Hot-water heat

Hot-water heat moves warmth with water instead of air. A boiler heats water to provide hot water or steam for heating, which is then sent through a series of pipes. Most gravity systems, which move water without a pump, heat the water to no more than about 180 degrees Fahrenheit, and the cooled water going back to the boiler rarely falls below 120 degrees Fahrenheit. Since the 1930s, many bungalow hot water systems have been converted by adding a pump to the boiler. A pump of this kind is often called a circulator.

Chicago treats these systems as full heating systems. The Heat Ordinance can be met with steam or hot water radiators and other hydronic, or water-based, heating systems. You can tell a hot water radiator from a steam one: hot water radiators have connectors joining their sections at both top and bottom, while steam radiators join them across the bottom only.

Source: U.S. Department of Energy · Historic Chicago Bungalow Association · City of Chicago

Air can collect at the top of a hot water radiator. Bleeding means letting that trapped air out. Hot water radiators should be bled at least once each year, usually at the start of the heating season. Steam radiators, by contrast, do not need bleeding, because their automatic air vents let air out on their own.

A few other checks are yours to make. If one of your radiators is not heating evenly, check whether the floor beneath it has settled; shims under the radiator will bring it back into line. Heated air must flow freely around each radiator, so a decorative cover should have plenty of openings. Poorly kept radiators can damage wood floors. Cast iron radiators take up space, and replacement parts and repair help may be hard to find.

Source: Historic Chicago Bungalow Association

A hot-water boiler holds water under pressure, and a relief valve guards against too much of it. Boilers and pressure vessels are built in a similar way; essentially, a boiler is a pressure vessel. Boilers and pressure vessels can and sometimes do explode. Illinois' mechanical code requires safety and safety relief valves to be listed and labeled, with a rated capacity at least large enough for the equipment they serve. It also requires them to be set no higher than the pressure rating on the boiler's nameplate.

Under Illinois rules, taking apart, reassembling or adjusting a relief valve in a way that affects how it works counts as a repair. A relief valve is a safety part, so leave any work on it to a technician. If you see water around your boiler or its relief valve, tell us what you see.

Source: City of Chicago · Illinois State Fire Marshal · UpCodes (code text)

Your thermostat tells the boiler when your rooms need heat. Programmable thermostats are used to control heating and cooling equipment, and they can adjust temperatures on a set schedule. If you have more than one heating zone, use a programmable thermostat for each zone. Install a thermostat on an interior wall, away from registers, appliances, lighting, doorways, fireplaces, skylights, windows, direct sunlight and drafts. If yours runs on batteries, change them each year.

Source: U.S. Department of Energy · U.S. EPA

A boiler's efficiency is rated the same way as a furnace's. The efficiency of furnaces and boilers is measured by annual fuel utilization efficiency, or AFUE. In general, AFUE is the percentage of the heat in the fuel that becomes space heat instead of being lost. An ENERGY STAR boiler is 5% more efficient than a new standard model. ENERGY STAR lists a boiler more than 15 years old as one sign it may be time to consider replacing it.

Yearly care keeps a boiler safe. The CPSC says a qualified heating contractor should inspect the home heating system every year, checking the boiler, its electrical and mechanical parts, the thermostat controls and the automatic safety switches. The CDC says to have your heating system serviced by a qualified technician every year. Illinois law calls for low pressure hot water heating boilers to be inspected every two years, but boilers in private homes or buildings with fewer than 6 dwelling units are exempt. The steam heat page explains the inspection rules in Chicago.

Source: U.S. Department of Energy · ENERGY STAR · U.S. Consumer Product Safety Commission · CDC · Illinois General Assembly · Illinois State Fire Marshal