Water: Friend or foe?

As I talk to technicians and read the bulletin boards on various Web sites, I hear and see a lot of situations where technicians are complaining about dirty strainers, clogged oil lines and sludge. These problems are not new and will not go away by themselves. It comes down to fuel oil quality, tank maintenance and the need for proper filtration.

This month is the time that we historically get quite busy, and this year will be no different. We will see the start up of many systems that have been turned off since April. Over the summer, many tanks have been subjected to temperature and humidity, both which affect the oil that will be attempted to ignite after long dormancy ‘ not an easy task for an oil burner. The greatest enemy oil has in these tanks is water.    

Water droplets that are suspended in the fuel typically appear as a haze in fuel oil when pressurized. But not all water can be seen by the naked eye. Water that has gone into solution is also called dissolved water. This dissolved water can not be removed from the fuel by mechanical means and is not visible to the naked eye as haze. The concentration of dissolved water varies with fuel temperature and the relative humidity of the air coming in contact with the fuel (all summer), among other things. Water will also cause damage to fuel units. Only a water separator will remove water from fuel.

Water is necessary for microbial growth. Microbial contamination consists of organic debris created by fungi, bacteria and protozoa. Microbes gain entrance to fuel tanks from contaminated fuel supply sources, from airborne particulates through tank vents, from seawater and from condensation. Once the microbes gain access into the tank, they really have a party.

Microbes settle on tank surfaces and especially at the fuel/water interface. This is the distinct point where the oil and water contact each other. These microbes adapt to this environment very well and can occur if free water is present. Warm environments (like basement tanks, in ground tanks and outside tanks subject to the hot summer temperature) only help these bugs thrive. Sludge or mats of sludge can form, having a slimy or stringy consistency and appearing as a black, brown or dark olive color. This kind of contamination can quickly clog fuel filters, fuel lines and fuel units. The water must be removed if present. Also, the need for chemical treatment is evident.

After the water is removed, we then need to look at filtration. Many technicians and companies use a small oil filter on every job, regardless of whether it is a one pipe system or a two pipe system. One size does not fit all. Check out the specs on the different filters available and you will see what I mean. With today’s lower firing rate oil burners I recommend using a filter with a 10 micron filtration rating. Not all filters do this. A capacity rating of 45gph is typical; this is the amount of fuel the filter is capable of passing in an hour and is certainly within the range of any residential system. Some filters come with water separators as part of the package.

Let’s look at the amount of fuel going through that filter in a typical heating season. Typically, on residential heating systems, we will have a Suntec ‘A” fuel unit. This has a gear set capacity of 17gph when operating at 3,450 rpm. This means that 17 gallons per hour is going to pass that unit every hour the unit is operating. NORA, the National Oilheat Research Alliance, states that if a typical customer burns approximately 1,000 gallons per heating season, 1,000 gallons will be burned. For ease of the math, I will say each customer is burning 1.00 gallon of oil per hour of run time. If we are burning 1.00gph for 1,000 hours we arrive at 1,000 gallons burned.

If the filter is installed on a one pipe installation and we have a firing rate of 1.00gph, that means that 16.00gph is being bypassed inside the fuel unit since the gear set capacity is 17gph. It stands to reason that since the filter is located before the fuel unit, 1,000 gallons of fuel is passing that filter in a typical heating season.

Now, what happens on a two pipe installation? Using the same customer burning 1,000 gallons per year, the gear set capacity is still 17gph, but since we installed the by pass plug, we are no longer by passing inside the unit. We are now returning 16.00 gallons back to the tank every hour the unit is operating. That same little filter now will be passing 17,000 gallons of oil in a typical heating season. Wow, on one pipe we are moving 1,000 gallons, but on two pipes we are moving an incredible 17,000 gallons. Do you really wonder why that little filter gets clogged up on a two pipe system?

Looking at these numbers, I think we need to do something. We either need to use a larger filter that won’t clog as quickly, or we need to operate as a one pipe system. You need to determine the best option for your customers’ comfort and your company’s profitability and reliability. 

John Griffin can be e-mailed at johngriffin@tampabay.rr.com.  

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