I have a 70,000 BTU boiler with currently 3 of 4 zones used.
2 are for heat and 1 is for the hot water coil (the priority zone)

I recently added 2 more zones from an addition I have done. They have kickspace heaters and the FL100 in the floor heaters from Smith Environmental. (I describe them as a radiator in the floor with a blower)

I have done all the plumbing to the boiler but not the hook up yet. I keep looking at the zone controller and wondering how to update it to add more zones.

Any advice on changing it and what I may be getting into is very appreciated.

Mike

Combine both the new zones into onethermostat and one valve for both. This will give you the maximum you can control with your setup you have now.

Option B is that you get a larger zone control and wire/valve/thermostat each separate.

I want to add zones. That's why I ran it that way, or I would have saved $200 running one set of pipes instead of 2 LOL

Just don't know what I'm getting into with the zone box. I would prefer some advice/tips ahead of time if its possble

You are really getting into nothing but low voltage wiring. A zone control come with a wiring diagram and if you can follow one of those your good to go. Just get a control that will service all your zones you have now or get the next size up if you plan on another addition.

I would use the remaining spot on your existing zone control and then purchase a single zone control (the same brand as the existing one) for the last zone. Tie the "T" contacts from one control to the other so the boiler will turn on. Controllers are much more service friendly than a rat's nest of wire at 3 AM.