Boiler Buying Guide: How to Choose the Right Boiler for Your Chicago Home

Step 1: Match the Boiler Type to Your Existing System

The single most important constraint when buying a new boiler is your existing distribution system. You cannot simply swap a steam boiler for a hot water boiler — the piping, radiators, and controls are fundamentally different.

If you have a steam system (single-pipe radiators, no circulator pump, a gauge glass on the boiler): you need a steam boiler replacement. Converting to hot water is possible but requires replacing all the piping and radiators — a major renovation.
If you have a hot water system (baseboard heaters, two-pipe radiators, a circulator pump): you can replace with any hot water boiler, including high-efficiency condensing models.

Step 2: Choose the Efficiency Level

Boiler efficiency is measured in AFUE (Annual Fuel Utilization Efficiency) — the percentage of fuel energy converted to heat.

80–85% AFUE (non-condensing cast iron): The traditional choice for steam systems and some hot water systems. Lower upfront cost, higher operating cost. Required for steam systems — condensing boilers cannot be used with steam distribution.
90–95% AFUE (mid-efficiency condensing): Good balance of upfront cost and efficiency. Requires a condensate drain and PVC venting.
95–98% AFUE (high-efficiency condensing): Highest efficiency, lowest operating cost. Best for hot water systems with good insulation. Requires PVC venting and a condensate neutralizer.

In Chicago, where heating season runs roughly October through April, the payback on a high-efficiency boiler is typically 5–10 years depending on gas prices and usage.

Step 3: Size the Boiler Correctly

Boiler sizing is measured in BTU output. An oversized boiler short-cycles — it fires, heats the water quickly, shuts off, and repeats — which reduces efficiency and causes wear. An undersized boiler runs constantly and cannot maintain temperature on the coldest days.

Proper sizing requires a heat loss calculation based on the building's square footage, insulation levels, window area, ceiling height, and local design temperature. For Chicago, the design temperature is typically -4°F to 0°F.

D's Air & Heating performs a heat loss calculation for every boiler replacement. We do not size by rule of thumb.

Step 4: Venting Requirements

The venting method depends on the boiler type:

Non-condensing boilers: Vent through a masonry chimney or B-vent (double-wall metal flue). If the existing chimney is in good condition, it can often be reused.
Condensing boilers: Vent through PVC pipe (typically 2–3 inches in diameter) that can run horizontally through a wall. No chimney required. This is a major advantage in buildings where the chimney is deteriorated or shared.

Step 5: Zoning Capability

Hot water boilers can be zoned — different areas of the building can be controlled independently using zone valves or multiple circulator pumps. This is not possible with steam systems, which heat all radiators simultaneously.

If you are replacing a hot water boiler and want to add zoning (for example, separate thermostats for each floor of a two-flat), this is the time to do it. The additional cost is modest compared to the total replacement cost.

Step 6: Brand and Warranty

Major boiler brands available in Chicago include Weil-McLain, Peerless, Crown, Dunkirk, Navien, and others. Key warranty considerations:

Heat exchanger warranties range from 5 years to lifetime depending on the brand and model.
Parts warranties are typically 1–5 years.
Most manufacturers require installation by a licensed contractor and registration within 30–90 days for the full warranty.

D's Air & Heating installs and services multiple boiler brands. We handle warranty registration as part of every installation.

What Does a New Boiler Cost in Chicago?

Installed costs for a residential boiler replacement in Chicago typically range from $4,000 to $12,000 depending on the boiler type, efficiency, size, and complexity of the installation. Steam boiler replacements tend to cost more than hot water replacements due to the complexity of the system. Commercial boiler replacements are priced separately based on capacity and scope.

Contact D's Air & Heating for a free estimate on a boiler replacement for your Chicago home or building.