HVAC Services in Chicago, IL

Heating and Cooling in Chicago

Chicago has one of the most demanding heating climates of any major American city, with design temperatures near -5°F and stretches well below that. It also has genuinely hot, humid summers. Equipment here has to do both jobs well, and much of the housing stock was built for only one of them.

Know Which System You Have

Forced Air

Bungalows and post-war housing typically have a gas furnace and ducts. Straightforward to service, straightforward to add central air to.

Steam

Common in pre-war two-flats, courtyard buildings and greystones. A boiler makes steam that rises to cast iron radiators. Efficient enough when properly balanced, and notoriously badly balanced in practice.

Hot Water (Hydronic)

A boiler circulates hot water through radiators or baseboard. More controllable than steam, zonable, and quieter.

The Chimney Liner Problem

This is the single most misunderstood item in a Chicago furnace replacement, and it catches homeowners every winter.

An older 80% AFUE furnace vents hot flue gas up the masonry chimney. The water heater is usually connected to that same chimney and relies on the furnace's heat to carry its own exhaust up and out.

Install a 95% condensing furnace and the physics change entirely. It vents through PVC out a side wall. The water heater is now alone in a chimney flue sized for two appliances. Its exhaust moves slowly, cools, and condenses. That condensate is acidic and it destroys mortar joints from the inside, which over a few winters can lead to flue blockage and carbon monoxide entering the house.

The correct response is a stainless steel liner sized for the water heater alone, $1,200-$2,500. A quote for a high-efficiency furnace on a chimney-vented water heater that does not include a liner is incomplete. Ask about it directly.

Sizing for Chicago

Chicago's design temperature makes correct sizing more consequential than in mild climates, in both directions.

• Undersized and the house cannot hold temperature during a January cold snap, which is when it matters most.
• Oversized and the furnace short-cycles, which wears the heat exchanger, produces uneven temperatures, and on the cooling side leaves the house clammy in July because the unit never runs long enough to dehumidify.

Insist on a Manual J load calculation. In an older Chicago home the answer usually depends heavily on what has been done to the attic and windows, which is exactly why a square-footage rule of thumb fails here.

Getting Steam Heat to Work Properly

Most complaints about steam heat are balance problems, not capacity problems.

• A cold radiator on one-pipe steam usually needs a new air vent. They cost a few dollars and clog with scale.
• Banging pipes mean condensate trapped in the line. Check that each radiator pitches back toward its supply valve, and shim it if not.
• The far end of the building is cold while near radiators roast — this is a venting balance issue, corrected with differently sized vents on the mains and radiators, not by turning the boiler up.
• Two-pipe systems with failed traps leak steam into the return, wasting fuel and starving other radiators. Traps are consumable and should be checked periodically.

A contractor who understands steam is worth finding. Many do not, and the default advice from a technician who does not is to replace the boiler.

Air Conditioning Retrofits

Homes with ducts can usually take conventional central air for $5,000-$9,000. Homes with radiators and no ducts have two options:

• Ductless mini-splits — one outdoor unit, wall-mounted heads in the rooms that matter. $4,000-$7,000 for a single zone, $12,000-$20,000 for a multi-zone system. Also provides supplemental heat in the shoulder seasons.
• High-velocity small-duct systems — flexible two-inch ducts snaked through existing cavities. More expensive, less visually intrusive than wall heads.

Costs in Chicago

Autumn Maintenance That Matters

• Book the tune-up in September. In October and November the same technicians are running emergency no-heat calls and you will wait.
• Have the heat exchanger inspected on any furnace over 15 years old. A cracked exchanger is a carbon monoxide risk and it is not visible without inspection.
• Test carbon monoxide alarms on every level. Illinois law requires them within 15 feet of every sleeping area.
• Clear the exterior vent terminations on a high-efficiency furnace. Snow drifting over a PVC intake will shut the system down, always at night, always in a storm.

Tips for Chicago Homeowners

1. Ask about the chimney liner before signing for a high-efficiency furnace.
2. Get a Manual J. In a Chicago house the rule of thumb is reliably wrong.
3. Try the vent first on a cold one-pipe radiator before calling anyone.
4. Schedule service in September, not November.
5. Keep the high-efficiency vent terminations clear of snow all winter.