We have 3 zone system with a taco zvc404 activating zone valves in the basement. Each zone (floor) has its own thermostat. The second floor loops are laid out in a way that loops are isolated in rooms, so if we added a power head control on the 2nd floor manifold we would be able to control the rooms as separate zones. My question is, how can we add 2 thermostats and power heads on the second floor to control these zones, and still get these thermostats to work with the taco zone controller in the basement? The zone controllers I see have a pump control output, but this is higher voltage. I've seen a tekmar 325 control that has a tn4 thermostat output - would this output allow me to connect to the basement zone control as a thermostat to activate the pump and basement zone valve?

I f you are trying to shut off or eliminate over shoot in these 2 rooms you could just wire the stats to the heads and a transformer. they will not initiate a call for heat. IF you need them to all for heat on their own then you will need to remove the zone valve for the floor and install tellestats for each room. The tellestats can be wired in parallel to the 404 in place of a zone stat. The problem will be that you will have very small zones calling for heat and short cycling the boiler. What do you have for a boiler?