Question regarding wiring a timer relay module (ALST-8)

[Paranoia Man]

Hello all,

 

Winter is coming, and when flowering I'm happy to leave the fan on low, this year I've only got little seedlings poking their heads out so no way do I need continual air exchange. I intend to use a couple of timer relays to turn on the fan for a few minutes every few hours (plus a thermostat to do the same if heat builds up in the meantime). I have what I hope should be a simple question regarding wiring one component in the chain that I hope a sparky can quickly confirm.

 

I'll be using the call for heating on the thermostat to power an H3D-M timer relay that outputs open-closed to a single fixed timespan (eg. one hour open, one hour closed, and so on). Because I want a shorter 'on' period for the fan, I bought an ALST-8 staircase timer to change the long H3D-M closed period into a shorter period of a minute or more. The diagram for this device is below:

 

 

I believe that terminal (3) is the live output when the relay is closed. I believe that I can wire that (along with a neutral) to the next relay (an SMC-2520-240) that will finally drive the fan. I have no idea what terminal (4) does, and suspect I don't need it for my simple case. I expect that I can use the staircase timer configured to screwdriver setting '3' (left-hand side diagram), although if I'm only using terminal (3) it doesn't matter.

 

My question is: am I correct in my assumptions above?

 

Big thanks in advance for any help, I really do appreciate you taking the time to help keep me safe. If anyone would like to see the finished setup, I'll be happy to post back here when I'm done (assuming I can work out how to upload images -- it seems to have changed again ).