per ENE Systems' recommendation, some 5 KW 480 Volt ceiling-mount electric heating units were installed by ENE Systems this week as backups.
Another unusual aspect of Nottingham School is that despite being a two-story wood-truss building, it does not have a sprinkler system in case of fire.
There has been some confusion about the roles of EEI and ENE. ENE provides heating maintenance services, and EEI, a subsidiary of ENE, provides consulting on the design of heating systems. They are not the school’s regular HVAC vendor. They were not involved in the school’s 2023 boiler replacement. The school has contracted with these companies for emergency services because of the ongoing series of failures in the school’s heating system.
The heating woes at Nottingham School have attracted outside coverage. WMUR aired a short piece about the school. NH School Scoop has mentioned it twice.
