Help wiring HAI thermstat to elk expander


Active Member
I'm looking at the direction for the elk serial, etc expander and in the diagram that shows the wiring for hai, it seems to show them in parallel off one wire running from the expander.

Is this required or can i send 2 wires off the expander similar to the 485 bus on the elk? Basically my elk is located in between the two and would like two direct runs just for ease (i already have the wires that way)

thx in advance
The HAI Thermostat bus is a 300 baud so of RS-232 type bus that allows for multiple devices, up to 4. Since it is a non terminated bus, you should be OK running two runs.

Follow the directions in the M1XSP for proper operation!

Have Fun!
Hi Spanky -
Do you think that would be the case for 4 T-stats? I have the same situation but have 4 stats all home run back to the panel.


Beerguy (like the name),
I know customers have run 4 thermostats on HAI, but do not know how they are run. You should be OK, but you will have to try it. Maybe someone can chime in that has run multiple HAI thermostats.

The RCS and Aprilaire thermostats use RS485 with up to 16 thermostats and should be wired in a series configuration. If you have CAT5 running to each thermostat you can run the data lines to the thermostat and return the data, then go to the next thermostat data lines, etc...