October is when exposed water becomes an emergency. The first fall freeze usually lands this month, earlier in outlying areas and later along the lakefront and in the city. At O’Hare the average first freeze is October 19, and National Weather Service records show one as early as September 22, in 1995. That makes early October the right time to winterize equipment that holds water outdoors.
A rooftop doesn’t wait for the official reading at O’Hare. On a clear, calm night, roofs and exposed piping lose heat to the open sky and can fall below freezing while the official reading is still in the mid-30s. That is enough to cause trouble for a trap, a coil, or a tower basin that is still in summer mode.
Walk Every Component That Holds Water Outdoors
Work with the design you have. A drain-down, heat trace, or basin heater only helps if the equipment was built to use it.
- Cooling towers and condenser-water piping — follow the tower manufacturer’s winter sequence and confirm basin heat, sump protection, and outdoor piping. A full basin with no heat is how a tower cracks.
- Rooftop condensate — traps, drain lines, and pans on running units need a path that won’t freeze the first night the unit sits idle.
- Coils on the outdoor-air path — hydronic coils, and any coil that sees outdoor air, need a working freezestat and a sequence that closes and protects them. Glycol belongs only in systems designed and maintained for it.
- Heat that protects the building, not just the occupied rooms — vestibules, loading docks, stairwells, and cabinet unit heaters are what warehouses and multi-tenant buildings usually find frozen first.
- The fall maintenance visit — if heating startup didn’t happen in September, it has to happen in October. Combustion checks and freeze protection belong on the same trip whenever the equipment allows.
Three Moves This Month
List Every Water-Bearing Component Exposed to Outdoor Air
Towers, outdoor piping, condensate lines, and coils on the outdoor-air path.
Confirm the Winter Sequence on Each One
Heat, drain-down, or circulation, depending on how that equipment was designed.
Get the Fall Visit on the Calendar
If it isn’t scheduled yet, book it now. If a freeze hits first, call 847.498.4590 for 24/7 emergency service.
The work this month is specific: protect the water, prove the heat, and finish the inspection while the weather is still a warning.