RE: Heating relays and CAT5 power

["Nigel Giddings" <nigel@xxxxxxxxxxxxxx>]

Simon,

It would seem that the 1N4001 diode suits most applications (DC!)

Some interesting background here

http://www.jaycar.com.au/images_uploaded/relaydrv.pdf

Nigel

-----Original Message-----
From: Simon McCaughey [mailto:simonmcc@xxxxxxx]
Sent: 28 October 2006 10:10
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Heating relays and CAT5 power

Nigel,

That is excellent to hear! Your tidy solution certainly gives me
something
to aim for!

I suspected my ratings were ok, good to have that confirmed too.

What size of diode should be used?

S.

On 27/10/06, Nigel Giddings <nigel@xxxxxxx
<mailto:nigel%40corbenic.co.uk>
> wrote:
>
> Simon,
>
> I have built a VIOM based CH controller and used the matching relay
> boards which are rated at 1 amp d.c. at 24 Volts d.c. /110 Volts a.c.
>
> http://photos.corbenic.co.uk/dcp02093jpg.html
<http://photos.corbenic.co.uk/dcp02093jpg.html>
>
> I suppose it really depends what you will actually be switching, that
is
> to say what is it connected to in your heating system. My system
> controls wax filled zone valves, these then operate a switch to
operate
> the pump...
>
> A 3A relay should have no problems at all, you will probably find that
> your spur unit feeding mains power to the existing controls is only a
3A
> anyway...
>
> Running your proposed relays over CAT5 should be no problem but make
> sure you fit diodes across the coils to prevent back EMF caused when
the
> relays magnetic field collapses when de-energised...
>
> HTH
>
> Nigel

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