Here's a question about sub-zoning from a manifold using electric actuators such as the Caleffi thermostatically controlled valve actuator( Link).

Let's say that our Zone in question has two circuits, and that the actuators replace the balancing valves on the manifold, such that the flow into each circuit is controlled by the actuator opening and closing. If the actuators are thermostatically controlled, is the Zone pump activated at the same time as the electric actuators? If so, how? If the zone pump is not activated at the same time as the actuator, then how does it become activated?

Thanks in advance for the insight!!

Typically, the actuator will have four wire leads from them. Two for 24V power , and two end switch wires. When the actuator fully opens, the end switch leads activate another relay then turns on the circulator pump.
Some controls (such as Tekmar) do this internally, and you only need to power the actuator, and end switch wires are not used.

Actuators do not replace balancing valves, by they way: they are open or closed, only.

If both are open, both still need to get the flow that they need. This is the function that balancing valves serve. Actuators simply allow zones that are not calling to stop getting flow.

If you only have two loops, and they are near the same size and require the same flow, then you don't need balancing valves.

Ahhh yes, I see that I was confusing the manual shutoff valves (on the return side of the manifold) with the balancing valves (on the supply side of the manifold). The actuators are replacing the manual shutoff valves (on the return side) so that the balancing valves remain in place for each circuit (on the supply side).

Thanks!!

The more I read about these actuators (from Caleffi) the more it looks like they are their own thermostat and you adjust their temperature sensitivity by turning the head of the actuator. Does anyone know if there are any actuators out there that have inputs for an external thermostat?

What I'm curious about is whether I can place a series of small rooms into one zone, have each room be its own circuit and then have a thermostat in each room with an actuator controlling the flow for that circuit.

That way I can get the whole zone balanced and adjusted to "normal", and if for some reason additional heat is needed in one room only, then the actuator for that circuit/room opens, without pumping heat to the entire zone.

Never mind the last question. Per Singh's suggestion, I've looked at the Tekmar products and see that I can interface thermostats to 2-wire actuators using the Tekmar Zone Manager (eg. Zone Manager 335).

However, I don't need the networking aspect of the tekmar zone manager so if anyone knows of a less expensive box which would allow interfacing of the thermostats to the actuators and a relay for the pump, all without the networking component, then please pass that along.

any thermostat can close a circuit with an actuator. it's all low voltage.

however it's common to use relays or specific zone relays which simplify wiring, give LEDs so you know what zones are calling, and provide the line voltage relay to a system pump in one box. These are pretty widely available from many manufacturers. We use taco ZVC relays, but there are many others.

the 335 is specifically for teknet 4 systems.