Richard Marx wrote:

Since the engineer's visit, the boiler itself has been making 'swooshing'
sounds every few seconds. It sounds like when you glide your hand through a
bath to mix the water. I suspect this is air, however the rads don't appear
to need any further bleeding as I get water straight away.

Yup that sounds like air...

The engineer did release air from one of the pipes above the boiler (flow or
return?) however the problem is still present. He also mentioned the bit at
the top of the boiler where the vessel is shouldn't have been fitted tilted
at 30-degrees, which it has. There is no room for it to lie flat.

Can't quite visualise what you mean here...

Any ideas?

The air may clear itself in a couple of days - it will slowly get
deposited into a radiator

PS: Should the boiler run constantly - not the gas flame, but the water
running through it, even when the rads and wall thermostat are off? What is
it circulating if there is no demand for heat or hot water?

Most boilers will certainly run the pump for a little time after they
have finished heating. Some may even be wired to run it continously.

--
Cheers,

John.

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