Hello

I wonder if anyone could answer a central heating question for me.

I have an oil fired boiler fitted with a Riello RD3 burner - that's the
later one with the black control box and air inlet on top.

I came downstairs the other day to a stink of kerosene and checking
outside black smoke pouring from the chimney. I went through the list
of probable causes in the boiler manual troubleshooting section, first
replacing the nozzle which made no difference, then replacing the pump
which fixed the problem.

The problem that I have is that I checked the delivery pressure of the
old pump before I removed it from the burner and it was rock steady at
7.3 bar as per the manual.

I stripped down the pump that I'd removed from the burner. There was
no
damage or wear that I could see. The only thing that I noticed was a
thin brown coloured deposit coating all the surfaces within the pump
but
not blocking any ports or anything like that. It was easily removed by
washing all the bits and pieces in clean kerosene.

So my question is could the pump show the correct delivery pressure on
the gauge yet deliver the wrong pressure at the nozzle or do I have
some
other intermittent fault that's likely to rear its ugly head again in
the future?

Many thanks

--
Robert