Linking roof vent switching to fans

[tonkski]

I have a conservatory with electrically operated roof vents and electric ceiling fans. I would like the fans to operate automatically when the roof vents are open. Power is supplied to the vents only for

30 seconds during opening or closing.

Using a couple of relays I could build a circuit that latches on when the vents are opening, and unlatches when they are closing, but I'm not confident I could design and build something safe and robust to switch 240v . Unless there's something off the shelf that would do the job?

Alternatively I could install a push-to-break switch at the vent, would something like RS part number 456-4615 be appropriate?

Any other ideas?

Thanks

Tonkski

[Lurch]

On 8 May 2007 12:46:50 -0700, tonkski mused:

I can think of a few ways but this bit stopped me actualy bothering to list any.

Leave it, just get someone else to do it.

[Phil B]

That switch looks simpler than a latched relay solution, unless you can somehow hook into one of the limit switch on the vent. No doubt you'd also get the cover for it - can you mount it out of rain? Phil

[Jethro]

Presumably though, you'd still use a relay and a low-voltage/isolated "signal" current for the switch, as a safety precaution in case of water contamination ?

[Jethro]

Maybe an optical solution ? I'm sure you can get a sensor which will switch a relay when darkened.

[tonkski]

I like the sound of that. Can anyone suggest an appropriate step-down transformer please?

[Jethro]

Maybe a doorbell one ?