Relays - plea for help!

[Raymond <Reb.barnett@xxxxxxx>]

I've ordered three solid state relays and have spent the weekend playing
with trying to get them to operate the boiler. I'm having some
difficulties though, and I've got a hard deadline to get it working...
there are 2 days before the new kitchen is fitted, and access to the
boiler becomes possible but a lot more awkward. Any help would be
extremely appreciated!

The problem is as follows. With the SSR connected in series or in
parallel to the existing timer control, I can successfully switch the
hot water/ CH on. However, when I turn the SSR off, I get a high
frequency clicking from one of the relays buried inside the boiler, that
does not sound healthy. In the off state, a multimeter records zero
volts output from the SSR. With the SSR disconnected, the existing
control timer seems to hold the boiler input at approx. 60v, but this
seems to drop to zero if it's left off for long enough. If I disconnect
all inputs to the boiler (thus mimicking the zero volt input from the
SSR), the boiler remains off (as expected) and does not produce any
clicking.

My only guess is that the SSR never completely switches off, or pulses
voltage, but I'd of thought the multimeter would have spotted that.
Consequently I can think of two solutions: to wire a load (low wattage
lamp) in series with the output from from the SSR, to determine if it's
because the boiler represents too low a load to cause the SSR to switch
off (because nothing to sink current from the SSR?). Second solution is
to wire a relay either between the output of the SSR and the boiler, or
more logically bin the SSR and simply use a relay between Comfort and
the boiler.

Any comments, or preferably solutions?

p.s. I forgot to mention, I stuck a multimeter across the inputs to the
SSR when Comfort had it switched off, and it recorded 0v, so the SSR
*should* have been completely switched off.

Cheers,

Ray Barnett.

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