High Efficiency Boilers
High efficiency boilers became popular during the energy crisis in the 1970s because they helped lower consumers' energy bills. Boilers have an A to G rating for efficiency. It's always recommended that you choose a boiler that has an A rating. All "A" boilers are condensing boilers.
A high efficiency condensing boiler works by recovering "waste heat" that typically exits a house from the flue of a conventional non-condensing boiler. Its extra-large heat exchanger is corrosion resistant and maximizes the heat transfer from the burner. It also recovers any heat that might otherwise have been lost with flue gases. When it switches to the condensing mode, these flue gases emit their latent heat, which is then recaptured by the heat exchanger in the boiler. The gases coming out of the flue in a condensing boiler have a temperature of 50-60° F as compared to the 120° or more in a non-condensing boiler.
Boiler efficiency has a direct impact on energy bills. The more efficient your boiler, the less fuel you use, which results in lower bills. A boiler's maximum efficiency is reached when it operates at full load. Boilers are rated as per their annual fuel utilization efficiency, or AFUE, to reflect losses in actual installations. AFUE is the parameter used to compare and test two boilers under similar conditions. It is based on a residential load profile that is different from that of a commercial building. The National Appliance Energy Conservation Act of 1992 requires that small gas boilers have an AFUE of at least 80%. The Energy Star Program, run by the U.S. Environmental Protection Agency and Department of Energy, awards an Energy Star label to boilers that have an AFUE of 85 % or more. There are boilers on the market that claim an AFUE of 97%.
It is economical to buy a high efficiency boiler as it will eventually prove itself to be a good investment. The cost of a high-efficiency boiler can be up to twice that of a conventional boiler. However, high efficiency boilers pay for themselves in about five years or less when you consider the rising fuel prices and the life of the boiler, which is guaranteed at 25 years. Payback period is the time taken to recover an investment and we can see it as the ratio of investment to annual savings. For example, a new high-efficiency boiler costs $10,000 to install and saves $2,500 per year in fuel costs. The payback period will be four years.
High Efficiency Boiler Brands
The following companies manufacture high efficiency boilers:
- Buderus Hydronic Systems
- Newmac Mfg.
The good news is that replacing an old boiler with a new high-efficiency condensing boiler could give you immediate savings of about 30% on your heating bills. High efficiency boilers are more than 90% efficient, which means that more than 90% of the gas consumed when the burner is firing is converted into heat for your heating and hot water system.