Do I Need One of the New High Efficiency Boilers?
How efficient are high efficiency boilers?
New high efficiency boilers are significantly more efficient than their predecessors. Energy-efficiency of boilers and furnaces is measured by annual fuel utilization efficiency (AFUE), which is a ratio of annual heat output to fossil fuel consumed by the boiler or furnace in a year. This means a boiler with an AFUE of 70% converts 70% of the energy produced by combustion of the fuel to heat to the home; the other 30% is lost. High-efficiency boilers have an AFUE of 90% – 98.5 %, compared to an AFUE of 56% – 70% for older models. You can easily compare the efficiency of new boiler and furnace models, thanks to the Federal Trade Commission requirement that all new ones display their AFUE.
What is a condensing boiler; is it the same as a high-efficiency boiler?
A condensing boiler is high-efficiency because it captures and reuses some steam energy lost by older boilers. It further increases energy-efficiency by being run at a lower temperature than what was possible for older boilers. The heat exchangers in older boilers were made of cast iron. If the water coming back to the boiler from the home’s heating system was below 140 degrees Fahrenheit, condensation was possible. Condensation would eventually destroy the heat exchanger. New designs allow and accept condensation, so can be run at lower temperatures.
What is outdoor reset?
The efficiency of your high-efficiency condensing boiler depends in part on the outdoor reset. The temperature at which high efficiency boilers run is based on outdoor temperature. When the temperature drops, the boiler sends hotter water through the house to compensate for your home’s greater heat loss in colder weather. As the outdoor temperature rises, the boiler sends out water at a lower temperature, and therefore receives back water at a lower temperature. Water returning to the boiler at 120 – 130 degrees Fahrenheit is perfect for condensation and the boiler works most efficiently with returning water in this range.
My boiler is still in good shape; should I replace it now or can I wait until it starts to fail?
While an “if-it-ain’t-broke-don’t-fix-it” attitude can be good, it might not be best when it comes to your home’s heating system. But if you want to increase energy efficiency without replacing a healthy boiler, there are some options available to you. Before you consider whether to replace your boiler or go with some type of retrofit, have a professional perform a combustion-efficiency test. A good option for an oil-burning boiler is an oil to natural gas conversion. Oil-burning boilers require more maintenance and cost more to run. According to the U.S. Department of Energy, from 2007 to 2012, it cost at least $700 per year to heat a home with natural gas, while it cost at least $1,700 per year to heat a home with oil. Whatever type of boiler you have, or how long you intend to use it, there is certain maintenance that should be performed regularly to keep it and the rest of your hydronic heating system working as efficiently as possible.
Should I hire a professional to perform regular maintenance on my boiler and hydronic heating system?
According to the U.S. Department of Energy, the following maintenance should be provided by a heating system professional:
• Check the condition of the venting system.
• Check physical integrity of the heat exchanger.
• Clean heat exchanger.
• Adjust controls on boiler to provide optimum water temperature settings for efficiency and comfort.
For hot water systems:
• Test pressure-relief valve.
• Test high-limit control.
• Inspect pressure tank, which should be filled with air, to verify it is not filled with water.
For steam systems:
• Drain some water from the boiler to remove sediments and improve heat exchange efficiency.
• Test low-water cutoff safety control and high-limit safety control.
• Drain float chamber to remove sediments to prevent low-water cutoff control from clogs.
• Analyze boiler water and add chemicals as needed.
• Perform maintenance on radiators, which will be different for one-pipe and two-pipe systems
If I replace my old boiler with a new energy-efficient one, can I get a government rebate?
Massachusetts has a Residential High-Efficiency Heating Equipment Rebate Program. To check your eligibility, visit http://www.masssave.com/residential/offers/gas-networks-hehewh