Roger Mills wrote:
I've just spent a few days in a holiday let in Cornwall, where the heating
and hot water was provided by an elderly-ish boiler which was unfamiliar to
me. Since one of the days was wet, and there was little point in going out,
I decided to investigate and take a few pictures - as one does(!)

The boiler was installed under a kitchen work-top, and was about the same
size as a dishwasher. On the front it said "Worcester Heatslave 2+", and the
model number shown on the rating plate inside was 30/42B - as can be seen
from:
http://www.mills37.plus.com/boiler_front.JPG and
http://www.mills37.plus.com/boiler_plate.JPG

Inside - in addition to the heat exchanger, gas valve, etc. - was a lagged
hot water tank, a pump and (according to the circuit diagram) a motorised
valve - although I couldn't see that, so it was probably behind the control
panel (which I didn't think I'd better dismantle!). The inside looks like:
http://www.mills37.plus.com/boiler_inside.JPG

A Google search on the GC# shown on the rating plate led to a record in the
Sedbuk database, as follows:
"001112,000005,Thorn EMI Heating,Thorn EMI
Heating,Marathon,30/42b,4178945,,1983,1,1,1,1,1,2,1,8.8,12.3,,,65,3,,0 ,2,1,20,0,0,,0,0,,,,,,,,2000/Feb/28
09:58"

I don't know what the column headings are, but Thorn EMI is presumably the
manufacturer, 30/42B the model, and 1983 the year of manufacture (there is
other evidence that that's when the flat was built - so seems reasonable).
On the back of the door there was a manufacturer's contact number starting
with 0905 (Worcester, before the '1' was later inserted).

I presume that Thorn EMI were using the 'Worcester' brand in the 1980's. Is
there any connection between this and Worcester-Bosch?

I'm not sure whether or not the boiler is a combi - anyone care to hazard a
guess? The primary side is vented, with a small F&E tank in a cupboard. I
could find no header tank for the DHW - which appeared to come out of the
taps at mains pressure. There was also no hot cylinder external to the
boiler - but I guess that the internal tank held several gallons. If you
turned the boiler stat up to High, you could get a reasonable bath fairly
quickly before the water ran cold.

Are there any boiler archaeologists out there who can shed any light on this
beast?
The internal picture shown several similarities with my Thorn M44/54.
I've owned it since 1982 and it was in the house prior to the conversion
to natural gas in the Southampton area when ever that was.
It is still going strong and is a doddle to maintain and spares still
available. I aslo have aspare one in the garage that I've not needed to
canibalise yet.

Bob