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What’s the best bunded oil tank for domestic home heating?

Posted 7th January 2019

We’re often asked what the best bunded oil tank for home heating oil is. That’s a broad question and it’s why we offer a free site visit to assess your oil storage requirements.  Every homeowner’s requirements are different.  However, there are a few common factors for choosing the best oil tank for you and your heating system.

What size oil tank do I need?

OFTEC guidelines suggest a tank size with enough oil capacity to last a year, although not many customers want to store that much fuel in their garden. Below is a table of typical sizes we use, but each household will consume heating oil at a different rate due to individual use.  It’s worth considering whether you need extra oil for a range cooker, i.e. an AGA, Rayburn or other oil fire range. An AGA typically uses seven litres of fuel per day, that’s 49l per week, approximately 2500l per year.  So AGAs affect oil consumption even when they are switched off over summer.  Perhaps you could use a smart option to help you keep track of that oil?  We can also provide fuel levels in the form of a Watchman Sonic that lets you check from the comfort of your home.

Oil tank size and typical properties
Typical house size
Slimline Tanks
Vertical Tanks
Horizontal Tanks
650L – 1000L
1-2 Bedroom House
Holiday Cottages
Park Homes
Deso SL650BT
Harlequin 650HQI
Deso SL1000BT
Harlequin 1000HQI
1000L – 1550L
2-3 Bedroom House
Holiday Cottages
Small Commercial premises
Deso SL1000BT
Harlequin 1000HQI
Deso SL1250BT
Deso V1230BT
Envirostore 1300EVB
Deso V1340BT
Tuffa 1400VB
Harlequin 1450HQI
Deso LP1200BT
Deso H1235BT
Envirostore 1300 
Harlequin 1400HQI
1650L – 2500L
3-4 Bedroom House
Commercial Premises
Village halls / Churches
Titan SSL2000 
Deso V2455BT
Envirostore 2500EVB
Titan ESV2500 
Harlequin 1650
Deso H1800BT
Envirostore 1800EHB
Titan ES1800
Harlequin 2000HQI
Deso H2500BT
Titan ES2500BT
Envirostore 2500EHB
Harlequin 2500HQI
Larger homes – high demand
Schools, Village Halls
Commercial premises
Titan ESSL4000
Deso V2455BT
Envirostore 2500EVB
Titan ESV2500 
Deso V3500BT
Titan ESV3500
Tuffa 3500VB
Deso V5000BT
Envirostore 5000EVB
Harlequin 5400EVO
Tuffa 6000VB
Envirostore 8050EVB
Deso H2500BT
Titan ES2500BT
Envirostore 2500EHB
Harlequin 2500HQI
Harlequin 3500HQI

Tank size and shape

As you can see from the table, there is a large choice of shapes and sizes to choose from.  All the above examples are from our plastic bunded oil tank range, from leading manufacturers.  We also offer a range of oil tanks with steel bunding.  This flexible manufacturing method allows for bespoke sizes and capacities to suit any requirements.  

Atlas Tanks, among others, provide us with Slimline tanks.  In short, they are designed to be narrow and tall so they are best suited to installations where space is a premium.  These are also typically used alongside a garden path or areas with narrow access like garden gates.  This tank shape works well behind a garage or along a boundary.  Likewise, 1000l to 1550l tanks is a good replacement for older, 300-gallon single skinned tanks.  These older tanks were 2′ wide, 4′ high and 6′ long.

Vertical shape tanks, with a round footprint, offer the best value per litre.  They also require less moulding material due to a cylinder’s inherent strength, these vertical bunded tanks work well in corners and new installations.  As a result of their strong design, vertical tanks can be manufactured in capacities from 10,000 litres up to 15,000L for oil storage.  They also perform equally as good in smaller sizes.

Horizontal tanks, square in general shape, are the best choice in the 1650L – 2500L range, replacing the old, steel, 600gl tank. 6′ x 4′ x 4′.  Ideal for larger houses with enough outside space for a tank of this size.

Plastic vs steel – which is the best bunded oil tank material?

The majority of tanks we supply are of the plastic bunded variety and most of our domestic heating oil storage tanks use a medium-density polyethene (MDPE).   The inner tank is rotationally moulded as a single piece with no seams or joints.  It is then placed into a 2 part, outer bund and the bottom half of the bund must have at least 110% capacity of the inner tank.  Finally, the bund top is then bolted to the bottom half of the bund to complete the tank as an integrally bunded unit.

The fill point, inspection hatch and level gauge are installed on the inner tank.  This protects them from accidental damage, the environment and keeping them out of direct sunlight.  The outer bunded top has a large lid which conceals access to the inner tank and fittings.  These bunded fuel tanks often come with up to 10 years warranty.

Steel tanks have their own benefits too, see more in the comparison table below.

Oil tank standards

Tanks designed for sale in the UK should have a ‘Declaration of Conformity’ from the manufacturer for their tanks.  The primary (inner) tank should also have a CE mark if it was manufactured to EN13341.  OFTEC produce their own standard for both plastic and steel tanks; OFS T100 for plastic tanks and OFS T200 for steel tanks. But all OFTEC approved plastic tanks will have an OFCERT number.  A list of approved manufacturers and each tank is also on the OFTEC approved list.

What’s the best; bunded oil tank or single skin?

A bunded heating oil tank is a tank within a tank.  Their construction is either steel or plastic and some are steel/plastic hybrids.  Bunded tanks offer the best protection from the environment and condensation because of the insulation provided by the air gap in the bund.  Moreover, other advantages include inner tank weather protection, prevention of water ingress and other organic garden material like leaves, insects and spiders.  Lastly, tank filter kits and pipework, feeding the boiler, are often blocked by these foreign contaminants.

Single skin plastic oil tanks are only fit for areas when an existing bund is in place.  As a result, they are significantly cheaper but come with a fair amount of risk.  With no built-in protection from oil leaks, for example, the clean up can become costly which would eat into your savings from purchasing a single skin tank.

Oil storage risk assessment

First of all, any tank installation must comply with current building regulations in the OFTEC standards.  This also includes the physical location of the tank and its distance from certain risks. Secondly, this part of the installation process is the ‘Oil Storage Risk Assessment’ which covers environmental and fire risks.  OFTEC form TI/133D Oil Storage Risk Assessment is used prior to installation to record and identify the risks involved with the proposed installation.

Environmental considerations:

  • Is the tank capacity over 2500L?
  • Is there a:
    • river, stream or watercourse within 10m?
    • drain, manhole or open drain near the tank?
    • a well, borehole or spring within 50m of the tank?
  • Is the tank over hard ground thus enabling a spill to enter a watercourse or drain?
  • Can the vent pipe also be seen at the fill point (extended or remote filling of the tank)?
  • Are there any other further hazards unique to the location?

If the answer is ‘yes” to any of the above questions then a bunded tank will be required.

Consider the fire risks; will the tank be within:

  • 1.8m of a combustible structure? (typically this can also include sheds, wooden garden builds and summer houses, wooden garages etc….)
  • 0.76m of a combustible boundary, this includes hedges, wood fencing, open link fencing and other materials which are not fire resistant.
  • 1.8m of an opening in a building, including doors and windows in houses, garages and other buildings.
  • 1.8m of the boiler flue outlet/exhaust?
  • 600mm of internal fences, trellis and combustible material.
  • At least a 300mm fire-resistant base around the tank.
  • 1.8m of any combustible roof eaves or thatch.

In this case we install fire barriers or screens.  These include any material with a 30-minute fire rating.  Some examples are cement particle board, 4″ block work walls and other fire resistant material like rockwool panels.  Their specific fire resistant design stops the transmission of any potential fire getting to the tank.

Can anyone install an oil tank for domestic heating?

Installation of an oil storage tank is not generally considered a DIY job.  Especially if you are replacing an existing tank with kerosene heating oil still inside.  Transferring fuel from an old tank to the new one should also be undertaken by a professional.  This way the redundant tank can also be taken away to be recycled.  In order to install an oil tank, the installer will also need to be registered and qualified.  Either with a competent person scheme such as OFTEC and have an OFTEC 600A qualification.

All domestic oil storage tank installations need to comply with Building Regulations.  However, in England and Wales, OFTEC registered technicians can self certify their own work without involving Local Authority Building Control.  However, you can choose to use someone who isn’t registered with a ‘Competent Person’ scheme like OFTEC.  In that case, you will have to obtain a Building Control Notice and arrange for an inspection.  These are costly and time-consuming and similar rules apply in Scotland where you may need to apply for a warrant.  More information can be found on the Government website.

Most installations don’t require planning permission.  Unless the overall height is above 3.5m or the tank is going to be located nearer to a public highway than the existing house. However please check with your local planning office if you are in any doubt before installation starts.  Also, check any local regulations and by-laws that may place restrictions on an installation. An example would be Areas of Outstanding Natural Beauty, most of these require bunded tanks regardless of the oil storage risk assessment.

Our most popular oil tanks

At Tank Services, we also install a wide range of tanks as you would expect.  This is our selection of the best bunded oil tanks, above all these tanks fit best in gardens and tight spaces. Hence why we use them so frequently.

TankImageWhy we love itDimensions 
Deso SL1000BT1000 litre slimline Bunded Oil Tank Deso SL1000BTWith its slim design and compact dimensions, it has similar dimensions to some 1200L size single skin tanks and 300gl steel tanks, so makes for a good replacement in these locations.  Internal steel frame for strength and rigidity, but not in contact with the oil.Length 1.89m

Width 0.64m

Height 1.35m

SL1250BT1250 litre slimline Bunded Oil Tank DESO SL1250BTLike the bunded SL1000BT this tank also has compact dimensions and enough capacity to accept a 1000L fill without being too near to empty. However it is slightly taller than its little brother, but still, only 650mm wide (2’1″) for narrow access and installations.Length 2m

Width 0.66m

Height 1.66m

H2500BTDeso H2500BT ClosedThis is the most compact 2500L bunded tank available at the moment, square in shape for efficient storage and at 1.25m wide, it is similar in width to a 600gl steel tank and most single skin plastic 2500L tanks. Also, a galvanised steel frame adds to the strength for a long life span.Length 2.3m

Width 1.25m

Height 1.45m


Well done!  You’ve made it to the end of the article. Still not sure which tank is going to suit your needs? Please call us on 01722 714514 or use our contact form. We hope this helps!


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