How Can I Connect C to the The Argo ARM-4 Control Board

[NaserGalaxyNote]

We have a 4-zone Argo control unit (ARM-4P). The thermostats all connect to this device and it enables different zones - and the boiler - depending on which is calling for heat.

What I'm wondering is about swapping thermostats. We currently have 2-wire thermostats around the house, mostly connected via old 2-conductor wire. They run on batteries which are always seemingly dead or dying and we can't really use the scheduling features or any wi-fi controls. I also have frequent relay chattering which i think may be due to low power coming from the stats (they also have a relay in them). I'm going to run new 5-conductor thermostat wire to them and I'm wondering about the capabilities of this Argo control unit.

Each zone has 2 conductor terminals marked Tw & Tr. The thermostat wires connect to these terminals. In addition there are 2 other terminals in the Argo unit (1) 24VAC and (1) Common.

What I'm wondering is if i can use those terminals to provide power to my thermostats once i have the proper wire in place, and if so what's the right way to wire them? Do i effectively share the Common and 24VAC between all of the thermostats?

[CoolingWizard]

@NaserGalaxyNote ,

The ARM 4P is rather unique power set up.  It does operate on 24VAC power, however, it sends the 24AC Power out of the 4P on the W wire and not the R wire.  In order to connect a Nest Thermostat you need to wire the Thermostat R terminal to the 4P W terminal and wire the Thermostat W terminal to the 4P R terminal.  Next, connect the Thermostat Common terminal to the 4P COMMON in the upper right side of the board. 

The manufacturer recommends that an IR-822 relay isolation board be installed for smart thermostats.  If the 4P Relays are chattering it tends to mean that the power supply is not supplying enough power. The ARM 4P Uses only a 30Volt Amp class-2  transformer and it needs to be upgraded to 40VA. 

AC Cooling Wizard

[edemjack82]

Yes, you can share the 24VAC and Common between all the thermostats, just be sure to wire them properly to ensure each thermostat gets the correct power rigid klick. The 5-conductor wire will help with both power and communication to avoid issues like relay chattering.