RE: Simple flow switch for HA feedback

["Brian Smith" <briview@xxxxxxxxxxxx>]

Fair enough.  I have no experience of Comfort so I've not idea on the
best
1-wire interface.  It's largely irrelevant if the input to Comfort isn't
there but why would you be looking for a temperature increase.  I thought
boilers were set to output at a set temperature and then were largely on or
off so wouldn't you just have a rule that says reading >60C (or what
ever) =
=3D
boiler on?  I'm not sure ambient temperature would really come into play
then.  Then the only issue would be how quickly the sensor cooled down
afte=
r
the boiler switched off.  Not sure on that but most boilers overrun the
pum=
p
for a few minutes anyway so it'd probably just be a case of setting the
temperature threshold closely enough.

Just a thought.

-----Original Message-----
From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Paul Gordon
Sent: 29 June 2007 16:47
To: UKHA Group
Subject: RE: [ukha_d] Simple flow switch for HA feedback

Yes, this was/is something I have also thought of, and may well do
anyway..=
.
Not sure it would be OK for real-time event processing though, depending on
the speed of response.. - i.e. How soon after the boiler has fired up would
the DS1820 signal this fact?? - due to the potential range of temperatures
that could be experienced in the environment, you'd have to configure a
fairly significant threshold before determining that the heating is
definitely on... Temps of 30C aren't unheard of in this country, so
anythin=
g
below that couldn't be relied upon as a definite. I would think that a
threshold temp of at least 40C would need to be set as the threshold. If
th=
e
ambient temperature is 20C, then you'd have to wait until a 20C increase
wa=
s
measured. Granted with the sensor clamped fairly tightly to the bare copper
pipe, I don't suppose this would take ages, but I still think there would
b=
e
a noticeable delay, which isn't good if you want to have comfort run a
response when the heating is switched on...

Also, I'm not currently aware of a way to interface a 1-wire temp sensor
directly to comfort... I imagine that it might be possible to modify an
LSM01 board to switch based on a temp input level rather than a light input
level (such a use is even alluded to in the LSM01 docs), but it seems the
LSM01 isn't actually available any more (it's disappeared from the CHC
website), and finally, I've had a hard enough time getting the LSM01 board
to work in its intended configuration, so I don't hold out much hope for my
ability to modify it...

I don't want any reliance on a PC for this function, the communication must
be directly between the heating system and Comfort.

Cheers.

Paul G.



-----Original Message-----
From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Brian Smith
Sent: 29 June 2007 16:19
To: UKHA Group
Subject: RE: [ukha_d] Simple flow switch for HA feedback

If it's monitoring you're after would a temperature sensor not be cheaper
and easier retrofit.  I was planning, but confess haven't got round to yet,
to put a 1-wire sensor on the output of the boiler to monitor when it was
actually firing.

-----Original Message-----
From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Paul Gordon
Sent: 29 June 2007 13:16
To: UKHA Group
Subject: RE: [ukha_d] Simple flow switch for HA feedback

Cool thanks. It's hopefully for feedback into Comfort of the Central
Heatin=
g
status. Hoping to fit one on the output from the boiler the feeds the CH
leg. I'll take a look at the suggestions.

Paul G.


-----Original Message-----
From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Tim Hawes
Sent: 29 June 2007 13:14
To: UKHA Group
Subject: Re: [ukha_d] Simple flow switch for HA feedback

Paul,

Not quite sure what you want it for (irrigation, central heating etc.)
but RS have a few (!) options.

257-076 @ =A311+vat, 15mm but not compression. max temp 85 degC
256-578 @ =A324+vat for 22mm compression. max temp 70 degC
256-562 as above but 15mm compression
395-6912 @ =A3102, 1/2" BSP, max temp 80 degC

HTH,

Tim.


On 6/29/07, Paul Gordon <paul@xxxxxxx> wrote:
> Can anyone point me in the direction of a simple flow switch that
could
> be plumbed in-line in 15mm pipe that could connect to a comfort input
> zone (i.e. volt-free contact)
>
>
>
> TIA