RE: X10 control of CH and HW - Y plan confusion reigns...

["Jon Whiten" <jon@xxxxxxxxxxxx>]

Would replacing the Room and Hot Water thermostats with relays (controlled
by your HA system) and then leave both HW and CH on 24 hours sort the
control.  Then using a temp sensor in place of the HW and CH thermostats
and
have the HA software sort the logic.


Regards

Jon Whiten
http://www.whiten.co.uk


Regards

Jon Whiten
http://www.whiten.co.uk
-----Original Message-----
From: LeeUKHA [mailto:mailinglists@xxxxxxx]
Sent: Sunday, October 10, 2004 6:54 PM
To: ukha_d@xxxxxxx
Subject: [ukha_d] X10 control of CH and HW - Y plan confusion reigns...


A while back when I bought my current home, I replaced the (rather
knackered) CH/HW timer with a new digital one. At the time I never really
understood the wiring, but it's been working fine for a couple of years so
I
guess it was OK.

However, now I'm attempting to control the CH and HW from the HA server...

After some googling I appear to have a standard Honeywell Y-plan set up
(?).
I can get the CH to fire by shorting out two links (live into CH request?)
on the timers backplate, which I'm guessing I can simulate by having an X10
appliance module feed 240V into that connection. But the HW I have a
problem
with, there appear to be two HW connections, one for "HW request"
and
another for "no HW request". I not sure I understand why this is,
but
shorting 240V in the MW request does not fire the boiler, when I thought it
ought to...

What am I missing here? Can this system be automated with two appliance
modules? Will the current leak that keeps power indicators lit (like on my
elecy blanket) cause problems? Why didn't I just put cat5 to the boiler?

Any suggestion gratefully accepted...
Lee