As we move into autumn, switching the heating back on is just around the corner. But don’t switch it back on without first checking your oil tank! A freezing winter morning is a terrible time to discover there’s a problem with your tank or you’ve run out of heating oil.
What are the essential checks you need to carry out?
Regular inspections
Heating oil tanks should be checked annually by an OFTEC-qualified heating engineer to make sure they are safe and in good working condition. But you should also carry out your own regular inspections. These can help you spot small issues before they become expensive repairs.
Look out for warning signs on the outside of the tank such as cracks or splits, bulging or stretching of the tank walls, rust on steel tanks, discolouration, patches of oil on the ground or discolouration of the grass and soil nearby. These can all indicate weakness in the structure of the tank, which could lead to leaks, potential environmental damage and costly clean-ups.
Check that access points are secure, sealed and properly fitted, paying attention to fill caps, gauges, vents and inspection lids. Loose caps or vents can allow insects, rainwater or dirt to get into the tank, which could contaminate your heating oil and damage your heating system. Double check that caps have been replaced correctly after every oil delivery.
Pipework failures are a common cause of leaks, so you should inspect the pipework and connections to the tank, paying attention to pipe joints, valves, filters and fuel lines. Look for small drips, corrosion, cracks and perished hoses.
Oil levels
The other big thing you need to check before winter is your oil levels. During the spring and summer, when heating oil is just used for hot water, inspecting your tank once every three to four weeks is enough.
As autumn approaches and you start to use your central heating every day, increase checks to every fortnight. Between November and March, you should inspect fuel levels weekly. And during prolonged freezing weather, checking your tank twice a week will give you extra peace of mind.
There are several ways you can check your oil levels and most heating oil tanks should have a gauge to help you. If you don’t have a gauge fitted, or you want to upgrade the type of gauge you have, Tanks for Everything stocks a range, including electronic contents gauges, float gauges, oil tank sight gauges and hydrostatic percentage gauges.
Different tanks have different measuring techniques, so we will run through the usual ones here. Most domestic and commercial heating oil installations have a mechanical float gauge, external sight tube, electronic ultrasonic monitor or rely on a manual dipstick check.
Mechanical float gauges sit on the top surface of the tank. Inside the tank, a plastic float sits on top of the heating oil, connected by to a dial on the exterior. As the level of the liquid goes down, the float drops, moving an indicator needle across a scale marked in fractions eg full, 3/4, 1/2, ¼ and empty.
Make sure you are reading your mechanical float gauge in good light, wiping away any dirt. Look at the dial straight-on at eye level to prevent distortion. Over time, internal gears or float arms can corrode or pick up dirt, making them less accurate.
Always gently tap the casing of the gauge before reading, because mechanical linkages can stick. If tapping the gauge causes the needle to drop suddenly, it is probably time for a replacement, because nobody wants to run out of heating oil unexpectedly in winter.
A sight gauge is a clear plastic or glass tube running vertically down the outside wall of a heating oil tank. The height of the oil inside the tube reflects the exact height of the oil inside the tank.
Many sight gauges have a push-button safety valve to prevent oil spills if the tube breaks. To check the oil level, press and hold the button for a few seconds to allow fresh oil from the tank to flow into the tube and stabilise. Check the height of the heating oil against the height calibrations printed on the tank frame.
Sight tubes can be read directly, but can get dirty or discoloured. Clean the tube before reading or, if it is getting too hard to read, request a replacement during your annual service.
Ultrasonic monitors, such as Watchman or Apollo systems, are standard on many modern bunded oil tanks or you can buy them separately and install them for older tanks. These devices are made up of a transmitter unit mounted on top of the tank and a digital receiver plugged into an electrical socket inside your house – up to 200 metres away for some models.
The transmitter unit measures the oil level using sound waves, which is converted into a visual bar chart on the indoor display.
To make sure your gauge is giving an accurate reading, regularly check the plug-in indoor receiver to confirm it has not lost connection with the outdoor transmitter. Keep the transmitter lens on top of the tank clean and free from bird poo, spiders webs or ice, which can all deflect ultrasonic pulses and trigger false low readings.
Electronic monitors need to be configured based on your specific tank height and shape during installation. If you’ve replaced your tank, but kept the same receiver, you must recalibrate the receiver or the display may be inaccurate.
Occasionally, whatever sort of gauge you use, the gauge display might contradict your expected oil consumption. If your heating system is working for several weeks during cold weather, but the display doesn’t change, you should treat this reading with caution.
If you suspect an inaccurate reading, carry out a manual dipstick check. Comparing the results of your dipstick check against your gauge reading will immediately confirm whether it is working properly. A manual dipstick check is the ultimate back-up check. When more sophisticated gauges fail or give conflicting information, a dipstick will give a true picture of your fuel depth.
To carry out a dipstick check, you need a clean, rigid wooden or composite measuring rod long enough to reach the bottom of the tank. You shouldn’t use anything metal, which could spark or scratch the inside of the tank.
Insert your dipstick slowly and vertically through the main fill point on top of the tank, until it makes contact with the very bottom of the tank. Remove it smoothly and in a straight line and check the wet line on the stick created by the oil. Measure the height of the mark using a ruler.
Don’t forget that, because tanks come in various shapes, liquid depth does not always indicate fuel volume. With rectangular and square tanks, fuel volume equates to fuel depth, so if the dipstick shows fuel height at 25%, it means fuel is at 25% volume. For slimline and vertical cylinder tanks, height and volume equate reasonably well, but it is very different for horizontal cylinder tanks or low profile tanks.
To convert dipstick measurements properly, consult the original manufacturer calibration chart supplied with your tank. These charts map every centimetre of fuel height directly to the corresponding litre capacity.
When to reorder oil
Late summer is a good time to order your heating oil and get your tank full. But, whenever you order it and however, you measure the oil in your heating oil tank, the most important rule is to reorder oil when your tank reaches 25% capacity. Waiting until your fuel drops any lower just puts you at risk of running out.
Ordering when the tank is still a quarter full allows for any seasonal delivery delays eg when companies get particularly busy during periods of extreme cold. And, by the very nature of rural properties, many are accessed by narrow lanes or tight gates, which necessitate smaller delivery vehicles. There may be an additional wait to get the right vehicle to safely deliver your oil.
Ordering early also prevents sludge disturbance in the tank. When oil levels drop below 10%, the suction line starts using fuel from close to the bottom sediment layer, which risks pulling sludge into line filters and causing blockages and even potential heating breakdowns.
For peace of mind, you might want to use a high-level alarm when your tank is being refilled. These alarms indicate when the tank is reaching its maximum safe level during filling, but before the tank is overfilled.
Carrying out checks on your heating oil tank in early autumn, before you start using the heating regularly, shouldn’t take long. But it can protect your home or business against unexpected leaks, running out of fuel and heating breakdown at the worst possible time of year.
By using clean and functional gauges, cross-checking readings with a manual dipstick when unsure, and placing new orders as soon as your oil levels hit 25%, your heating supply should be hassle-free all year round.
