Oil boiler vent fumes

[StrawberryTed]

I live rurally and the village is not in the gas grid. My neighbour has an (at least) 20 year old outdoor oil boiler located in a boiler house that vents about 30cm above the ground and about 30cm from the wooden boundary fence.

Every time the boiler fires up it absolutely reeks and is like having a massive articulated lorry exhaust pumping diesel fumes into my garden. It's worse when the wind is blowing in a certain direction but it seems the wind is mostly in that direction.

I've asked them to get it checked on numerous occasions and they get it serviced but it still smells so bad. Apparently it can't be fitted with a chimney to vent the fumes.

Anyone had this issue? I'm so worried about the damage it may be causing to my family's health 😞.

I have serviced boilers and some have what is called a "Balanced flue". These cannot be changed to a high chimney.
Can you put up a fairly high section of fence to stop the fumes getting easily into your garden?

It's their fence and it's quite gappy and low about 5 feet so yes it probably makes things worse.

Is such a boiler even legal? I would have thought a 20 year old boiler would need to be changed. It smokes occasionally too when the oil is running low. That is particularly bad.

Could a plume diverter be attached to the outside?
@NotTooOldPaul

@StrawberryTed These boilers are legal. All boilers need to be maintained and almost anyone can maintain an oil boiler (a gas boiler needs a gas safe person).
I'm not sure about a fume diverter. If it is a balanced flue.
Balanced flues work because appliance is sealed from the room in which it is installed and a twin-wall pipe vents directly outdoors. Air for combustion is drawn in through the outer pipe whilst the inner pipe removes the combustion gases to the exterior of your property.
It is possible that some sort of diverter could be fitted but it would need someone qualified to decide what is possible.
Can you put something solid on your side of the fence to make it fume proof? Even a sheet of plywood?

Thanks for the info.

I thought there would have been laws about emissions from these things. Crazy that they are allowed to vent at ground level which must be a danger to human health.
I also have an oil boiler which vents from the roof. It doesn't smell at all and is near my window.
Why would this one smell? Does that mean a seal is broken?

I guess I could attached a big sheet of plastic to the back of the fence to see if it helps