How to interlock fan with ERV controls

[mzcarey]

I have a two-zone system with one communicating and one 24 volt thermostat, and I am running the UT-3000 off a separate transformer. I also have an ERV with its own controls, which are powered by a 24 volt transformer within the ERV. I want the furnace fan to run when the ERV is on. However, when I connect the output of the ERV control to the Dry Relay, it does not energize. The ERV control is simple, and appears not polarity sensitive...just hook the two terminals on the ERV to the two terminals on the control. I have tried hooking each of the ERV control terminals to the Dry Relay on the UT-3000. Do I need to do relay isolation here because the ERV is powered by its own transformer? That is, do I need to drive a separate relay with the ERV control, and hook the terminals of the relay to R and Dry R in Zone 1 on the UT-3000? Thanks!

[Paul Z.]

There must be a "G" signal for the relay to operate.