Just posting this solution so that it nay join the Great Google in te
sky as a serachable enity.

Symptoms. e.
Generally this means its coked up, and it was. But after cleaning it it
took a very long time to light, when I remembered it was the same last
time I decoked it...but this time after 24 hours had barely reached
150°C oven. Which exactly corresponds to an Aga with no high fuel rate
available (they toggle between low and high fuel flow controlled by a
thermostat).

The thermostat appeared to work - turning it below the temp gave a click
and voltage across its pins leapt to 13v AC...from zero...

So PSU worked, thermostat worked. It was starting to look like some
issue in the float chamber dildo thingy...so I looked online, and, Hey
Presto!, a man with an Aga explained that how the 'carburettor' works,
is that a bimetallic strip heated bt the thermostat controlled current
from the PSU, the thermostat is up to temperature, presses down on a
pin and that somehow blocks the high fuel flow valve. Its that simple,.
And that wax from the fuel cab build up there, but vigorous agitation of
the pin will often clear it.
Fortunately UK.D-I-Y has many examples of masturbation, so a vigorous
wank on the pin with a thumbnail was undertaken, and presumably it
spaffed its wax, because the temperature stated to climb and reached
correct operating temperature in under 3 hours.

Interestingly the Googling also revealed that the Aga is set up to run
4cc a min low fuel and 8cc a minute high, which gives an upper an a
lower bound for fuel consumption so at least 172 litres a month, and at
most 350 litres a month.
#
At current prices between £70 and £150 per month

It is also reckoned to dump 600W - mine is anyway as a two oven - the 4
ovens dump 900W - into the house.

So the 'cost' of that heat is about 16p a kWh to 32p a kWh. I reckon
about 22p average.








--
How fortunate for governments that the people they administer don't think.

Adolf Hitler