"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Set Square wrote:

In an earlier contribution to this discussion,
ARWadsworth wrote:


http://tinyurl.com/b5wtw

says that that programmer should be of the type where heating cannot
be selected without hot water.

If I am following you correctly then I presume you are suggesting a
HW off connection from the programmer to terminal 5 to give seperate
controls.

Yes. There may be occasions - maybe when returning home from holiday
to a cold house, for instance - when you might want the heating on
without waiting for the hot water to heat up first.

Unfortunately, I can't get the pdf file, which you cite above, to
load - so I can't see what the rationale is for not having a CH-only
mode.

I've now managed to get the pdf file to load.

It comes pretty close to contradicting itself - referring to independent
control of HW and CH in some places and then saying that the programmer
must
not allow heating to be selected without hot water.

Pretty close to contradicting itself is generous, I thought it was a direct
hit on the Heating Only Requirement section.


I can't see that it matters *what* the programmer does in this respect -
the
effect will be the same. Even with no HW feed from the programmer, the HW
will still be heated (and CH not heated) until the cyl stat is satisfied.
So
if you want CH only, you have to turn the cyl stat down below the
temperature of the water in the cylinder.

I agree. So the only reason would be so the user can see a neon/led in the
programmer to say the water is on. There is no other reason


My suggestion of a HW-off feed from the programmer would enable the same
thing to be achieved without needing to frig about with the cyl stat.


Your suggestion would work fine IMHO. I might try it out as I have to fit an
electrical supply for an immersion on a W plan over Xmas (they need a back
up in the event of a boiler failure).

Adam