The Healey building is a sealed building (sometimes referred to as negative pressure) the windows do not open. Building code requires that outside air be circulated into the building and the stale air removed. The ERU allows the control of the air coming into the condominium area.
If this did not happen air would get into the building from open doors, elevators shafts etc.
ERU intake fans are installed on floors 3, 5, 7, 9, 11, 13, 15.
Exhaust units are on even floors 4, 6, 8, 10, 12, 14, 16
How all this works:
•There are HVAC units in the ceiling of the common areas near the elevators on each floor. These units heat each floors common elevator area in the winter and cool in the summer.
•The ERU units on the odd numbered floors brings in outside air.
•This air flows through the odd number floors and the one above and is conditioned (heated and cooled) by hallway air heated and cooled by the HVACs in the ceiling at the common areas before being exhausted out of the building at the even number floors exhaust unit.
•The hallway air is circulated under each condominium entry door – that is why there each unit’s door is about 2 inches above the threshold – the air is exhausted from each condominium unit via the exhaust grates in the bath room(s) to the even number floor exhaust unit.
•When there is extremely cold outside air as was experienced in mid January 2014 and nighttime lows were in the single digits the system cannot heat the air fast enough, hence the cold air in the hallways. Same would be true for extreme hot days in the summer. The hallways would seem very warm.
•The HVAC units in the ceiling in the common area on each floor were never designed to provide total comfort for extreme temperatures (hot or cold outside temperatures).
•The common area window energy repair-or-replacement project will help keep the temperature more stable in the common areas when completed.