Manifold/TRV actuators - 24V or 240V?

[EccentricAnomaly]

I've picked up the Maplin 24VAC power supply - it seems to use 4-5W when nothing is connected (though my basic plug-in power meter always shows 1W so it could well be only 3W).

I'd be very suspicious of the reading of a basic power meter on a very small and probably very reactive load.  Does it give a power factor?

[Baz]

Yes, it will be the legislation that is slightly different depending on whether the psu is built in or not.
The on off switch is pointless but rememer it is an EU requirement so not based on common sense. This year my company will spend up to 500K on switches that will never be used except by the Chinese and Czech production line worker who has to check they work. Lots of bits of plastic and metal resources squandered, but we are complyig with the law while most of our counterparts in the EU probably are ignoring it.

[SimonHa]

...I've picked up the Maplin 24VAC power supply - it seems to use 4-5W when nothing is connected (though my basic plug-in power meter always shows 1W so it could well be only 3W). It has a dazzling (can't look into) blue LED on the front... how much might that be wasting?! (OK, so probably not much)...

Well, having been on 24x7 for a week the blue LED on the Maplin transformer seems to have gained an energy conscience and burnt itself out! The HobbyBoard is only switching 24V so the transformer's on all the time at the moment.