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Waste Oil Boiler
Waste Oil Boiler versus a Converted Oil Burner
The big difference is engineering. A waste oil boiler should be specifically engineered, designed and built to burn waste oil. It is built originally for a single use, to efficiently burn waste oil. Beware of waste oil boiler companies that take an oil burner and convert it into a "waste oil boiler". This stock boiler wasn't engineered and built to work well with waste oil.
Let's look at the major engineering reason. A standard pressurized fuel heater block heats the fuel to burn to a set fixed temperature. Waste oil (waste vegetable oil) will not burn efficiently with this configuration.
Several engineering principals need to be present including; pre-heating; how the fuel is pulled from the tank; compressed air passing through a specially engineered nozzle(s) to convert the fuel into a finely atomized mist to burn completely and very cleanly.
The Chambers
Stainless steel or steel burner chambers hype. It is a well-known fact that moisture is not what wears out a waste oil burner combustion chamber and/or heat exchanger. If moisture is not a major consideration then you need to look at heat conductivity. Many experts believe that the factor you need to really consider is the poor conductivity of heat from stainless steel. Steel is a fantastic heat conductor with makes a steel burner chamber on the waste oil boiler vastly more energy efficient.
These same experts state that the best waste oil boiler or waste oil burner utilize a triple-pass steel combustion chamber and heat exchanger. This gives the unit a big boost in heating efficiency. The single pass system is common with most heaters with a stainless steel chamber.
A steel chamber will last as long as a stainless steel chamber and the steel chamber has a superior heating efficiency rating. Makes you wonder why some companies make a big deal about having a stainless steel burner chamber in their waste oil heater or waste oil boiler.
Maintenance Claims
Don't be fooled by those "only needs to be cleaned one time per season" claims. How often you clean your waste oil boiler or waste oil burner affects the heating efficiency. It is recommended by most experts that you should clean the waste oil boiler or waste oil burner after every 50 hours of use. Some even recommend you even clean more often.
The truth is it is the efficiency of the waste oil boiler or burner that determines how clean of a burn you can achieve. It is this factor that will determine just how often you will need to clean your waste oil boiler burning equipment.
The Importance of Compressed Air
An air source needs to be piped into the waste oil boiler burner to atomize the waste fuel. Some units specifically engineered and built ground-up as a waste oil boiler will have a built in air compressor. You should not forget to consider the cost involved to pipe air into your waste oil boiler burner when making your purchase.
Efficiency = Stack Temperature
You've heard it before and we'll state it again. A higher stack temperature means a less efficient waste oil boiler burner. You also have a greater fire hazard potential with a hotter stack which can easily exceed 900 degrees. The desired stack temperature is under 500 degrees. A properly engineered stack will have double or triple walls. A single wall exhaust stack is legal to purchase but most local fire codes will require at least a double wall stack. Buy a single wall to save money (since it's legal to sell) will cost you more when your insurance carrier and local inspector makes you buy and install a double or triple wall stack. Do your homework up front and check your local codes.
BTU Rating
A quick rule of thumb for calculating BTU's for a waste oil burner both for a waste oil boiler and a waste oil heater. Take the gallons per hour (GPH) of the nozzle and multiply that by 140,000. One (1) GPH equals approximately 140,000 BTU's for a waste oil burner in the waste oil heater or boiler. This only gives the BTU's before the actual burn process. The after-burn rating is typically 80 to 90 percent depending on the unit.
Waste Oil Fuel Compatibility
Beware the claim from some manufacturers that their waste oil boiler burners can burn WVO, or waste vegetable oil. Some, if not most burners will not burn unprocessed purified waste vegetable oil. Make sure to read the fine print and make sure you don't need special waste vegetable oil for that make of waste oil boiler burner.