As The Temperature Warms, It’s Time To Service Your Waste Oil Heater

Tis The Season..... The Servicing Season

If you have a waste oil heater, then you know that it is a major investment. To protect your investment you need to keep it operating at the best possible level.

The easiest way to do this is through annual service. The problem with many shops that own waste oil heaters is that they don’t take advantage of this protection because they believe their unit will operate just fine without any maintenance. This idea couldn’t be further from the truth!

Waste oil heaters burn waste oil, and while this observation may seem obvious to say, the effects may be less so.

The by-products of burning waste oil, emphasis on waste, is extremely corrosive. Which doesn’t go well with metal (which is what your furnace is constructed from). Not to mention this WASTE oil, isn’t the easiest for your system to manage from the tank all the way to the burner.

Point is this, waste oil takes it’s toll on the waste oil heater, and if you want your unit to run smoothly and last a long time, service is a must.

Let’s take a deeper dive into this and the reasons why you should have an annual service done:

1 – The Ash – The ash by-product from burning waste oil is highly corrosive. To make matters worse, many waste oil furnaces are constructed from “mild” steel. This steel is subject to corrosion. When the ash is left in the unit over the summer, the hot humid air mixed with the corrosive ash creates a recipe that will break your unit down much faster than it should. This leads to expensive components failing. In many cases these components can exceed 50% of the cost of a replacement unit. OUCH! Ash removal can add years of useful life to your waste oil heater.


Service To Do: The entire exhaust system needs to be thoroughly swept out to remove all of the ash. Then a full visual inspection of all the components that are heated and in contact with the ash for corrosion and damage.

2 – The Waste Oil – Even before it’s burned, waste oil is not the easiest thing to deal with. It’s inconsistent and full of sludge. This sludge can clog a system in several places that can starve the oil pump and affect the flow to the burner. It is important that you remember to check every year to ensure your strainers and filters are regularly cleaned.


Service To Do: Remove all 3 of the system’s strainers and clean them out. As well as running your tank down and having the sludge vacuumed out which will help prevent future sludge build up in the system.

3 – The Burner Assembly – Carbonized waste oil can affect all of the components in the burner assembly. This includes blocking and affecting the operation of the oil spray tip, ignition head, ignition transformer electrodes, and cadmium cell. The buildup of unburnt waste oil in any of these areas can affect the unit’s ability to run efficiently and without fault.

Service To Do: Complete disassembly of the burner assembly. This allows for full inspection of all of the components as they are typically covered in carbonized waste oil or suffering from some level of blockage. Then cleaning of these parts is completed as necessary.

4 – Safety Systems –  Most of the service involves a visual inspection component, however the safety systems and system faults cannot be inspected in this manner. Often times to check these systems you need to see them in action. And if you want the unit to operate without unexpected shutdowns, these systems should also be checked. Not to mention, any time you’re burning oil, safety should be a top priority.


Service To Do: Fire the unit and run it to full operating temperature so everything can be observed and adjustments made. This ensures the unit is running at or above manufacturers recommended standards to include the following:

  1. Atomizing air pressure
  2. Waste oil supply pressure
  3. Cadmium cell ohms resistance
  4. Warm air temperature = ambient + 80 deg F
  5. Flame appearance and length
  6. Exhaust gas stack analysis which includes:
    • Over fire draft
    • Draft at barometric damper
    • Stack gas temperature
    • Stack gas CO and CO2 readings
    • Previous (15) cycles digital instrument display and function data base review for failure trends

This through level of service may seem a little more expensive that some of the typical “bargain” services. However, as you can see, it will pay off in the long run. A thorough service will help ensure headache free and safe operation as well as extending the useful service life of the unit.

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