Heating Oil, 2000 L tank vs 1000 and water

[misterroy]

My near neighbour has a 5 year old 2000L oil tank. His pump to pressurise the kerosine failled two days ago. He spent today draining the water out of his 2000L tank. This is the second time he has had this failure mode, I forget how much water was in last time, but it was astounding. He had assumed it was rain getting in driven by the wind and took measures to mitigate. I have a 25 year old 1000L tank, never had any problem with water in the fuel. I am pretty slow at ordering fuel and have ran out a few times, and every last drop was burned from my tank. Last time I looked in my tank only about 1/5 th of the bottom was covered by liquid, and there was no sign of a water/kerosine border, luckily I got fuel before I ran out. Is it just the extra volume of air that is leading to my neighbours trouble? Both our tanks are in full sun.

[Tim Streater]

Our 2400 tank at the old house never gave this problem, and when we had the

1200 tank replaced here with a 2400 one, chummy who did the work and pumped the oil into a holding tank and said there was no sign of water or grot in the outgoing tank. So I'd guess your neighbour has a leak somewhere above the full-line which is letting water get in. 1000 is rather small, IMO. We ran out here once with the smaller tank as I misjudged how much was left. Also, with a larger tank you can afford to wait until the price is more suitable.

[misterroy]

How far south are you Tim? We are NW Scotland. thanks

[S Viemeister]

We're in northwest Scotland, too, on the Kyle of Tongue. We had our original 2000l tank replaced a few years ago with a 2500l one. There did not appear to be any water or crud accumulation in the old one, and the new one has been fine so far.

[Tim Streater]

Kent.

[Chris Hogg]

A previous residence was on a small estate of bungalows and occupied by me from new. We all had oil-fired central heating. The tanks were rectangular steel things. I forget the capacity, 1000 litres maybe. Many of my neighbours had to have their tanks replaced over the years because they rusted through from the inside. They all had vents in them covered with a mushroom shaped cap, with three 'legs' that screwed onto a stub of 2" threaded pipe. They were not screwed down very far, and there was quite a gap between the lower edge of the cap and the top of the threaded pipe, into which rain could get blown by strong wind. From the very early days, I screwed the cap on my tank as far down as it would go so that the lower edge of the mushroom was below the top of the stub of threaded pipe.

I never needed my tank replacing in the twenty years I lived there.

Has your neighbour got a tank vent cover that isn't screwed down as far as it could do, or something like it? I assume these days that all tanks are plastic of some sort, so rusting isn't a problem, but rain could still be blowing in around a poorly set vent cap.

[Martin Brown]

My ancient tank had a few mm of water inside at the bottom as it neared end of life at ~30 years but nothing like you describe. There must be a leak somewhere high up on the tank allowing water ingress. I suspect most of mine was accumulated from condensation dripping in when the air was warm and humid and the tank contents still very cold.

The exact conditions for this happened last week when the thaw came. For a few hours every metal surface in my garage was dripping wet through being much colder that the warm moist air that suddenly arrived!

There is a major defect on his tank presumably above the maximum fill level or he would have noticed kerosene running along the ground.

[Brian Gaff]

I was also wondering how the tank is mounted and if all the pipework has been checked. I know some people that have had tanks get small slits or holes due to them flexing with differing amounts of oil and the heave and slump of the underlying ground in different temperatures causing cracks in the mounting and allowing the tank to itself flex. Brian

[John J]

Oil boiler servicing should include checking for water accumulation in the bottom of the tank. Plus the tank should slope way from the draw off and have a drain/sample point at the lowest part. Not rocket science to a competent serviceman.

[Tim Streater]

The slope of the tank, or the existence or otherwise of a drain/sample point at the lower end is hardly in the gift of the serviceman now, is it.

Neither will it occur to most people that, if they are having a new tank installed, they should ask teh installer about such matters.

[chop]

Any competant installer should do that without being asked.

[John J]

Correct installation of an oil storage tank is subject to national standards. Anyone ignoring these has probably left his horse parked round the corner out of sight.

[misterroy]

A drain if needed would surely come pre fitted on the tank. Getting a fitter to add one could lead to all sorts of trouble. How wold they reach down to the inside bottom of a 1.8 M tank to add a nut?

[Martin Brown]

I don't think I have ever seen one with a secondary low point draw off for water. If it was ever necessary then the same sort of pump that is used for transferring fuel from an old tank into containers was used but with a rigid dip stick on the end to hit the lowest internally.

Mine has never had sufficient water accumulation to worry it, but towards the end of its life the thinning caused by corrosion at the surface of the water did for it. The whole thing was basically rust and Hammerite at the weakest point. The guy who installed the new tank said he thought it might last a few years more on initial inspection. However, when he tried to move it the base stayed put and the top tore away. Luckily by then there was almost no fuel at all left in it to spill.

Both tanks had sufficiently folded over vent pipes that there was no risk of water getting in that way. ISTR old one 2" ID and downwards facing after making a U-turn with a diameter ~ 8".

New one is a mushroom type vent and all plastic bunded tank.

[Michael Chare]

Well in Wales they are different from England. `

Was that what you meant? -:)

[Tim Lamb]

Parking a large metal tank in full Sun has caught out rather a lot of Farmers over the last few years. The advent of nice green diesel fuel (often referred to as FAME – Fatty Acid Methyl Ester fuels) along with their attendant Fungi,bacteria and yeasts, has shown how vulnerable such installations are to internal condensation.

My fuel tank is housed in a barn, out of the Sun and casual theft but rather inconvenient when it comes to filling a tractor.

[John J]

Oil tanks from mainstream suppliers come with a 1" BSP socket outlet fitted slightly above the bottom at one end and a 1/2" socket set flush with the bottom at the other end. It's normal practice to screw a drain plug into the 1/2" or alternatively connect a gate valve using a steel nipple and to avoid scrotes playing about to empty your tank a blanking plug screwed into the gate valve. The other end is fitted with an outlet of one type or another. (See

) the tank is then set on a sloping stand so any water or sludge migrates to the drain valve. 1" is adequate but frequently installers get enthusiastic and 3 or 4 inches can be seen. The greater the slope the more oil remains in the tank when the boiler runs out of available fuel.

[Brian]

One obvious source is the oil supplier. Do you both always buy from the same supplier?

[Vir Campestris]

1000 is about a years use for us, so it's fine.

If I could persuade SWMBO to order more than 500 at a time it would help though!

Andy

[Vir Campestris]

AIUI it's UV that does for new plastic tanks, not the rust that killed metal ones.

Ours lives in its own little room in the dark. That also means it will be easier for thieves to go for someone else's oil!

Andy