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Heating and cooling systems
Most homes have a few machines that keep them warm, cool and fresh. Each page here explains one of them: what it does, the parts that matter, what tends to go wrong, and what you can safely check yourself.
In this section
- Gas furnaces
How a gas furnace heats, what AFUE means and the signs worth a closer look
- Older furnaces
Gravity and coal-era furnaces, gas conversions and how to judge a furnace's age
- Steam heat
How steam boilers and radiators work, air vents, banging and boiler rules
- Hot-water heat
How hot-water boilers and radiators work, bleeding, pressure and efficiency
- Central air conditioning
The parts of a split system, what is normal and the signs of trouble
- Heat pumps
How a heat pump heats and cools, and how it copes with Chicago cold
- Ductless mini-splits
Ductless cooling and heating for homes and rooms without ducts
- Window and wall air conditioners
Window, through-the-wall and PTAC units: sizing, power and care
- Thermostats and zoning
Programmable and smart thermostats, placement, zoning and batteries
- Home ventilation
Fresh air, bathroom and kitchen fans, range hoods, and ERVs and HRVs
- Indoor humidity
The right humidity range, humidifiers in winter, dehumidifiers in summer
- Air filters and air cleaners
Furnace filters, MERV ratings, changing filters and what air cleaners can do
- Gas water heaters
Gas water heater types, burning air, venting and the signs of backdrafting
Other sections
- How it works
The few ideas behind every system: heat, air, fuel, ratings and size.
- Care through the year
What to check before winter, before summer and in between.
- Chicago homes
The climate, the city's rules, older homes, permits and help with bills.
- Safety
Gas, carbon monoxide, venting, warning signs, asbestos, lead and mold.
- Choosing and paying for work
Repair or replace, hiring well, what affects cost and how to pay.