On Nov 11, 4:04*pm, Graeme wrote:
Hi,

We have the above oil fired boiler, and the lockout keeps operating. *It
was serviced mid October, and the guy who did it cleaned everything, and
replaced a jet, but could find no obvious fault.

It locked out 29th Oct., twice on 8th Nov. and four times (so far)
today. *Any idea what the problem might be, before I call the guy back?
I know nothing about boilers, and am not about to start pulling it
apart. *Cold up here, in NE Scotland :-)
--
Graeme

If it's locked out whilst firing as opposed to startup, (it's
important to discover which). This means the flame has gone out or
controller thinks it has.
The flame can go out through lack of fuel or air or contaminated fuel
(eg water).
It can lock out because it thinks the flame has failed though this may
not be so, ie the photocell is dirty or defective.
There is also an air pressure switch that indicates to the controller
that the fan is running, this can go faulty. Apart from these, there
could be loose connections which can be a bugger to find. It is a
fail safe device, if in doubt, it locks out.

If it is failing on startup there are a whole lot more possible
faults. You have to note the exact point on the startup sequence that
lockout occurs to know where to start looking.
Intermittant faults are a bugger on complex equipment even if you work
on it every day. It's hard to blame your engineer.