Biodiesel and Biodiesel Blends
in Home Heating Applications
From B5 to B100
© Champlain Biodiesel LLC, 2006
This is a set of FAQ's
that should help you understand the basics of using biodiesel and/ or biodiesel
blends in a home heating furnace application. This list is far from complete and you are more than encouraged to scour
the web in search of more specific manufacturers warranty information,
scientific studies, as well as federal, state and local regulations. The document is solely the result of data compilation,
primarily from the AltFuelfurnace list serve on Yahoo, and no fact checking, testing, verification beyond that
has been attempted. Most of the advice
below then is purely anecdotal.
This web page is primarily
intended as a resource for homeowners who wish to use blends higher than the
standard B20 blend in their standard #2 oil burning furnaces. Furthermore this information has been mainly
gleaned from primary sources that were self posting information about their own
observations using primarily homebrewed biodiesel (non ASTM grade) and what
considerations and adjustments would need to be taken into effect. Commercial grade, ASTM fuel would have fewer
issues due to consistent fuel quality.
PROCEED AT YOUR OWN RISK!
Burner
Adjustments
Burning B100 in an
unmodified furnace could result in damage to the furnace and its inability to
ignite. Individuals have noted that various
small adjustments to their furnaces have enabled them to burnB100 with no
resulting problems. Individual furnace
makes and models may perform differently. You are advised to seek out professional licensed assistance before
modifying any furnace adjustments.
In general it seems that
most commonly things worked better by decreasing the air flow to their furnace,
although a small number noted they had to open the adjustment up, but there was
no one magic setting for all types of burners. Burner/ boiler make & model, chimney height, draft regulator
adjustment, fuel quality, blend level etc. all effect how the air band should
be set.
The best way is to adjust
the air for just the smallest amount of smoke and then add a little air just
past the point of zero smoke. The flame
gets shorter as the percentage of biodiesel is increased, becoming blue and
sparkly and some have noted it may be louder. This change in color may also effect the ability of the CAD cell to work
effectively. Reducing the air should bring the flame back to normal conditions.
As noted, higher levels of
biodiesl may turn the flame color from yellow to blueish due to its lower
luminosity, reducing the ability of the cad cell to work properly. This most commonly resulted in the cad cell
not seeing the flame and cutting out.
Ignition coil and
electrode condition and positioning is more critical with biodiesel than it is
with #2 home heating oil (HHO). It is
recommended that these be checked and measured by a qualified technician to
manufacturers specifications, as improper adjustment can lead to poor spark and
a furnace being unable to light. Poor
quality biodiesel can also led to carbon buildup on the electrodes, reducing
their ability to spark the gap between them. Biodiesel that has loosened the varnish in the existing fuel tank due to
its highly solvent qualities, may build up in the fuel line filter,
and eventually pass through the filter and either start to build up carbon on
the electrodes as well, in addition to clogging up the nozzle.
Nozzle size seemed to be
an important factor as it controls both the amount of fuel being used (GPH) and
the spray angle. Many users report that
a .75 GPH with an 80degree spry angle nozzle seemed to work well overall. Various burner manufacturers design their
burners to use either a solid, hollow, or semi-hollow nozzle and all have
different classification systems for these different models. Some users reported better luck using hollow
cones, but there was certainly no "one size fits all" nozzle due to the many
differences in biodiesel quality and burner design specifications. In general, the same make of nozzle, but at
a smaller size, possibly coupled with a higher pressure is the next step, possibly followed by a slightly more hollow nozzle.
Pump manufacturers are
slowly realizing that biodiesel is here to stay, and are slowly testing and
adjusting their pumps to deal with the materials compatibility issues that biodiesel can
present. Due to biodiesels ability to
slowly corrode/ eat/ melt/ degrade natural rubber found in pumps, seals, and
shafts, certain pump systems are at high risk of losing structural
integrity. This could result in
possible leaking or outright pump failure.
Webster makes the only pump on the market, currently, that
is built to handle B100. These pumps
are available for retail sale at numerous distributors listed on their website. Suntec has stated
on their web page (dated May 2011) that their pumps are compatible with a B5
blend and are currently testing for compatibility with higher blends. They are in the process of testing B30 and
expect the pumps to pass, while B100 will be evaluated in the future. Field
test samples of these are planned to be available soon. Riello apparently makes a B100 kit for their
burners, which is sold only in Europe.
Burners are individually
designed to work at certain pressure for maximum efficiency and longevity. Check with manufacturer's specifications
before adjusting things out of suggested range. Most users found that when the pump pressure was turned up into
the 125 - 140 range, they achieved a better flame and burn
characteristics. Because biodiesel has a
higher flash-point (temp at which it will ignite), making a finer mist improves
the chances of ignition by increasing surface area and thereby
reducing the time it takes for droplets to heat up to the flash point. Fuel quality will directly affect the flash
point
Seals top
Biodiesel will slowly eat
up pump seals and impellers containing natural rubber, especially with excess
methanol in it. The no hassle bet is to
replace seals with their Viton replacement.
Few problems were found
with transformers or voltage levels. Higher voltages (~14,000v) will certainly yield a better spark for
ignition. If a transformer is old and
not pulling the juice it should be pulling, a new one will only improve
efficiency and make for more reliable cold starts.
Maintenance
Out of spec fuel has shown
that there may increase carbon buildup on the electrodes, thereby decreasing
sparking abilities. Otherwise,
electrodes have not shown to be of any more of a concern with B100 than with
HHO with high quality biodiesel. Standard maintenance involving their checking their shape and angle per
manufacturers specifications seems to be adequate. Out of spec. electrode condition could lead to a poor spark and
possibly failure to ignite.
High blends of biodiesel
will loosen up the varnish that has built up inside of old HHO tanks. This "gunk" will then make its way through
the fuel line and arrive at the fuel filter. If the filter is not checked it will eventually clog up the filter, or
possibly push thorough and then clog up the jet nozzle. A basic, monthly, check of the status of the
fuel filter by a homeowner is the simplest way to avoid any issues. If the filter is looking "dirty" with the
varnish and rusty sediments that the biodiesel has loosened from the tank, its
should be thrown out and a new one should be used in it's place. Luckily, fuel filters are very inexpensive
and only cost $3-4. The amount of
varnish that is loosened up and sent through the system will depend on the
level of biodiesel blend in the fuel. There are reports that some users have found that by starting at a B5
level and slowly moving up to a B100 level over the course of 2 or so heating
seasons, the varnish will dissolve slowly enough so that it will not be a
problem.
Any fittings that are occasionally unscrewed (fuel line to
pump to check on pump status
) could develop leaks if small flecks of dirt,
grime, or metal become lodged between pressure fittings or within the threads
and create a slow leak that will simply create a minor/ annoying mess to clean
up. Best bet is to be careful when
removing/ unscrewing fittings to make sure that threads are not crossed and
dirt has not been introduced into the fitting anywhere. It is not recommended to apply any standard
plumbers teflon tape onto the fuel line AFTER the filter as strands may come
off and wind up in the pump assembly. Instead, apply a thin coat of pipe dope on the surface of any flare
fittings and or pipe threads. Make sure
the pipe dope is suitable for fuel oil.
Homebrewers will have to
decide if they wish to wash their fuel or not. Unwashed Bio will have leftover methanol, lye, methanol, soaps, and
unreacted mono and di-glycerides in it. Methanol is hygroscopic, and so soaks
up moisture as it sits in storage and also becomes more corrosive by forming
acids. Leftover methanol will greatly
increase the corrosive power of biodiesel on rubbers and other materials that
it is non-compatible with.
Storage length? top
Biodiesel should be used within six months for best
results. Biodiesel has not been in use
long enough to comment on longer storage periods. It has been noted by the National Renewable Energy Lab that this
can be extended with the use of standard petroleum additives. One source has noted that adding
anti-oxidants such as vitamin C or E will help increase the shelf life. Biodiesel should be stored in a container
that has as little air and water in it as possible. Any water that has found its way into the fuel will accelerate
the formation of algae, which will .
In brief, Teflon, Viton,
fluorinated plastics, and Nylon are compatible with B100 while nitrile rubber
compounds, polypropylene, polyvinyl, and Tygon materials are particularly
vulnerable to B100. Storage
tanks/fittings that contain brass, bronze, copper, lead, tin, and zinc may
accelerate the oxidation of diesel and biodiesel fuels and potentially create
fuel insolubles (sediments) or gels and salts when reacted with some fuel
components. Lead solders and zinc linings should be avoided, as should copper
pipes, brass regulators, and copper fittings.
The main text from the
National Renewable Energy Lab, Biodiesel Use
and Handling Guidelines notes that "B100
will degrade, soften, or seep through some hoses, gaskets, seals, elastomers,
glues, and plastics with prolonged exposure." Before handling or using B100, contact the equipment vendor or OEM and
ask if the equipment is suitable for B100 or Biodiesel. In some cases, the
vendor may need the chemical family name for biodiesel (i.e. the methyl esters
of fats and oils) to look up the information or even the exact chemical name of
some of the biodiesel components such as methyl oleate, methyl linoleate,
methyl palmitate, or methyl stearate. There have not been significant material
compatibility issues with B20.
If your existing equipment or
engine components are not compatible with B100, they should be replaced with
those that are. Materials such as Teflon, Viton, fluorinated plastics, and
Nylon are compatible with B100 (emphasis added). B100 suppliers and
equipment vendors should be consulted to determine material compatibility. Also
consult other B100 vendors in other regions of the country to see what problems
they may have experienced and what kind of replacement materials they are
using. It is advisable to set up a monitoring program to visually inspect the
equipment once a month for leaks, seeps, and seal decomposition. It would be
wise to continue these inspections even after one year, as the experience is
still relatively limited with B100.
Brass,
bronze, copper, lead, tin, and zinc may accelerate the oxidation of diesel and
biodiesel fuels and potentially create fuel insolubles (sediments) or gels and
salts when reacted with some fuel components. Lead solders and zinc linings
should be avoided, as should copper pipes, brass regulators, and copper
fittings. The fuel or the fittings will tend to change color and insolubles may
plug fuel filters. Affected equipment should be replaced with stainless steel,
carbon steel, or aluminum.
Tank Modifications
Primary solids tank
Due to the high solvency
nature of biodiesel, a large degree of varnish, or gunk will wind up being loosened
from the inside walls of any tank that has been used to store HHO for any
length of time, and make its way to the fuel filter. This rusty gunk will then clog up the filter if the minor, previously noted maintenance step of actually looking at it once
a month, are not followed. To lessen
the degree of sediment and gunk that accumulates in the fuel filter canister,
one recommendation has been to install a primary
solid catchments tank prior to the fuel entering the fuel filter
canister. This primary solids tank is
essentially another fuel filter canister that is installed just before the
existing fuel filter canister, and will allow any sediment and gunk in the
fuel, to fall out before it gets to the filter. Using a filter with a bottom drain as shown in the link, allows
you to drain out the sediments and varnish, without loosing the prime on the
pump, a great timesaver. This will also
allow a greater period of time to fall between main filter checks as much more
gunk will never get to the filter as it falls out into the primary solids tank
and is drained away, and not affect the fuel flow.
One method to avoid using
the gunk that will try to pass through the system is to place a tube up in the
drain nozzle that extends into the tank 2-3 inches. This will then draw in fuel from up off the bottom of the tnk
where the gunk will accumulate. At the
end of the heating season, drain off the fuel into a separate container and
dispose of the waste properly. If this
fuel is left to settle it will slowly layer itself and good fuel can be drawn
off the top of the tank. Bottom layers
of gunk, crud, and muck should be disposed of according to local rules and
regulations.
Some people have installed
a vacuum gauge in the line between the filter and the pump to keep track of the
filter clogging up. The filter may need to be replaced when soon after the vacuum reached
about 12" Hg. It has been reported. A simple filter check will alert a user to this same situation, however,
the vacuum gauge will allow the user to avoid having to take the filter off and
look inside the filter , possibly getting their hands dirty for simple checks,
although they will have to get dirty when changing the filter though. Standard latex gloves are a neat-nicks best
friend in that case.
Some users have even installed a nozzle heater to preheat
the fuel as an aid in combustion. When
working with SVO as opposed to B100 this is more of a concern and shouldnt be
a problem for use with biodiesel. Poor
igniting characteristics are more likely the result of poor quality fuel than
fuel temperature. That said, B100 will
gel at temps. in the mid 30s and so any storage tanks should be kept in a
heated space. Basements tend to be in
the 50s at least and so make excellent storage places.
Many people avoid most of
these hassles and just get a new, clean, fuel tank that wont pass any gunk
through to the fuel filter. Disposing
of old fuel tanks can be problematic, as junkyards are slightly hesitant to
take them as they could contain explosive vapors and ignite during crushing
type processes. Give them a call first
hand to see what issues may arise before removing your old tank. Make sure your tank doesnt wind up adding
to the visual blight on our landscape.
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With the current supply of petroleum being derived from unstable foreign sources and prices starting to climb, the general public and heating fuel dealers are seeking out alternatives. The practice of blending biodiesel with petroleum #2 heating oil is a new form of using two fuels that will help lower demand on foreign fuel sources, limit environmental pollution, and promote price stabilization.
The National Biodiesel Board has released information relating to blends from B2 to B20 that were used in home heating applications on their website. The NBB has a wealth of information regarding many different aspects of biodiesel and it is suggested that any homeowner considering using biodiesel peruse the materials and studies listed on that website and use them as a base of knowledge before beginning any use of biodiesel. An ounce of prevention, or knowledge in this case, is well worth the pound of cure, or cash, that it will take to buy a new furnace if things to bad. The following links would be advisable for review.
COMBUSTION TESTING OF A BIO-DIESELFUEL OIL BLEND IN RESIDENTIAL OIL BURNING EQUIPMENT
This FAQ may be copied with due credit to its origin. As noted above, there has been no effort to fact check or verify much of the anecdotal evidence that has been collected herein. Consider all this at your own risk and consult with a qualified technician before making any adjustments to your furnace that could result in a false start or a fire. A cold house is a bummer, a burned down house is a bit worse.