Gas Hot Water Boiler

A: A gas boiler heats a home or building by combusting, or burning, gas and transferring that heat of combustion into water through a heat exchanger (often called a boiler or pressure vessel) and circulating it through cast iron radiators, baseboard, air handlers, or other radiators in the conditioned or heated space. Natural gas and propane are very clean-burning, abundant, cost-effective energy sources that generate heat.

A: A gas boiler provides the best comfort in old or new homes, with affordable operation, fast recovery from thermostat night setbacks, and nearly endless hot water with properly integrated tank storage systems.

A: A gas boiler provides quiet, even comfort without drafts produced by forced air systems that often have central ductwork, like furnaces and heat pumps. Department of Energy studies site duct distribution energy losses between 25% and 40%. Boilers, recognized to have only 5% distribution energy losses, are said to have the best efficiency and superior comfort in cold climates.

A: Gas boilers use natural gas or propane.

A: All manufacturers indicate that gas boilers must be serviced by a qualified professional at least once a year. Some "space-saving" condensing gas boilers require two or more heating professional service visits per year to prevent the voiding of the warranty.

A: To help keep your boiler running smoothly, have it tuned up annually by qualified heating professionals and regularly inspect the boiler and surrounding area as indicated by the boiler manufacturer.

A: Maintain your gas boiler by having a heating professional inspect and test all safety controls, verify proper and safe combustion, and replace worn and failed parts. Annual tune-ups are typically recommended, although some condensing boilers require two heating professional tune-ups per year to maintain warranty coverage. Conventional non-condensing gas boilers have historically required much less maintenance than condensing boilers with complex controls and tight water and flue passes. An industry reference cites four times as many condensing boiler parts are sold as conventional boiler parts, even though the referenced sales of conventional boilers are seven times higher than condensing boilers.

A: Important optional safety features to consider when choosing a gas boiler include a low water cutoff (required in some jurisdictions), combustible gas and carbon monoxide sensor, and controls with onboard diagnostics to assist in service and record anomalies for professional review. A "high water" cutoff on condensate pumps for condensing boilers is also recommended. Other features, such as a pressure relief valve and a temperature and pressure gauge, must be installed per ASME code.

A: Gas boilers have a heating capacity, usually quantified in BTU/hour or MBH (thousand BTU per hour), which indicates how much heat the boiler can produce. The higher the output MBH rating, the greater the heating capacity. Output is always lower than the input due to losses out of the vent system or chimney. This is further reduced by piping and pickup losses. Pickup typically refers to how much energy is required to heat the boiler and piping; higher-mass cast iron boilers have excessive weight and high water content, making them slower to heat and less energy efficient than low-mass boilers in general. The energy needed to raise the temperature of 5 quarts of water by 70°F is about the same as that required to heat 100 pounds of cast iron by 70°F. This means that low mass and low water content are very important for efficiency and responsiveness from a cold start.