Date   : Mon, 28 Sep 2009 17:18:00 +0100
From   : robert@... (Rob)
Subject: RR09 Photos (Day 2)

On 28/09/2009, Jonathan Graham Harston <jgh@...> wrote:e
>
> Have you looked inside a central heating boiler nowadays? When I
> helped my dad put his in in 1975, central heating control was
> effectively three switches in serial controlling a gas valve:

> After a lot of nursing my boiler died last year and I hed it
> replaced. It's a veritable computer in there. The plumber had to
> take the PCB back to the supplier because a microcrack on the board
> kept causing it to crash on startup. (!)

And there's the rub.  Even a plumber could probably get the
three-switches-in-series sort of installation working again, even if
one has to bypass a switch temporarily. But the new ones, it's pull
the board and leave you without heating or hot water until the
supplier sends a new one ..

We recently had ours replaced, too.  The old one had a large box
marked "Wiring centre" into which everything connected.  It was little
more than a lot of terminal blocks connected together on a PCB so as
to connect up the various switches to the gas valves, water valves and
pump in the right way.  Quite understandable..   The new boiler has
everything built in - single "heating on" connection fed from a
combined timer-thermostat, and a large PCB that is effectively just
one big black box.  And I'm still not sure it's working right..