On Feb 2, 8:07*am, Piers Finlayson wrote:
My oil fired boiler has started whistling while running. *The
high-pitched whistle starts about 10s after fireing up, stays pretty
constant while running and then tapers off after the boiler
extinguishes itself.

Any suggestions as to what might be wrong? *I've seen various
suggestions around a build up of limescale, but they seem to normally
be referring to a much lower pitched rumbling sound.

Thanks,
Piers

1. Build up of crap on the fan or in the housing
2. Motor bearings failing
3. Problem developing in the oil pump
4. Oil starvation in the feed to the pump caused by clogged filter
element either at the tank, between the tank and the boiler or within
the pump itself
5. Firestop fuel valve almost closed

If it takes 10s after firing it does suggest a fuel starvation problem
as a vacuum builds up in the pump in this time