Your Boiler is Using Too Much Oil!
by Don Stoppe
Home boiler efficiency ratings are badly misleading. I have been a residential property manager and apartment house owner in Plymouth New Hampshire since 1984. We heat with oil fired hot water boilers and used 52,700 gallons of #2 heating oil last year. This is a reduction from over 64,000 gallons two years earlier. Our latest consumption reductions have been from changing to more efficient boilers. Current Annual Fuel Utilization Efficiency ratings (AFUE) do not represent real world gallons of oil used. I hope to influence a change in the way our government rates our boilers. Neither furnaces nor boiler AFUE ratings take into account how much heated inside air they send up the chimney but boilers have a much more serious problem with residual heat loss. The annual oil usage tells the truth.
I first realized efficiency tests had little to do with annual oil usage in 1986. We replaced two coal era asbestos covered steam boilers with two small Weil-McLain boilers at 19 C and D Russell Street in Plymouth New Hampshire. The annual cleaning efficiency test on the old beasts showed 72%-75% efficiency. The Weil-McLain boilers had AFUE ratings of 83%. My actual oil use dropped from over 900 gallons each to under 500 gallons each that next year. Over the next twenty years we replaced many old boilers with what we thought were modern designed boilers and realized substantial savings. In some cases we just replaced old 1725 rpm burner motors with 3450 rpm burner motors and saw a 10% oil use reduction.
In January 2009 I replaced a 2001 Peerless WBV-04 water boiler with a 2008 Buderus G215 triple pass Boiler at a triplex apartment rental at10 Winter Street in Plymouth NH. The Peerless boiler was rated at 85.1% efficiency by current AFUE standards. The Buderus is rated at 86% efficiency by current AFUE standards. We install our own heating systems now and were told to expect a 25% oil reduction. We made no other changes that year. Our annual oil consumption dropped by 22% with the change. In the 2007 - 2008 heating season we used 1882 gallons at this building. We used 1706 gallons 2008 - 2009 and 1468 gallons our first full year of 2009-2010 with the Buderus triple pass boiler. The AFUE standards implied a 1% savings.
When you look at the Buderus you see a 3" thick insulating jacket to keep the heat in. Hot flue gases pass over the heat exchangers three times to extract maximum heat from the fuel. The Peerless has a 1" insulation jacket. Exhaust gases pass over a much shorter heat exchanger surface.
The AFUE standards do not take into account whether the burner combustion air comes from the house creating drafts, or from outside. Almost all oil boilers require draft inducers or barometric dampers. This continuously vents air from the warm basement out through the chimney or flue pipe. It stabilizes the combustion air pressure in your boiler but drafts your warm basement air up the chimney all winter long. Compare this to leaving your fireplace flue open all year sucking heated air out of the house.
In 2010 we replaced 6 standard hot water boilers with Energy Kinetics System 2000 EK2 boilers at our apartment buildings in Plymouth, NH. These boilers do not require a draft regulator. They further purge excess stand by heat between run cycles to heating zones or the domestic hot water tank to be used in showers. The boilers have a thick insulation jacket. They are mounted on a stand that keeps the concrete cellar floor from acting like a heat sink. The heat exchanger is rolled steel which transfers heat faster than cast iron. Flue products pass over 10 feet of heat exchanger length before reaching the chimney. Combustion air is ducted directly from the outside instead of causing drafts by using inside heated air for combustion. The boiler only holds 4 gallons of water so there is less heat up time. The end of cycle thermal purge virtually eliminates boiler cool down losses. These boilers consume about 35% less oil seasonally then similarly AFUE rated boilers.
It is a little like the old car fuel economy standards. AFUE does not consider a real world situation. Stand by loss is not considered. Heated air in the home is sent up the chimney through the barometric damper and combustion air is not considered. The amount of heat the boiler loses into the cellar through contact with the un-insulated floor and from inadequate jacket insulation helps makes the boiler have a higher AFUE rating by current test standards. Actual seasonal fuel used is not determined and not even closely estimated with the AFUE rating. Boilers being tested for an AFUE rating are run at an artificially low boiler temperature of 120F-140F and under a high load to keep them from cycling off and on; that does not represent the realistic stand by loss. They run with less combustion air than found in real homes to reduce the stack temperatures for the test. Real home boilers operate at 180F to 200F supply water temperatures and they cycle on and off on even the coldest days. In real home applications there is adequate combustion air provided to prevent any sooting if conditions change slightly between servicing.
In real world scenarios a thick insulating jacket means less annual oil usage not more usage. Heat lost into the un-insulated concrete floor through direct contact is heat that does not go up the chimney so that boiler's AFUE rates higher by uselessly heating the ground. AFUE looks at chimney stack heat loss. Boiler manufacturers want high AFUE numbers so they minimize stack heat loss by dumping the heat into the basement through poor insulation and direct contact with the concrete. That heat needs to go into the living space. A manufacturer should be rewarded with a high AFUE rating for putting the heat where we need it.
The US Department of Energy is currently reevaluating AFUE standards. I sent this to Mohammed Khan at the US Department of Energy. He is overseeing this efficiency evaluation process through his Office of Energy Efficiency and Renewable Energy. I spoke with Mr. Khan and asked if there was resistance to changing the standards on how boilers are rated. I asked if there are large political players trying to prevent a change due to their personal interests. He said that there were parties strongly advocating all sides of this issue.
It is not in the interest of oil producers or distributors to sell less oil. Changes to AFUE standards to better inform the public would reduce their heating oil sales.
I am fortunate to have a great heating oil company that has helped me understand real world boiler oil usage. Fred Fuller Oil Company installs and services Energy Kinetic System 2000 boilers. Service Manager Bob White shares a wealth of information with customers on many years of fuel savings with these high efficiency boilers. Their web site offers $500 of free oil with a boiler install and estimates oil savings up to 40%.
You will see the most savings from a boiler change if you have a domestic hot water coil off your boiler. Also changing from a way oversized boiler to a proper sized boiler can save 10-15% from stand by heat loss. There are several good high efficiency oil boilers available on the market today. Knowing a reputable servicing installer is essential in avoiding problems. Oil dealers are starting to becoming more informed on the better boiler technologies. Unfortunately AFUE standards will mislead you to make a poor purchase decision.
This is a link to the Buderus boiler that saved me 22% over the Peerless boiler link below it:
Energy Kinetics AFUE comparison. http://www.energykinetics.com/afue.shtml
Fred Fuller Oil Company (System 2000 installer and servicer) www.fullers.com
The Performance of Integrated Hydronic Heating Systems Dr. T. Butcher, Y. Celebi, and G. Wei Brookhaven National Laboratory, New York http://www.bnl.gov/est/files/pdf/ButcherAachenPaper.pdf
Donald Stoppe is President of Stoppe Management Services, Inc.dba Campus Edge Apartments in Plymouth NH. He has a BS and MBA degree from Plymouth State University. Campus Edge Apartments rents apartments and houses to over 330 Plymouth State University students in Plymouth, New Hampshire. They have installed two solar hot water systems in student apartment buildings and have several more solar systems and high efficiency boiler systems planned for 2011. Don can be reached at email@example.com. His web site is www.CampusEdgeApartments.met
Please give us a call for the most current availabilities. (844)478-6773 info@StoppeManagement.com