On my own server, I had a tree farm feeding a boiler, and it worked just fine when offline. The whole base paused, then resumed when I was back online. I didn't add a chunk loader until later. Since this is a server with other people playing, definitely keep your base inside of one chunk. (always active machines, power and fuel sources.) That way, if someone walks by your base while you are out, everything will fire up and run properly, then pause again when the chunk gets unloaded.
Redstone conduits will semi-load other chunks that they run into. The conduits and machines will operate, but trees and plants will not grow. If your base spans multiple chunks, this can cause your boilers to fire up and run, but not have a way of refueling. Keeping all conduits, machines and fuel generation inside the same chunk will keep everything running when someone comes within range of your base and causes the chunk to load.