Re: Second Opinion Needed? Central Heating Automation on the cheeep..

["Jon Lawrence" <jon@xxxxxxx>]

In a way, I have a similar system.
Our boiler has an old style mechanical switch timer on it. This started to
play up. So I set the heating switch permanently on, and installed a relay
in the output line. The relay is switch by a dc supply controlled by a
AM12.
Works a treat.

Jon

----- Original Message -----
From: "Ian Lowe" <ian@xxxxxxx>
To: "UKHA Mailing List" <ukha_d@xxxxxxx>
Sent: Thursday, February 14, 2002 6:36 PM
Subject: [ukha_d] Second Opinion Needed? Central Heating Automation on the
cheeep..


>
> Okay,
> I am looking at my Central Heating, which I am fairly certain is about
as
> standard as standard can be (cheap builder) I already swapped the dumb
timer
> for a smart(ER) one, but the inflexibility of even this quite complex
> controller is just getting annoying..
>
> Given our current HA setup (see SWMBO thread ;) ) the prospect of
bringing
> the heating within the whole Web/TV Menu/Server setup is extremely
> appealing..
>
> Now, there seems to be a standard wallplate for all of these
controllers.
> You want to add a controller with more features, you click off the old
one,
> click in the new...
>
> the faceplate looks like a pattress box, with a row of pin contacts
across
> the top..
>
> the contacts are labelled:
>  N  L  1  2  3  4
>
> And the helpful wiring diagram shows that "L" is the live
feed, "N" is
> Neutral Return *for the timer only*, and the connectors have the
following
> behaviour..
>
> 1 is connected to live when the Hot Water is "off"
> 2 is connected to live when the Central Heating is "off"
> 1 is connected to live when the Hot Water is "on"
> 2 is connected to live when the Central Heating is "on"
>
> This seems to be a "cover everything" setup, as our own
system doesn't
make
> any use of the "off" connections...
>
> Basically, it looks like the entire function of the controller is to
act
as
> a timed relay, throwing two switches.. (the thermostat etc are all
wired
> into the ratsnest control box which actually works the motorised
valves
etc
> below this...)
>
> Now, the point:
>
> I have trivially automated this using two AM10's. :)
>
> Much prodding with my multimeter, with the system in it's various
states
> shows me that the Neutral return from the controller does, in fact,
only
> allow the timer to be powered, it serves no extra purpose. Also, the
"live"
> feed to this connector block is a true "live", not switched
about or
> processed in any way. (all the control is on the Neutral leg of the
> circuitry).
>
> This indicates to me that the entire Heating system can be viewed as a
Black
> box from this point.
>
> I have an AM10 for each system. Plugged into the AM10, is a short
lead,
> which has *only* the live wired, (the system is double insulated) and
the
> live *only* from this is connected to the wire which used to be
connected
to
> pins "3" and "4" respectively.
>
> This works nicely, and I'm rather pleased.
>
> I would just like to know, is anyone currently sitting hand across
mouth
> saying "you what? My God Man, rip it out before your house
catches fire!"?
>
> :)
>
> Ian.
>
>
>
> For more information: http://www.automatedhome.co.uk
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