Buying heating oil: order size, timing and tank management

Why the last quarter of the tank matters

Every oil tank accumulates a layer at the bottom: water from condensation, sediment, degraded fuel components, and in steel tanks, rust. In normal use the outlet draws from above that layer and it sits there undisturbed.

As the level drops, two things happen. The remaining fuel is closer to the layer, so ordinary movement stirs it. And the outlet begins drawing from nearer the bottom. Run the tank right down and you draw the layer straight into the supply line.

The consequences arrive over the following weeks rather than immediately: blocked filters, water reaching the burner, a blocked nozzle, and occasionally a damaged pump. See running out of oil.

Order size

There is a straightforward economy of scale: the cost per litre generally falls with order size, because the delivery cost is spread over more fuel. That argues for the largest order your tank will take.

Against that:

• Tank capacity is the hard limit, and you should never be ordering right up to it – the tank needs headroom.
• Cash flow. A full tank is a substantial amount of money sitting in the garden.
• Long storage. Kerosene stored for very long periods can degrade, and a tank that turns over slowly accumulates more water through condensation.
• Minimum order quantities. Most suppliers have one, and a small emergency order attracts a premium.

For most households the practical answer is to order enough to fill the tank from a quarter, which means one substantial delivery rather than several small ones, and to time it well.

Timing

Heating oil prices move, and we do not publish forecasts or price data because we have no licensed source for it and a plausible-looking number would be fiction – see what things cost for our position on published figures generally.

What we can say without inventing numbers is about demand and logistics, which are observable:

1. Cold snaps create demand spikes. When the temperature drops sharply, everybody orders at once. Lead times extend from days to weeks, and that is precisely when you cannot wait.
2. Winter is the busy season, and summer is not. Suppliers have more capacity outside the heating season.
3. Emergency deliveries cost more, where they are available at all.
4. Lead times are longest exactly when you need it most. This is the single most important practical fact about buying heating oil.

So the operational advice is simply: do not be the person ordering during a cold snap. Order ahead of the season, keep a reserve, and you take the timing problem off the table entirely.

Buying groups and syndicates

Oil buying groups are common in rural Norfolk and they work on a simple principle: a number of households in an area combine their orders so the supplier delivers a large volume on one round, and the group negotiates on that basis.

Worth knowing:

• They are often organised through a parish council, a village association or a local group, and many have run for years.
• The order is placed on a schedule, which means you need your tank to be able to wait for the next round – another argument for a reserve.
• The saving comes from volume and from efficient delivery rounds, both of which are real.
• You are still dealing with a supplier for the delivery itself.

If you are in a village and there is a group, it is usually worth joining. If there is not, it is the kind of thing a few neighbours can start.

Tank management through the year

1. Fit a gauge you can trustFloat and sight gauges stick and mislead. An electronic level gauge with a low-level alarm is inexpensive and removes the entire run-dry problem. If your tank is at the bottom of a garden, one that reports to a receiver indoors is worth having.
2. Know your consumptionRoughly how many litres a week in winter, so a quarter tank is a number of weeks rather than an abstraction. Your delivery records tell you this.
3. Order at a quarterAlways. In winter, earlier.
4. Fill before the seasonA full tank in September is a household that does not care what happens to lead times in January.
5. Keep the vent cap on and the fill cap secureRain in the tank is where the water layer comes from, and an unsecured fill cap is an invitation.
6. Let a delivery settle before firing upAn hour or two, so anything stirred up by the fill can drop back.
7. Check the filter bowl at each serviceWater there tells you about the tank. Act on it rather than just draining it.
8. Look at the tank once a yearTen minutes in spring – see eight signs an oil tank is near the end of its life.

Security

Heating oil is valuable, portable and stored outdoors, and it gets stolen – particularly from rural properties where a tank is visible from a road and the house is not overlooked.

• A lockable fill cap is cheap and it is the basic measure.
• Siting matters. A tank out of sight of the road, or within view of the house, is a less attractive target.
• Lighting and alarms. A level gauge with an alarm that reports a sudden drop is genuinely useful, because most tank theft shows up as an unexplained loss rather than as an obvious break-in.
• Avoid advertising the fill. A tank that is always full immediately after a visible delivery is a known quantity.
• Check your insurance. Cover for stolen oil and for tank damage varies, and it is worth knowing what yours says before you need it.