Selecting a boiler for a hydronic heat system requires making decisions about energy efficiency and sizing. A hydronic system heats, literally, from the floor up. Hot water circulated through loops embedded under flooring or in radiators at baseboard level creates comfortable warmth that radiates gently into the room. The key element in a hydronic system is a boiler that heats enough water to supply the system with consistent heat, and does it with as little heat/energy loss as possible. Boilers have long service lives — as long as 25 to 30 years — so it’s important to make decisions based not only on present needs and conditions but on future projections, as well. Here are some considerations for selecting a boiler that meets those standards:
Gas-fired boilers that heat the circulating fluid in hydronic systems are rated according to AFUE (annual fuel utilization efficiency) percentage. The figure expresses the amount of gas consumption converted into usable heat versus the amount lost in the combustion process. The minimum AFUE for standard-efficiency boilers manufactured today is 80 percent.
High-efficiency boilers, known as condensing boilers, utilize secondary heat exchangers to derive more heat from the condensation process. These units have AFUE ratings over 90 percent. However, actual net money savings from a high-efficiency boiler include other factors such as the local climate, the overall efficiency of the home and the cost of natural gas.
Sizing is a critical function performed by your HVAC contractor. Done correctly, it matches the output of the boiler’s Btu rating to the total heat loss of the home. Heat loss is calculated on a room-to-room basis, figuring the average rate of loss through walls, floors and ceilings. If the boiler is too small, the system will under-perform, run longer and use more energy to reach thermostat settings. A system that’s too large will cost more up-front and have a shorter usable life due to excessive on/off cycling.
For more than 77 years, Geisel Air Conditioning, Heating & Plumbing has served homeowners in the greater Cleveland area. Contact us today for more information on selecting a boiler for your hydronic system.
Our goal is to help educate our customers in Western Cleveland, Ohio about energy and home comfort issues (specific to HVAC systems). For more information about selecting a boiler and other HVAC topics, download our free Home Comfort Resource guide.
For those Do it Yourselfers who would rather take control of your own indoor comfort, you can shop our online store for replacement parts, products and accessories!
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