Whole-house hot water and steam boilers heat water to produce either steam or hot water for heating throughout a house. Gas-fired whole-house hot water and steam boilers are fueled with natural gas or propane. Oil-fired boilers use oil as a fuel source. Oil burners are used with oil-fired boilers to provide the heat source to heat water or convert it to steam. Whole-house hot water and steam system accessories are used in the installation of whole-house hot water and steam systems or to replace worn parts.