"Andy Hall" wrote in message
...
On Sun, 14 Dec 2003 16:15:04 -0000, "IMM" wrote:


"Steven Briggs" wrote in
message
news
In message , Andy Hall
writes

[snip praise of technology way beyond the comprehension of most
Plumbers!]

Andy, I didn't realise your MAN Micromat boiler was so clever.
If only the UK industry would drag itself into the 21 century with some
decent control technology. The cost of implementation is next to FA, a
mid-range PIC or similar could do the job for a few quid. Even I could
knock something together in a week or so's work, and I only dabble with
PIC's and software occasionally.

Very few condensing boiler now do not have load compensation control, at
modulates the burner. The problems is that when you want full output at
all
times, as when heating a thermals tore or quick recovery cylinder, most
can't do it. Some boilers do have terminals that when switched the
modulation is turned on or off. Some boilers, the Baxi is one and see
current thread on this, can either be full power or modulate, by only be
removing 3 jumpers from the control board.

All of which is very disappointing. If the boiler is going to have
a board of electronics with a microprocessor to read the temperatures
and control the modulation, then with virtually zero extra cost it
could directly monitor the cylinder temperature or cylinder stat and
operate the motorised valve. Given that, the boiler could be wound
up to full power for the hot water/thermal store cycle and back down
to modulating for the heating circuit when this is complete.

That is the idea. Some boilers have this function, but only a few.

All of this can be accomplished with
the controls available today, and simple
ones at that. In an existing property, there is almost certainly
wiring that will handle it all as well.

One way of fooling the boiler to ramp up to full power, is to parallel up
two wires from the return pipe thermostat temp sensor at the terminals at
the board. Find out what temps = what resistance. Then switch over to
either full resistance or none, whichever tells the board that the return
temp is cool when it isn't. Then the boiler us full on, and should not
interfere with the control logic of the safety circuitry. But the makers
would probably not like this.



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