"The oil tank is too small and it could therefore leak" - logic?

[NY]

We're selling our house and one of the questions our buyer's solicitor has asked us to get a heating engineer to comment on is that the buyer's surveyor said "the oil tank is too small and it could therefore leak". Those are the precise words as presented to us. How do you define when a tank is "too small", other than by the frequency with which you need to get it refilled. Why is a smaller tank "therefore" more likely to leak?

Is there something very obvious that I am missing, or have they lost the plot?

For the record, it's a 1400 litre bunded tank which needs to be filled about once a year, so the tank is plenty big enough for purpose and does not need to be refilled every few weeks or anything like that. And even if it did, that would not make it more likely to leak.

[GB]

Simple answer is that your buyer needs to get their own heating engineer to comment on that.

[Andy Burns]

Tell them they're welcome to arrange any inspection they like at their own expense, or walk away ...

[Brian Gaff]

Sounds like rubbish to me. Maybe they mean it needs filling more often and the wear and tear on the filler will thus wear it out faster. After all if they were unhappy about its mountings then they should say so. a bigger tank will need more substantial mountings in any case and I'd have thought be more likely to leak due to stresses and when it did, there would be more oil to clear up too. Brian

[Huge]

That isn't even a question.

And the response is [shrug].

Quite.

[Martin Brown]

How old is it? I can't see any reason why a small tank should be more likely to leak. It might spray fuel out of the vent if it is filled too quickly by a powerful tanker and brutal operator but that isn't leaking.

FWIW my oil tank is only slightly larger than yours. Its predecessor did leak but that was because it was mild steel, old and with water in the bottom rotting it from the inside. It was held together by Hammerite!

Are there any signs of damage to it or incorrect foundations?

[NY]

No signs of damage. The tank (bunded double-skinned steel) is about 4 years old, replacing a single-skinned tank that was very close to rusting through. It is resting on the same breezeblock piers as the previous one, which seem sturdy enough. The supply, sizing and installation was done by a certified heating installation company. But the question is (or appears to be) about the size of the tank and the likelihood that the smaller it is, the more likely it is to leak. That is the question I will ask our engineer to comment on when he comes to service the boiler.

Cloud cuckoo land!

[GB]

The question might arise through a misinterpretation of the surveyor's report. Or there could be a misprint, or just a standard butt-protection phrase in there about tanks leaking. There's nothing at all that you can do about it. If you ask your engineer and he says this is nonsense, that's not going to help your buyers when you tell them.

The correct response is that the buyers need to sort out with their surveyor exactly what he means, and then get their own advice, as they can't rely on yours. They are welcome to inspect the tank. Plus tell them all the stuff in the first paragraph above that I have quoted.

[Cynic]

With a typical 900 litre delivery and once a year refill there's no reason to consider the tank is too small. As a retired oil boiler installer and service professional I'd consider the report to be the creation of an pianist.

[Gareth]

My guess is that one of the paper pushing parasites involved in the house purchase process added the word "therefore" thinking more words and longer sentences makes him/her look clever. Without the word "therefore" the sentence makes sense as the tank *could* leak at some time in the future (though probably not for a few decades).

[alan_m]

Apart from the bit that says metal tanks rust.

Keep it simple by saying that it is an approved tank installed by a certified company around 4 years ago.

[charles]

I once* had an altercation with an advertiser in Radio Times who wanted to say "Because there is a 10 watt amplifier, there is no disptortion".

• in the days when BBC Engineering had some influence.

[Steve Walker]

I wonder if there has been a miscommunication - could they be questioning the size of the bund rather than the tank?

SteveW

[NY]

I've always wondered why people talk about the size of the bund. As long as it is as high as the inner part of the tank, no oil can leak out of the bund because the oil level in the bund will never go higher than the level in the inner tank, no matter how thick or thin the gap between the inner and outer skins.

[Rob Morley]

Does he perhaps think that the bunding is insufficient to contain the whole contents of the tank?

[NY]

Why should it have to? If the inner skin perforates or rusts, the inner tank will not vent all its contents into the bund, just a little bit which will fill up the bund to the same (lower than before) level of the inner tank. The oil isn't magically going to defy gravity and flow from a lower level within the inner tank upwards to overflow the top of the bund. Or is it really intended that a 1400 litre tank will be surrounded by a 1400 litre bund?

[Rob Morley]

Because if the bottom of the tank is raised off the ground and the bottom of the bund is level with the ground the bunding doesn't need to be as high as the tank?

[NY]

Our tank is an outer metal skin, totally enclosed on all sides, raised off the ground. Within that is an inner metal skin, presumably resting on spacers that keep it away from the bottom of the outer skin, and it is the inner skin that normally contains the oil.

The volume of the void between inner and outer skins (the bund) does not need to be anywhere near as large as that of the inner skin. Some people make it sound as if it does.

[Michael Chare]

You could ask for a copy of the report, or at least that part of it.

A full small tank has less oil to leak than a full large tank.

[Tim Streater]

It's complete nonsense.