"For Q2 M8" wrote in message
om...
"Roger Mills" wrote in message
...

Yet more info...
Operation "rip-up-the-floor-boards-n-have-a-butchers" complete

Found a valve under my hall (upstairs) floor boards.

I have a Honeywell V4073A1039
The V4073A is a motorised Mid-Position valve...
is it 3 port ? ie 1 input and 2 outputs ?

pipe goes from boiler to pump to valve (port AB):
port B seems to go to the airing cupboard (HW tank) and then back
(with feed to bathroom & back bedroom radiators ???)
port A seems to go to the other rads.

Anyway, the (5 core) cable from the valve goes into a small junction
box and then down do the main junction box in the kitchen (next to the
controller).

But the cabling and plumbing (radiators connected to the HW return
flow - HW tank to boiler ???) seems very different from the pdf I have
from the Honeywell site, didn't have much time - I'll check it again
tonight.

Can the V4073A give CH without hot water ?

Cheers,
Sam.

The short answer is YES, as long as it's installed properly.

It is now clear that you have got a Y-plan (more or less).

The V4073 is indeed a mid position 3-port valve capable of providing hot
water only, heating only, or both together.

For this to work properly, there *must* be a Hot Water OFF feed from your
programmer, and your cylinder stat must be the change-over type - with one
input and two outputs. One of these outputs is live when hot water is
required, and the other becomes live instead when the demand is satisfied.
[You'll see what I mean if you look at the Y-plan wiring diagram at
http://content.honeywell.com/uk/homes/systems.htm]

The reason I said it was "more or less" Y-plan is that a couple of radiators
seem to be doing something different!

It is not uncommon for the feed for the bathroom radiator to be taken off
*before* the mid-position valve - so that the rad will get hot whenever
either or both of the hot water and the heating are on. In this way, your
towells get aired in the summer when the water is being heated even when the
heating is off. Is this what you've got?

Roger