Once you have established and confirmed with a heating professional that your boiler needs replacing, it is time to look at what you need to know about boilers. When buying a new boiler system unit, it is essential to understand how boilers work and the different types available on the market. A residential boiler primarily uses steam or hot water for space heating. The boiler system works by heating the water in a tank, which supplies steam or hot water through radiators and pipes to produce warmth in the home. Boiler heating systems use single-phase electric current, propane, natural gas, and oil. There are six different types of boilers and three modern ones for residential use in the US. The six types are natural gas boilers, electric boilers, steam boilers, condensing boilers, and hot water boilers. The two main models of boilers for residential use are Hot water boilers and steam boiler systems. The hot water boiling system is a heating and plumbing that heats and pumps water through baseboards and throughout the house. The steam boiler system heats water to create steam that heats radiators throughout the home. Modern boilers are now available with higher efficiency and are environmentally friendly. These are Combi boilers, Heat-only regular boilers, and System boilers. Looking at the AFUE (Annual Fuel Rating) is crucial when purchasing a new boiler. A high-efficiency system has an AFUE of 85 percent or higher. 

A boiler has either high or standard efficiency. Highly efficient boiler systems have an energy efficiency greater than 90 percent and qualify for an Energy Star. An Energy Star is a federal government certification that states that a boiler has more than 85 percent energy efficiency. Combi boilers are the most popular residential boilers because they provide central heating and instant hot water. Due to improvements in their components and condensing technology, they also have an efficiency of 90 percent.