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
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.
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.
This newsgroup posting comes to you directly from...
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?
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!
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.
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
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.
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.
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).
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
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