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CC500 owners manual (pdf)
CC500 brochure (pdf)
CC500
Combo oil & wood hot water boiler
The CC500 combination wood/oil boiler may be used when replacing an old boiler or when building a new home.
Click here for CC500 Installation. Click photo to enlarge.
The Benjamin line of Combination units, when used properly, will
increase the convenience and pleasure you receive from heating your
home with wood, and yet still give you the convenience and reliability
of heating with fuel oil.
Because of the unique Benjamin wood burning design, which will utilize
more of the BTUs available from each stick of wood, you will soon discover
that you can reduce the amount of wood that you use to heat your home.
How does the Benjamin CC500 Boiler do this?
In several ways.
- The unique combustion chamber.
- Hand welded steel construction.
- The "DUTCH OVEN" design.
- CC500 operational procedure.
1) The CC500's unique wood combustion chamber.
It's oval shaped.
It's lacks firebricks or wood grates.
It's thoughtful design and construction.
Hand welded, and constructed of 3/16" and 1/4" thick steel, the combustion
chamber is the heart of the unit. It measures 19½" in diameter and is 23¼" long.
As you may already know, smoke contains much of the wood's total energy, and it wants
to spiral by it's very nature. Benjamin has built a uniquely different combustion chamber
and heat exchanger that facilitates that effect. A conventional square combustion chamber,
or box frame heat exchanger restricts this natural flow. The smoke will rise up to the
corners and swirl around there, cooling as it does so. This cooling process allows
creosote and soot to form on these surfaces. They act as an insulator, and restrict the
ability of the combustion chamber and heat exchanger.
The oval design also eliminates the need for firebrick or wood grates. These were also
found to reduce efficiency. Wood grates will allow too much combustion air to enter under
your burning wood. Your wood will be consumed ineffectively and the heat will go up your
chimney, instead of into your home. Firebrick, in essence, will do the same thing. BTUs and
time will be lost as the unit is forced to heat the unneeded thermal mass.
Benjamin has a better idea.
Benjamin wants you to always keep a layer of coals and ash in the base of the wood burning
combustion chamber. These are to be used in place of the conventional wood grates or firebrick.
This will slow your wood burn down to a manageable level, allowing you to effectively remove
heat from all three of the stages of combustion, and it will allow the smoke to do what it wants to do naturally.
The wood and oil combustion chambers share a common heat exchange medium (water or glycol),
in a design that does not allow the wood smoke to ever come into contact with the oil burner.
This ensures that there is never an oil firing failure due to wood soot build-up on the burner
electrodes and nozzle. This enables you to truly utilize the convenience and reliability of oil heat.
OTHER POINTS:
Thoughtful design and construction.
The door to access the chamber is made out of cast iron. Benjamin is one of the few remaining
wood burning manufacturers that still utilize a cast iron door. They do this because the cast
iron will not flex the way a steel door will. This ensures a tight gasket seal and a reduction
in lost BTUs due to a constant air leak draft.
The wood combustion chamber is located above the oil chamber. This makes it easier to load and
clean. The wood shelf design further protects the oil burner from mishaps.
We are realists here. We know that someday (20 to 50 or more years from now with proper use),
the wood combustion chamber will simply become "worn out". Isn't it nice to know that Benjamin
has already planned ahead for you. Instead of going thru the cost of replacing the entire unit,
they have made it possible for you to just switch out the combustion chambers and heat exchanger
section, i.e., change out the guts of the unit. This can save you thousands of dollars down the road
when that time comes.
Another example of how Benjamin can provide comfort in more ways that one.
2) Hand welded steel construction.
The one piece, hand welded design of the Benjamin CC500 combination fuel boiler is constructed of
3/16" and ¼" thick steel. The 3/16" steel thickness extends all of the way out to, and includes,
the exhaust collar. Let's put it this way, the collar on the unit will probably be more rugged than
the smoke stack it connects to. Benjamin's safeguards the CC500's consistently high degree of product
quality, because each weld is individually inspected by the welder after it is created. Benjamin uses
thicker steel than many other manufacturers. Because of this, they have been able to extend their
product line's life span beyond that of which is expected.
Thanks to it's revolutionary one piece design, the Benjamin CC500 is classified as a
"single appliance".
This enables it to be connected to a single solid fuel chimney flue, further reducing your installation
costs. Maine code allows for this use, and insurance companies are agreeable to it as well.
3) The "DUTCH OVEN" design.
The "DUTCH OVEN" or "WET LEG" design is a concept where you completely surround the firebox with the
cooling water heat exchange medium.
This will:
- Eliminate the need for firetubes.
- Prevent damage from overheating.
- Increase efficiency.
Firetubes
Firetubes can be very effective on a conventional oil fired boiler like the Benjamin OB1000, but on a
wood burning boiler a firetube design can quickly evolve into a nightmare. Because soot and ash are a
constant part of the wood combustion process, firetubes can easily become dirty, or worse yet plugged
completely. This means that the unit will require constant attention and care to keep it operating
effectively. Because of its "wet leg" or "dutch oven" design, the Benjamin CC500 combination boiler
does not require firetubes. The "firetube wood combustion application" headaches are eliminated, making
it much easier to clean, and a delight to operate.
Damage from overheating.
Because both the wood and oil fireboxes are completely surrounded with water, the temperature of the
steel can never really exceed that of the water on the other side. This prevents a dangerous overheating
condition that can potentially damage your boiler, your entire system, or possibly even your home.
Increase efficiency.
If you were going to heat water on your stove top how would you go about it? I suspect that you would put
it into a container, and then set that container over a flame. You can't get much more efficient than
that...Unless you could figure out a way to contain the fire inside of the water, then you would have
something, as very few of the BTUs from the flame would be able to escape to the ambient air.
That is the idea behind the Benjamin Dutch Oven.
In fact it is so efficient, that it is currently under review for Energy Star certification. The only
combination unit in North America to do so.
4) CC500 operational procedure.
The Benjamin CC500 combination fuel boiler operates using one thermostat, but the unit itself requires
a triple aquastat, and a single aquastat.
The oil side of the system will be set at your "set-back" temperature. This is the temperature that you
want the boiler maintained at when you aren't around, typically this will be a low limit of 150°F and
a high limit of 170°F.
Now, let's say that you want to fire up the wood heat portion of your boiler when you get home from
work. You go down to the basement and start your wood fire. (If you want to preheat the chimney to achieve
a better draft for the wood fire, turn a wall t-stat up while you are loading the wood firebox. This will
create a demand from the boiler and will fire the oil burner.) Once you have a wood fire running that you
are happy with, go back upstairs and go about your normal activities. Your boiler was being maintained
within the oil set-points, but the wood triple aquastat, set at a low limit of 180°F and a high limit of
200°F, has taken over and will maintain these boiler temperatures by opening and closing the air draft
control on the wood combustion chamber. (The silver box and chain connected to the top left corner on
the front of the unit.)
When the wood fire goes out, the temperature of the boiler will start to drop. The wood aquastat will
be calling for heat, but there is nothing on the other end to provide it. The temperature inside the
boiler will continue to drop. When the boiler reaches the low limit oil set point of 150 degrees the
unit will automatically switch over to the oil burner and it will resume and maintain the oil aquastat
set-points, until you reload and light another wood fire.
These set points are fully adjustable and can be set anywhere you want them to be. With the automatic
switch over from wood to oil, you no longer need to worry about "rushing home to stoke the fire". The
Benjamin will take care of everything for you. Go out with your friends, stay late at work, relax, and
enjoy a slower pace to life. When you come home, the heat will still be on.
With a Benjamin in the basement, these are no longer concerns. You can remain toasty warm inside without the
fear of frozen water lines, as both the FS140 combination fuel furnace, and the CC500 combination fuel boiler,
when properly installed, can still operate effectively without power. They were designed to utilize gravity
flow convection, if the need arises.
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