Project, fans on a timer, never used relays

Hey guys, i know this forum is for cars, but, i have a dilemma, this is the project at hand, I need to turn on some fans. Now the story, The fans are going to be on a timer operating at 12v, and the fans will be on a set schedule. What i need to do is the following, when the Humidity sensor engages due to low humidity, i need a signal sent to the FAN assembly to turn on. BUT, i cant power the fans when the timer is in the off mode. So, what i was going to do was run a second power wire from the 12v and wire a second positive/negative to each fan. (BLUE WIRE IN IMAGE) So, here is why im here, I think i need a relay, I need a relay which feeds off the bottom wire (24v) and switches the 12v line (the blue wires) to turn on. I understand I'm using a 24v trigger to power the 12v fans, i want to add that i do have the means to turn that 24v to a 12v so if 24v is a problem then don't worry about it. I also, want to add a secondary Relay to send a signal to the TIMER line to not engage when the blue line has engaged. For that i searched the forums and found this. https://www.the12volt.com/installbay/forum_posts.asp?tid=102363 Will that work for my needs? ANY help is greatly appreciated.