Ports to connect on The Attendant: BUS1 – BUS4 or Heater H1 – H5
Ports to connect on The Attendant Mini: BUS1 – BUS2 or Heater H1 – H2
These devices should only be powered directly from the power center or breaker panel. Do not run electricity through a relay as The Attendant will control the device to turn on/off by using the communication cable.
Serial RS-485 Connection (BUS1 – BUS4)
While almost all heaters are able to be controlled via the low voltage dry contacts labeled H1 to H5 or via high voltage relays, many more recently manufactured heaters are capable of being controlled via serial RS-485 communication. One of the main benefits of using RS-485 to control a heater is the additional information that can be obtained from the heater itself in the form of error or operational codes.
When configuring the heater in The Attendant mobile app, ensure you choose the appropriate make/model and a control port of Serial with the port you connected the heater to.
Low Voltage Dry Contacts (H1 – H5)
The Attendant provides five low voltage dry contacts in the base unit that can be used to control one or more heaters (gas or electric), heat pumps or even low voltage lighting. The manuals provided with most heater/chiller devices will typically provide the specific wiring instructions for connecting to an external control center, in this case The Attendant.
You will need to reference the heater’s installation manual in order to get specific details about how to connect it to The Attendant for remote control.
In all cases when using a low voltage dry contact connection:
- Wire the heater to a power source as per the instructions in the heaters manual.
- Please note: The Attendant does NOT control power going to the heater.
- The Attendant should be treated as a regular thermostat/aquastat with simple dry contact call for heat/cool operation.
- Use the appropriate temperature-rated wire; refer to the hardware manual or manufacturer’s recommendations. If no guidance is provided, you should use wire that is rated for 105°C.
- The heater’s power should be switched to ON when in normal operating mode.
- Set the thermostat on the heater to it’s maximum setting.
The following is a typical example of how heaters are wired at the heater:
