Guide to Heating Oil Piping Defects & Leaks InspectAPedia® -
Heating oil piping errors, defects, leaks, and safety hazards
Heating oil piping leaks, loss of heat, oil burner puffback causes
Heating oil tank fill and vent pipe requirements
Where should oil line fire safety valves and check valves be located?
Where should the heating system electrical shutoff switches be located?
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This document describes defects in heating oil piping, filters, safety valves, and oil tank fill and vent piping. All of these oil storage tank and piping installation defects can easily be found by visual inspection.
Beyond the costly problem of leaky oil piping, this document lists other important safety or
oil-fired equipment operational defects in home and light commercial heating oil storage and piping systems.
This sample home inspection report language may assist home owners or home buyers in understanding
risks associated with both buried and above ground oil or other fuel storage tanks at their property.
The oil tank and oil piping inspection report language explains the need for action and indicates where
more information can be obtained.
Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
As Carson Dunlop's sketch shows, oil filler or vent piping that is too small can result in too much pressure in the oil tank during filling, resulting in a burst oil tank and serious oil leakage.
Oil tanks are usually filled under pressure (not by gravity like your car). We also do not like to see plastic oil piping used for these applications, out of concern that it may be broken, leading to a serious oil spill.
Carson Dunlop's sketch at left shows typical oil fill and vent piping details for an oil tank installed inside of a building. Usually these pipes are located together and against the building wall.
Sometimes we see that the oil filler pipe for an outdoor buried oil tank will be directly over the tank (and perhaps too close to ground level to keep water out), while the installer may have placed the vent pipe some distance away, against the building wall.
This may have seemed to be a neat job for the installer, but you should know that the oil delivery driver listens to the oil vent pipe to hear when the oil tank has been filled. Placing the vent line too far from the oil tank fill line is risky.
OIL FILL OR VENT PIPE CAPS LOST
As Carson Dunlop's sketch shows (above left) and as we show in Arlene Puentes' photo (above right), you are asking for water in the heating oil tank or insects clogging the fill or vent line (probably the vent line) if the caps have been lost from these pipes.
We've been informed of oil tank fill difficulties (perhaps even leading to a burst or oil tank leak) when insects clogged the oil tank vent pipe.
If the screen is lost from your oil tank vent pipe be sure to replace it to keep the wasps and mud-daubers out of this line. And be sure the screen on the oil tank vent pipe has not been blocked by painting over it - as we explain at OIL TANK PRESSURE for an explanation. this can cause an oil tank leak during an oil delivery.
NO OIL TANK VENT PIPE - Oil Tank - No Vent Pipe or Blocked Oil Tank Vent Pipe
Be sure that you can find a proper oil tank vent pipe. On occasion we find that a filler pipe was installed but no vent pipe was run outside. Improper oil tank venting such as no tank vent at all, a too-small oil tank vent, or a vent which is improperly installed, routed, or has become blocked, can cause a catastrophic oil spill in a building or outdoors at a buried tank. See OIL TANK PRESSURE for an explanation.
Oil fumes and even heating oil may spill into the building. The tank should be
vented to outside to avoid dumping noxious and possibly combustible or obnoxious fumes into
the living area.
OIL FILL PIPE EXPOSED - Oil Tank - Fill Pipe Exposed to Roof Drainage
Check to see if the oil tank fill pipe is in a location where roof drainage may fall directly on or into it.
Water in an oil tank can lead to loss of heat and costly related damage from that condition or
it can accelerate rust and corrosion from inside the oil tank, leading to oil leaks and a costly
environmental cleanup. The tank should be tested for the amount of water in it and if in question,
it should be tested for leaks. And protect the fill pipe and vent from water entry.
CAULK OIL TANK FILL & VENT PIPE ENTRANCES - Oil Tank - Caulk pipe entrances
You should caulk the opening where tank supply and vent pipes
penetrate the house wall, to prevent pest or water entry at this point. This is
an inexpensive item. This repair/maintenance item may be deferred.
OIL LINE EXPOSED - Oil Line Exposed to Damage
Check to see if the the oil lines are exposed atop the floor where they can be stepped-on. These flexible copper lines can be easily damaged, causing loss of heat or dangerous leaks.
The heating oil piping lines should be protected by means approved by your heating service professional. This should be an inexpensive
SINGLE HIGH OIL LINE - Oil Line Problem: single line routed high may lose prime
SERVICE NOTE: if an oil burner's fuel unit is served by a single line from a buried oil tank, or if the oil line is routed from even an indoor heating oil tank up high beneath the ceiling and back down to the oil burner, in some circumstances this installation may tend to lose prime in oil piping system, become air locked, or these events can lead to loss of heat and possible damage to the building from frozen pipes.
This problem occurs commonly if the oil tank is remote and buried (oil burner pumps don't have much lift capacity), or when an indoor tank is very low on oil. You should review this installation
detail with your service person.
See our discussion of check valves and the Tigerloop™ product at OIL TANK PRESSURE for alternatives to conversion of a single line to a two line oil supply piping system.
OIL LINE LEAKS - Oil Line leaks found - can lead to oil heat system puffback and loss of heat
Example of inspection report where leaks or drips are found in heating oil piping:
Caution: we saw a possible oil line leak:
... wet oily sections of piping at
... oil stains on the floor at
...
Oil leaks may be hazardous and also, as air may be drawn into the oil line when
the fuel unit is pumping, they can lead to improper system operation and even
loss of heat in the building.
It may come as a surprise but drawing air into the oil burner from a leak in the oil line can leave an air bubble in the oil burner nozzle. When the oil burner shuts down the pressure inside the nozzle area drops from 100 psi or more down to ambient pressure of just a few pounds.
The reduction in pressure causes that little air bubble to expand, pushing extra oil out of the oil burner nozzle where it dribbles into the oil heating system boiler or furnace combustion chamber. The next time the oil burner starts-up this un-burned oil residue forms a mini explosion - you may hear a sort of "bang" when the oil burner starts. This malfunction can lead to a serious puff back blowing soot into the home, or worse. This is an unsafe condition caused by what looks like a tiny innocent drip such as the one we show in our photo above.
This item should be checked/corrected by your
service person promptly.
SINGLE OIL LINE on a BURIED HEATING OIL TANK - Single oil line on buried oil tank risks lost prime, no heat
A single oil line was found coming from tank to oil burner.
Recommended practice is use of two pipes, for several reasons: avoiding loss of
prime, providing alternate pipe if supply pipe clogs, and reducing the lift
load on the pump.
Note: some experts recommend that the fire-safety valve for these systems be
installed ONLY on the supply line, with only a simple check valve on the
return line. This procedure reduces the risk of burst gasket at the oil pump
and spray of heating oil into an existing fire should a valve on the return
line close before the valve on the supply line during a fire.
HEAT TAPE HAZARD - Heat Tapes on heating oil lines are a Fire Hazard
Safety Recommendation:do not use electric heat tapes to keep fuel oil lines from
plugging during cold weather. Such measures are an obvious fire hazard.
HEATING OIL FILTER - NONE - No Oil Filter Installed on Oil Fired Equipment
If we do not find a heating oil filter installed on the system this is a defect that risks loss of heat.
Most modern oil heating equipment will have an oil filter installed, such as the one shown in our photo at left.
Notice that there's a heating oil leak below the connection to the filter outlet? This leak will suck air into the oil burner when it's running, leading to improper and possibly unsafe operation, risking a puffback.
Unless you find or the owner can point out a filter already in place, we recommend
installation of one - to be located at or very near the burner and "downstream"
of a fire-o-matic safety shutoff valve to permit easy service. Failure to
provide adequate filtering may lead to loss of heat and subsequent damage to
the building.
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Additional technical contributors & reference sources for this article are listed below.
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Carson Dunlop, Associates, 120 Carlton Street Suite 407, Toronto ON M5A 4K2Toronto. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Arlene Puentes, an ASHI home inspector in Kingston, NY, contributed the example photograph of an outdoor aboveground oil tank. Ms. Puentes can be contacted at ap@octoberhome.com
Dave Ferris - M&S Environmental Systems, Dutchess County, New York. Mr. Ferris was an
HVAC expert. Personal communication to DJF 1987. Remove the firematic or
fusible oil supply line valve on return oil-line side - in case of fire if this
one closes first the pump continues to run, blows its seal, and sprays oil all
over the fire. Proper installation is to have a fusible link valve only on the
supply side, and to install a check valve on the return line to prevent
back-siphonage from the tank.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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More Information on Building Diagnostic Inspections and Repairs
Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
Abandon a Buried Oil Tank, How To - Abandoning Commercial Underground Tanks, Russ Brauksieck, ASHI Tech. Journal, Vol.3 No.1 Spring 1993, P. 40-41 [Reprint]
Petroleum Bulk Storage J. Sibblies, NY State DEC, Advice to Home Owners and Home Inspectors about Oil Storage Tanks - summary from ASHI Chapter Seminar.
Septic Tank inspection, testing, diagnosis, repair
OIL TANK FAILURE CAUSES - Oil Tank Failure Causes - oil tank leaks are caused by corrosion, damage, soil conditions, other factors
TANK FAILURE RATES - Oil Tank Failure Rates - Oil Tank Leak Probability as a Function of Tank Age, Location, Condition, Soil Conditions and Other Factors
OIL TANK TESTING - How Oil Tanks are Tested for Evidence Leaks, of Current or Previous Oil Spills
Web Link Exchange: Contact Us to list your website or contact information for oil tank testing, tank corrosion research, oil industry experts
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