Heating oil storage tank level gauges:
How to find the oil tank gauge? How to find out how much oil is in the oil tank. Heating oil tank gauge installation, reading, testing, repair guide: how much oil is in the heating oil tank? How accurate is the oil tank gauge? This article series escribes how to find, read, and test the oil gauge on a home heating oil tank.
If your oil fired heating boiler, warm air furnace, or water heater has stopped working, one of the first things to check is whether or not you've run out of fuel. If your oil tank is above ground indoors or outside it should have a fuel level gauge installed similar to the one shown in our photo.
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Oil tank gauges are pretty simple to find, recognize, and read. If your heating oil tank is above ground outdoors or indoors, look on top of the tank for a device similar to the one in the photos shown on this page.
If the heating oil tank has been enclosed for cosmetic or other reasons, it may be necessary to make an access door that can be opened to give a view of the oil tank gauge.
If the heating oil tank is inaccessible above ground or buried, remote oil level gauges are available. Installing a remote-reading oil tank gauge permits reading of the oil tank level from an readout device inside the building.
[Click to enlarge any image]
Shown at above left is a typical hinged-type oil storage tank float gauge. Other oil tank gauges may use a rigid vertical rod and moving float or an electronic oil level sensor method.
A float assembly inside the oil tank moves up and down along with the level of oil inside of the oil tank. As the float assembly moves up or down it pushes a metal rod upwards (oil level in the tank is going up) or lets the metal rod fall down (oil level in the tank is dropping).
On top of the metal rod is an indicator, such as the red plastic disk in our photo below. The red plastic disk forms a line inside the oil tank gauge, showing the level of oil in the tank.
In the photo of an oil tank gauge at above left the red disk is sitting above 3/4 - showing that the heating oil level in this oil tank is more than 3/4 full. The gauge is only close to accurate when the oil tank (round or oval in shape) is empty, half-full, and completely full levels. Oil tank gauges are more accurate on rectangular-shaped oil tanks and still more accurate oil tank measurement systems are available.
See OIL TANK GAUGE ACCURACY for details.
At above right the oil tank gauge installed on this Stewart Island, New Zealand oil storage tank reads oil tank level in cm - which works nicely to give an idera of how much oil remains if the tank's height is close to the gauge's operating range. The tank where this particular gauge is installed is shown below.
Well it's easier than you might think. On most oil tank gauges, the plastic tube that covers the actual moving gauge parts is just screwed into the cast iron base that holds the gauge assembly. Once in a while when we've wondered if our oil tank was really empty, or when an owner has reported that the oil gauge seems to "stick" we've done this simple test.
Unscrew the plastic cover by hand. Don't grab it with Vise Grips™ or you'll probably break the plastic. The gauge cover turns counter-clockwise to remove it.
If you did break the oil tank gauge cover it's not a catastrophe - the heating system will still work, but you should replace it before your next oil delivery because a broken or missing oil tank gauge cover could lead to a costly oil spill during an oil delivery.
Now that the cover over the oil tank gauge has been removed and set aside (where it won't roll under the oil tank and get lost), and presuming your tank gauge is not already sitting at the bottom of its range of travel (empty), just press the top of the gauge indicator rod downwards slowly and gently.
You will feel a little resistance because you're pushing a rod and float down into the heating oil inside tank. When you have pushed the indicator partly or all the way down, release it.
You should see the tank gauge rise back to about where it was before. This tells you that the hinged mechanism and float are still in place and that they are moving without obstruction.
If the gauge is broken, lost, or damaged, the entire assembly can be replaced by your heating oil technician. Remember that a heating oil tank gauge is not lab-grade equipment. It is not precise to the quart, probably not even to the gallon.
We have made a video of the procedure for testing an oil tank gauge and will post it here soon.
Here is a gauge on an outdoor oil tank. The red button resting at the bottom of the plastic tube to left of the galvanized tank vent pipe shows that this oil tank is probably empty.
This is a poorly installed oil tank, exposed to roof runoff, freezing temperatures, improperly closed vent opening, and more.
Watch out: Check to assure that the oil tank gauge is present, and that its protective cover is tight. Loose or broken oil tank gauges can cause spills during tank fill operations.
Your oil company can provide a stick, a folding rule, or even a string and weight that can be placed into an oil tank to locate the bottom of the tank and to determine the level of oil in the tank.
The depth of the oil in the tank is measured by marking the top of the tank on the stick or oil tank gauge, then placing the stick into the oil tank and withdrawing it. The oil level seen on the stick is compared with the distance from bottom of the stick (bottom of the oil tank) to top of the oil tank (which we marked on the stick).
In the old days people kept an oil tank stick that was already marked and calibrated to tell them how much oil was in their tank. Today if we use a folding measuring rule or a generic "stick" to "stick the oil tank" to check oil level, we need to know the volume and shape of the tank as well as the depth of oil on the stick in order to calculate the number of gallons in the oil tank accurately.
In the photo our client is discovering a surprise buried oil tank at a farm we were inspecting.
Some buried oil tank systems use an oil tank gauge that measures oil in the tank and gives a reading at a remote location such as indoors near the heating boiler - which is pretty convenient in nasty weather.
Our photo shows an antique gauge used with a buried oil tank. Modern remote oil tank gauges include sensors which provide an LED or an electronic indication of the level of oil in the buried or remote oil tank.
But roughly, the oil tank stick procedure can tell us if the tank is half full, 3/4 full, or nearly empty.
This topic has moved to OIL TANK GAUGE ACCURACY
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The plastic cover that covers (shows the 1/8 markings) the gauge of my oil tank broke/cracked.
Do you know where I can get a replacement? - Robert Muller
I have got a Worcester Camray 5 which is located in the garden. I had an indoor plug in oil level indicator but it has gone missing - where can I get a replacement one please. - Karen Gallant 6/27/12
The plastic part that covers your oil tank gauge is called the gauge vial. You can get one from a local oil heating equipment parts supplier or online. - Reader G.C. [Thanks GC] .
Karen the Worcester Camray 5 is a discontinued oil fired heating boiler. I don't know about the oil level indicator you cite - but if it is a device mounted on your oil piping or oil tank, I would imagine your oil heat service company can install a generic replacement.
Question on a fuel oil tank gauge: 275 gallon outside, vertical, 8 years old, in good repair. Sees Maryland winters.
Last spring, my oil supplier left a note that the standard float gauge did not work. In summer, I removed and cleaned the plastic dial cover with Mineral Spirits and a bottle brush
It was heavily coated inside, almost opaque, a bright red hardened gum. Then gently pushed the float down into a full tank, cycled this slowly several times full range, and it worked for almost a season. Now with the last fill up, it again is stuck on empty. Is there a gum in No 2 FO? Does it splash up and glue the float mechanism? How often does the gauge need maintenance? Mr. R.L. Hails Sr. P.E. 2/25/2012
Oil tank gauges often work reliably for decades and do not require maintenance. On occasion if a gauge stops working it's possible to free up stuck parts by simply moving the gauge operating parts a bit. If that doesn't work, replace the gauge.
I have a float gage (319 gallon indoor oval tank), the tank went empty and was filled with 200 gallons however the gage did not return to show approximately 3/4 full. Is it because there is liquid sitting on top of the float gage? If so, is there a way to correct this so the tank reads accurately? - Ian 8/7/12
The float arm may be bent or the gauge sticking. You should be able to carefully disassemble, remove from tank, un-bend, un-stick moving parts (or replace them).
If your oil tank gauge looks like the one at the top of this page, try first unscrewing the plastic cover and press down gently on the gauge top indicator - the whole assembly will move and you're pushing the tank float and arm up and down inside the tank - sometimes this will free up the assembly without further ado.
Oil won't be delivered unless the tank gives out a whistle, please explain since I'm new at this. and what can I do. Thanks. - Felix S 11/12/12
The oil tank whistle is a device at the top of the oil tank that emits a sound that lets the oil delivery truck driver know when the tank is full. It has nothing to do with the transfer of oil from the oil tank to the heating oil burner.
(Dec 20, 2012) Joe said:
I recently bought a forclosed home that was built in 1957 with oil heat. The house is a 1700 sq feet brick ranck home. The oil was at 5/8 full when I moved in. I have been working on it for 4 hours a day at 60 degrees. I turn it down to 50 degrees when I leave. In one week I checked the gage and it was at 3/8s of a tank. I cant imagine it sucking that much oil. It is really bothering me how unbelievable ineffecient it is. Does anyone have any advise?
(Jan 1, 2013) Darlene said:
I had 1/2 oil in my tank,I then got 100gal and the gauge stayed at 1/2,so I went and got a new gauge and it seems to stay at 3/4. It does not more?
(Jan 1, 2013) Karen said:
Our oil tank has just gone a sliver below the 1/4 mark. Our landlord has always told us never to let this happen. Due to the holidays and financial difficulty, we cannot get oil for 3-4 days from today(12/31). Is something terrible going to happen? Im very worried. This is the first time in 10 years this has ever happened. Any thoughts?
(Jan 4, 2013) todd said:
joe, your furnace is working harder to get to 60 from 50 than say from 56 to 60 ,leave it a higher setting than 50 or try smaller lncrements
(Jan 4, 2013) todd said:
Darlene… as stated above gauges are not 100% correct 3/4 is the safe fill level,in 10 years as a oil truck driver a gauge that reads 1/2 will take only 100 gallons, your tank is at max capacity
(Jan 4, 2013) todd said:
Karen you can put 5 to 10 gallons of diesel fuel to last 1 or 2 days (20 to 40 dollars)
(Jan 4, 2013) Stan said:
My oil tank was half full and yesterday I had it filled to the max. This morning the gauge reads empty?
(Jan 4, 2013) todd said:
Stan check for leaks then check for sticking gauge
(Feb 26, 2013) Robin A said:
I have a 275 G tank without a TLI. The 1.5" vent line has a capped end that I stick a stick in to see what the level of oil is. The top of the capped nipple is about 10" above the top of the tank. Can I just stick a TLI in this hole? I have found a couple examples that I think will work such as the Krueger Sentry Galvanized Direct Reading Gauge. It indicates it has a "tank depth" of 6" and I'm not sure what that means. I also found a similar gauge that has a "tank depth" of 10" - not sure what that means either. Can you help? Thanks!
Most likely the oil tank fuel level gauges you describe, when they refer to a "tank depth of 10" " are saying that the gauge can measure oil level in a tank at depths anywhere *between* 10" and a deeper level, typicalliy 144".
You need room above the tank to insert the new gauge and you'll be all set.
There are various LED and other electronic oil tank fuel level gauges that permit remote reading of the level of oil in the tank, but all of them require some sort of sensor or float inside the tank where the oil level will be monitored.
Krueger, the company you mentioned, provides an "LED at a Glance" LED Clamp-on device that will convert the position of the float gauge indicator into an electronic signal of oil level that can then be read by a remote display - that feature may not be one you need.
Contact Krueger directly at
Krueger Sentry Gauge
1873 Siesta Lane
Green Bay, WI 54313
Telephone: USA 1-920-434-8860
(Sept 9, 2014) Rob R said:
the gauge vial on my tank is broken/missing. The sending unit is working perfectly so I am able to guestimate the gallons of fuel in my tank. I have searched for a replacement vial online but they all are threaded vials. Mu issue is that my gauge is held onto my tank with four small screws. You have a photo of the type that I have as the first picture under your " How do we know that the oil tank gauge is working?" paragraph. There are no threads on the gauge mounting hole. Can you provide any insight on how to replace this type of gauge or vial?
It may be most simple to replace the entire oil tank gauge assembly rather than waste a lot of time looking for an obsolete part. Krueger, mentioned below sells a variety of oil tank float gauges and tank bushings that will probably work fine for you.
Or use our email found at our CONTACT link and send me some sharp photos of your gauge and I'll see what I can find for it.
J. Ross Keys said:
If a supplier overfills a oil tank in the basement of a dwelling and the fill pipe is full, is it possible that the hydraulic head of the liquid above the gauge would leak oil? In other words if a plastic level gauge is installed correctly, what pressure rating are they designed to hold under manufacturing testing?
Definitely. Oil tank gauges, depending on the type and design, can leak if an oil storage tank is overfilled. I think that the leakage will be more severe during fill-up as the tank is being filled under pressure, applying greater oil pressure to the gauge and its seals than just that from the head of oil remaining in a fill pipe afterwards. Examples are in the article above.
(Oct 10, 2014) Anonymous said:
What kind of valve to use to prevent air bubbles in the fuel line
(Nov 26, 2014) Anonymous said:
we have two 275 gallon oil tanks. the furnace was not coming on, technician blew out the line, and after a while, some oil came in.
However, he said that the crossover line between the two tanks must be getting clogged, as the oil is not flowing freely from one tank to the other. He measured the front one, said it had 18 inches, the back one seems to be full or close to full. The way the tanks were installed it is almost impossible to reach the valves on the bottom of the back tank, the crossover line etc. He says they need to empty the tank, and turn them to both face front, so that a person could get to all the valves etc. Is this really the only way to go?
Good grief what a lot of trouble, and what a thoughtless original installation. Unfortunately when blowing out an oil line cannot adequately clear it, replacing the line is a typical solution, along with use of an oil additive to break up sludge, along with sludge removal from the tanks along with increased filtration at the oil burner to avoid clogging by the sludge released by the whole procedure.
It's just about impossible to install a new balancing line between the two tanks connected to tank bottoms without first emptying the tanks. If going to that much trouble (emptying tanks) I'd look at sludge removal at the same time, or even tank replacement if the tanks are quite old and rusted thin since much of the cost is in the labor.
An alternative MIGHT be to close off the clogged lines and install new, larger diameter oil lines coming off of the tank tops. But some clever piping may be needed to assure that both oil tanks are used when tapped from the top
(Jan 3, 2015) Anonymous said:
One solution that worked for me is to install an oil filter housing without filter in line before your oil filter. This is the lowest point and will gather all the sludge and water. This way the sludge comes to you. The only cost is the housing and a gasket. Techs refer to this method as a sludge pot. Hope this helps.
(Jan 28, 2015) Anonymous said:
oil tank vent alarm not working, what could be the cause?
Tank is not filled to the vent
The alarm is clogged or has lost a part
Insect clogging in the vent pipe
(Feb 13, 2015) Anonymous said:
I asked the oil man to fill my tank that read 1/8 tank. When he came he pumped 110 gal and it indicated full to delivery man. The guage read 1/2. They told me that foam formed when new oil was put into tank that caused it to indicate full and stop pumping. I've never heard of such a thing! Any comment?
What you describe is not something I've come across but it has been described as an effect that can occur if there is water contamination in the oil storage tank; during delivery the incoming oil, delivered fast and under pressure, can stir up water and form foam - this can also clog up the heating oil piping, filter, burner, and lead to loss of heat.
I'd ask the oil company to check oil tank water level, remove excess water, and go from there.
I'd also check - if you can - about just what was being delivered to you - if your oil tank didn't have much water in it before then water could have come in a bad delivery. I've seen this happen if the oil truck is filled from a depot tank that is low on oil, has water in that tank bottom (which is normal) and is itself stirred by a depot delivery while the oil truck is filling.
Experts have written about this
(Mar 2, 2015) Anonymous said:
what are the correct positon of the two ball
levers on top of outside oil tank
Sorry Anon you'll have to use our contact link found at page bottom to send me photos - I 've no idea what you're asking about;
Send me some sharp photos and we can comment more usefully.
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